Mission
The Novel Brachytherapy Technology Group at EngerLab develops advanced treatment planning systems, novel radiation sources, and delivery methods to enhance the precision and effectiveness of brachytherapy. Using Monte Carlo simulations, novel radiation sources, intensity-modulated delivery technologies, and AI-assisted algorithms, we design treatments that conform radiation dose more closely to the tumour while protecting surrounding healthy tissue. Our goal is to increase tumour control, reduce side effects, and improve quality of life for patients receiving brachytherapy and related treatments such as intravascular brachytherapy.
Members
Projects
Intensity Modulated Brachytherapy
Alana Thibodeau-Antonacci, Ph.D. Student, Maude Robitaille, Ph.D. Student, Jonathan Kalinowski, Ph.D. Student
The critical limitation with brachytherapy is the rotationally symmetric dose distribution provided by brachytherapy sources, delivering high dose to the tumor but often with poor tumor conformity due to the non-symmetrical shape of the tumors resulting in dose spillage to surrounding healthy tissues.
For example, large and irregular gynecological tumors, which extend into the parametrial and/or paravaginal tissues cannot be treated with curative intend by using intracavitary brachytherapy implants alone without overdosing nearby healthy organs causing side effects but must be supplemented with invasive interstitial high dose rate brachytherapy to enable conformal dose delivery to the tumor while reducing dose to healthy tissues. However, despite the excellent clinical results, this treatment is not available to all patients due to its invasive nature, lack of resources and trained radiation oncologists. For prostate cancer, disease-free survival is higher in patients treated with high dose rate brachytherapy combined with external beam radiotherapy compared to those treated with external beam radiotherapy alone.
Our group is developing the next generation of high dose rate brachytherapy technology, including prototype delivery systems for intensity modulated brachytherapy treatment of prostate, cervix, vaginal and rectal cancers. These systems will enable anisotropic intensity modulation of brachytherapy dose distributions by incorporating rotating metallic shields inside brachytherapy catheters and applicators.
Designed and delivered with accurate anatomic reference, the developed systems will tailor treatments to each individual patient by treating all parts of the tumor without needlessly irradiating large regions of normal tissues surrounding the tumor. Intensity modulated brachytherapy will increase the probability of response and cure while avoiding toxicity, which will increase the quality of life of patients suffering from cancer.
Monte Carlo-based Dosimetry
Jonathan Kalinowski, Ph.D. Student
Monte Carlo method is gold standard in simulation of radiation interaction with matter and is widely used in medical imaging and radiation physics. It plays a key role in medical physics research and development of novel technology for imaging and therapy equipment. Our group develops Monte Carlo based radiation dose calculation engines and treatment planning systems for use in conventional and intensity modulated brachytherapy, as well external beam radiotherapy.
For brachytherapy applications we have developed a Monte Carlo based radiation transport package called RapidBrachyMC, coupled to dose optimization algorithms, contouring tools and a comprehensive analysis package. This toolkit is standalone and enables planning of an optimal and accurate radiation dose to the tumour while sparing healthy tissues. The complete treatment planning system is called RapidBrachyMCTPS. It can be used to validate dose distributions from clinical treatment planning systems or commercial model-based dose calculation algorithms and is also well suited to develop and validate novel combinations of radiation sources and applicators, especially those shielded with high-Z materials.
Characterizing the Axxent® Electronic Brachytherapy Source X-ray Spectrum and Its Dosimetry
Azin Esmaelbeigi, Ph.D. Student
In addition to sealed photon emitting radionuclides, electronic x-ray systems can also be used to deliver high dose rate brachytherapy. At the Jewish General Hospital, we use the Axxent® electronic brachytherapy system (Xoft Inc., Fremont, California) to treat rectal cancer. This system uses a miniature electronic x-ray source (50 kVp) contained within a flexible probe to generate low energy x-rays. Azin is characterizing the Axxent® electronic brachytherapy source x-ray spectrum and its dosimetry through x-ray spectrometery, Monte Carlo simulations as well as measurements with ion chambers, scintillator based detectors and radiochromic films.
Treatment Plan Optimization in High Dose Rate Brachytherapy
Hossein Jafarzadeh, Ph.D. Student
Catheter Position Optimization in High Dose Rate Brachytherapy
In interstitial high dose rate brachytherapy, a highly radioactive source, usually 192Ir, is temporarily placed inside or in proximity of the tumor via thin hollow implanted catheters which are connected a machine called an afterloader. The afterloader contains a single radioactive source at the end of a wire. The source is pushed into each of the catheters, one by one under computer control and guided to the tumor site. The computer controls where along the catheter the source should pause to deliver its radiation (dwell positions) and how long it dwells at each position (dwell time). After the desired dose is delivered, the source is pulled back to the afterloader and the catheters are removed. Since the dwell times are optimized, the position of catheters has a major impact on the treatment plan quality. Efforts in optimizing the catheter positions have not been explored as extensively as the other aspects of the treatment planning workflow. This gap in knowledge motivates us to further explore this problem.
Penalty Weight Optimization in High Dose Rate Brachytherapy
Treatment plan optimization problem in high dose rate brachytherapy is formulated as a constrained optimization problem. First the dose constraints and penalty weights are determined by the clinicians, then the optimization problem is solved by linear programing. The dose constraints are usually fixed for each patient depending on the treated tumor site and the treatment planning guidelines followed. However, the clinicians select different penalty weights, leading to different optimization problems and finally adopt the one that results in the most desirable dose distribution. To remove the clinicians, influence on plan quality, reinforcement learning is explored.
Dosimetry for α- and β-emitting Radionuclide-based Therapies
Maryam Rahbaran, Ph.D. Student
Theranostics carrier molecules utilize a wide range of radionuclides, which emit α- and β- particles useful for killing cancer cells and emit photons useful for imaging with positron emission tomography (PET) or single-photon emission computed tomography (SPECT). Targeted radionuclide therapies used in theranostics and other applications with α- and β-emitting radionuclides have demonstrated safety and efficacy for targeting cancer cells while reducing doses to healthy tissue, in comparison to photons. Radioembolization with 90Y can be used to treat liver metastasis. It is a targeted internal radiation technique involving the use of a catheter to direct and administer microspheres containing radioisotopes into the chosen hepatic artery. In addition, for metastatic castration-resistant prostate cancer (mCRPC), β-emitting 177Lu-PSMA and α-emitting 225Ac-PSMA are used to treat micro-metastases in the body.
However, current radiobiological knowledge is based on photons, and the relative biological effectiveness (RBE) of α- and β- particles on cells is not well studied or reported. On a larger scale, many current clinical dosimetry tools for targeted radionuclide therapies are based on simplified phantom models, assuming no tissue heterogeneities and variations in patient-specific organ sizes. Voxel-based dosimetry methods are emerging for clinical use, however there is no consensus on how these tools should be used and commissioned. Imaging for radioembolization with 90Y is done with SPECT (using 99Tc), and each scan can take around 30 minutes to complete. As SPECT image information is essential for voxel-based dosimetry, a significant limitation of radioembolization is the motion of hepatic tumours during the SPECT scan due to patient breathing. Patient-specific dosimetry is not currently done for 177Lu-PSMA, and there is a need for a commissioning workflow for voxel-based clinical dosimetry software. Finally, patients treated with 177Lu-PSMA experience a variety of toxicities, and proper dosimetry may allow for the investigation of patient outcomes regarding accurate absorbed doses in organs at risk.
This project is divided in 5 major aims: (1) performing Monte Carlo-based dosimetry in a custom α-particle irradiation set-up, (2) performing Monte Carlo-based dosimetry in a custom β-particle irradiation set-up, (3) performing Monte Carlo-based dosimetry of 177Lu in 3D-printed kidney and parotid phantoms to compare to clinical software, (4) develop and image with SPECT and CT a 3D-printed patient-realistic breathing phantom of the lungs and liver to investigate the effect of motion on imaging and dosimetry and (5) performing organ-level and voxel-based retrospective dosimetry in patients treated with 177Lu to compare to dosimetry techniques and link dosimetry with patient outcomes.
Personalized Radioembolization Dosimetry
Maryam Rahbaran, Ph.D. Student
The standard dosimetry for radionuclide-based cancer treatments is traditionally based on the simplistic Medical Internal Radiation Dose (MIRD) formalism, which assumes a uniform radionuclide distribution and a uniform absorbed dose within the tumor. However, this assumption does not reflect the clinical reality, where tumors and surrounding tissues exhibit highly heterogeneous radionuclide uptake and dose distributions. A more accurate dosimetry framework must therefore account for both intra-tumoral heterogeneity and attenuation of radiation by patient-specific tissue structures.
The purpose of this project is to develop and validate an advanced image-based dosimetry software incorporating a Monte Carlo dose calculation engine. This software enables accurate and personalized dose estimates by modeling heterogeneous radionuclide uptake and tissue-dependent attenuation. While the toolkit may ultimately be applicable across a range of radionuclide therapies, this project focuses on radioembolization as the clinical use case.
Radioembolization is a targeted internal radiation therapy in which microspheres containing therapeutic radionuclides are administered through a micro-catheter and selectively deposited within hepatic arteries. These microspheres become permanently lodged, preferentially irradiating liver tumors while sparing surrounding healthy tissue. Traditionally performed with Yttrium-90 resin or glass microspheres, radioembolization can also be carried out using Holmium-166 (^166Ho) microspheres, which provide the added advantage of both therapeutic radiation and imaging capability.
The specific goal of this research is to improve radioembolization dosimetry by investigating and comparing three voxel-based dosimetry methods using Monte Carlo simulations. The accuracy and limitations of each method will be systematically evaluated against the conventional MIRD approach. Ultimately, this work aims to establish a robust and standardized methodology for accurate and patient-specific dosimetry, thereby improving treatment planning and clinical outcomes in liver-directed radionuclide therapy.
Dosimetry For the Morpheus Electronic Brachytherapy Source
Emma Raleigh-Smith, M.Sc. Student
This project focuses on verifying the accuracy and spatial distribution of radiation produced by the Morpheus electronic brachytherapy system (Empyrean, Boca Raton, FL). Monte Carlo simulations and experimental measurements will support more precise treatment planning for patients with skin, head and neck, and rectal cancers, ensuring the correct dose is delivered exaclty where needed.
Publications
2025
Cyr, Mélodie; Rahbaran, Maryam; Tomic, Nada; Enger, Shirin A
Dosimetric evaluation of unlaminated radiochromic films exposed to an Americium-241 source using measurements and Monte Carlo simulations Journal Article
In: Medical Physics, vol. 52, iss. 11, no. e70001, 2025, ISSN: 2473-4209.
@article{nokey,
title = {Dosimetric evaluation of unlaminated radiochromic films exposed to an Americium-241 source using measurements and Monte Carlo simulations},
author = {Mélodie Cyr and Maryam Rahbaran and Nada Tomic and Shirin A Enger},
doi = {10.1002/mp.70001},
issn = {2473-4209},
year = {2025},
date = {2025-10-27},
journal = {Medical Physics},
volume = {52},
number = {e70001},
issue = {11},
abstract = {Background: Radiochromic GafChromic film models are widely used in clinical settings for quality assurance during cancer treatment planning. Although these films are extensively studied in photon dosimetry, research on their application in α-particle dosimetry remains limited. With the growing use of α-particles in cancer therapy, it is important to establish film dosimetry protocols tailored to α-particles. Unlike photons, α-particles are charged, have a high linear energy transfer, and induce significantly greater biological damage, highlighting the need for specialized dosimetric approaches.
Purpose: This study aimed to evaluate the response of various unlaminated GafChromic film models including EBT3, EBT-XD, and HD-V2, irradiated with an 241Am α-particle source, with combined experimental film irradiation and Monte Carlo (MC) simulations.
Methods: In this study, unlaminated EBT3, EBT-XD, and HD-V2 film pieces were irradiated with an 241Am disk source at various exposure times within a dark box. A detailed comparison was performed across the three film models, focusing on uncertainties and relative dose errors. Film analysis was conducted using a custom Python script, extracting normalized pixel values from the green channel. Additionally, a MC-based user code was developed using the Geant4 simulation toolkit to model the 241Am source and calculate the dose rates in the active layers of the films and in water. The mean dose rates were also calculated in a 1 mm diameter region of interest. These simulated dose rates were employed to convert film exposure times into absorbed doses for both the active layers and water, establishing a reference dosimetry protocol for α-particles across the three radiochromic GafChromic film models.
Results: The mean dose rates within a 1 mm diameter circular region of interest in the active layers of the three unlaminated GafChromic film models were determined to be 3.77 ± 0.002 Gy/min for EBT3, 4.04 ± 0.0022 Gy/min for EBT-XD, and 4.25 ± 0.0017 Gy/min for HD-V2. When the film material was changed to water, the dose rate was increased 14.3% for EBT3, 19.2% for EBT-XD, and 15.0% for HD-V2, with EBT3 showing the closest match to water-equivalence. Calibration curves for each film model were generated by fitting a power function to their responses. Refinements to the dose range were necessary to achieve an uncertainty below the 5% threshold. Among the models, HD-V2 required the most adjustments to its dose range and exhibited the highest levels of experimental, fit, and total uncertainties, along with the largest relative dose errors.
Conclusions: This study investigated α-particle dosimetry protocols for unlaminated EBT3, EBT-XD, and HD-V2 GafChromic film models using experimental irradiations and MC simulations. Although EBT3 and EBT-XD demonstrate strong potential for α-particle quality assurance in treatment planning, the HD-V2 film model requires further investigation before it can be recommended for this application.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: Radiochromic GafChromic film models are widely used in clinical settings for quality assurance during cancer treatment planning. Although these films are extensively studied in photon dosimetry, research on their application in α-particle dosimetry remains limited. With the growing use of α-particles in cancer therapy, it is important to establish film dosimetry protocols tailored to α-particles. Unlike photons, α-particles are charged, have a high linear energy transfer, and induce significantly greater biological damage, highlighting the need for specialized dosimetric approaches.
Purpose: This study aimed to evaluate the response of various unlaminated GafChromic film models including EBT3, EBT-XD, and HD-V2, irradiated with an 241Am α-particle source, with combined experimental film irradiation and Monte Carlo (MC) simulations.
Methods: In this study, unlaminated EBT3, EBT-XD, and HD-V2 film pieces were irradiated with an 241Am disk source at various exposure times within a dark box. A detailed comparison was performed across the three film models, focusing on uncertainties and relative dose errors. Film analysis was conducted using a custom Python script, extracting normalized pixel values from the green channel. Additionally, a MC-based user code was developed using the Geant4 simulation toolkit to model the 241Am source and calculate the dose rates in the active layers of the films and in water. The mean dose rates were also calculated in a 1 mm diameter region of interest. These simulated dose rates were employed to convert film exposure times into absorbed doses for both the active layers and water, establishing a reference dosimetry protocol for α-particles across the three radiochromic GafChromic film models.
Results: The mean dose rates within a 1 mm diameter circular region of interest in the active layers of the three unlaminated GafChromic film models were determined to be 3.77 ± 0.002 Gy/min for EBT3, 4.04 ± 0.0022 Gy/min for EBT-XD, and 4.25 ± 0.0017 Gy/min for HD-V2. When the film material was changed to water, the dose rate was increased 14.3% for EBT3, 19.2% for EBT-XD, and 15.0% for HD-V2, with EBT3 showing the closest match to water-equivalence. Calibration curves for each film model were generated by fitting a power function to their responses. Refinements to the dose range were necessary to achieve an uncertainty below the 5% threshold. Among the models, HD-V2 required the most adjustments to its dose range and exhibited the highest levels of experimental, fit, and total uncertainties, along with the largest relative dose errors.
Conclusions: This study investigated α-particle dosimetry protocols for unlaminated EBT3, EBT-XD, and HD-V2 GafChromic film models using experimental irradiations and MC simulations. Although EBT3 and EBT-XD demonstrate strong potential for α-particle quality assurance in treatment planning, the HD-V2 film model requires further investigation before it can be recommended for this application.
Purpose: This study aimed to evaluate the response of various unlaminated GafChromic film models including EBT3, EBT-XD, and HD-V2, irradiated with an 241Am α-particle source, with combined experimental film irradiation and Monte Carlo (MC) simulations.
Methods: In this study, unlaminated EBT3, EBT-XD, and HD-V2 film pieces were irradiated with an 241Am disk source at various exposure times within a dark box. A detailed comparison was performed across the three film models, focusing on uncertainties and relative dose errors. Film analysis was conducted using a custom Python script, extracting normalized pixel values from the green channel. Additionally, a MC-based user code was developed using the Geant4 simulation toolkit to model the 241Am source and calculate the dose rates in the active layers of the films and in water. The mean dose rates were also calculated in a 1 mm diameter region of interest. These simulated dose rates were employed to convert film exposure times into absorbed doses for both the active layers and water, establishing a reference dosimetry protocol for α-particles across the three radiochromic GafChromic film models.
Results: The mean dose rates within a 1 mm diameter circular region of interest in the active layers of the three unlaminated GafChromic film models were determined to be 3.77 ± 0.002 Gy/min for EBT3, 4.04 ± 0.0022 Gy/min for EBT-XD, and 4.25 ± 0.0017 Gy/min for HD-V2. When the film material was changed to water, the dose rate was increased 14.3% for EBT3, 19.2% for EBT-XD, and 15.0% for HD-V2, with EBT3 showing the closest match to water-equivalence. Calibration curves for each film model were generated by fitting a power function to their responses. Refinements to the dose range were necessary to achieve an uncertainty below the 5% threshold. Among the models, HD-V2 required the most adjustments to its dose range and exhibited the highest levels of experimental, fit, and total uncertainties, along with the largest relative dose errors.
Conclusions: This study investigated α-particle dosimetry protocols for unlaminated EBT3, EBT-XD, and HD-V2 GafChromic film models using experimental irradiations and MC simulations. Although EBT3 and EBT-XD demonstrate strong potential for α-particle quality assurance in treatment planning, the HD-V2 film model requires further investigation before it can be recommended for this application.
Quetin, Sébastien; Jafarzadeh, Hossein; Kalinowski, Jonathan; Bekerat, Hamed; Bahoric, Boris; Maleki, Farhad; Enger, Shirin A.
Automatic catheter digitization in breast brachytherapy Journal Article
In: Medical Physics, vol. 52, iss. 9, no. e18107, 2025, ISSN: 2473-4209.
@article{nokey,
title = {Automatic catheter digitization in breast brachytherapy},
author = {Sébastien Quetin and Hossein Jafarzadeh and Jonathan Kalinowski and Hamed Bekerat and Boris Bahoric and Farhad Maleki and Shirin A. Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.18107},
doi = {https://doi.org/10.1002/mp.18107},
issn = {2473-4209},
year = {2025},
date = {2025-09-12},
urldate = {2025-09-12},
journal = {Medical Physics},
volume = {52},
number = {e18107},
issue = {9},
abstract = {Background:
High dose rate (HDR) brachytherapy requires clinicians to digitize catheters manually. This process is time-consuming, complex, and depends heavily on clinical experience-especially in breast cancer cases, where catheters may be inserted at varying angles and orientations due to an irregular anatomy.
Purpose:
This study is the first to automate catheter digitization specifically for breast HDR brachytherapy, emphasizing the unique challenges associated with this treatment site. It also introduces a pipeline that automatically digitizes catheters, generates dwell positions, and calculates the delivered dose for new breast cancer patients.
Methods:
Treatment data from 117 breast cancer patients treated with HDR brachytherapy were used. Pseudo-contours for the catheters were created from the treatment digitization points and divided into three classes: catheter body, catheter head, and catheter tip. An nnU-Net pipeline was trained to segment the pseudo-contours on treatment planning computed tomography images of 88 patients (training and validation). Then, pseudo-contours were digitized by separating the catheters into connected components. Predicted catheters with an unusual volume were flagged for manual review. A custom algorithm was designed to report and separate connected components containing colliding catheters. Finally, a spline was fitted to every separated catheter, and the tip was identified on the spline using the tip contour prediction. Dwell positions were placed from the created tip at a regular step size extracted from the DICOM plan file. Distance from each dwell position used during the clinical treatment to the fitted spline (shaft distance) was computed, as well as the distance from the treatment tip to the one identified by our pipeline. Dwell times from the clinical plan were assigned to the nearest generated dwell positions. TG-43 dose in water was computed analytically, and the absorbed dose in the medium was predicted using a published AI-based dose prediction model. Dosimetric comparison between the clinically delivered plan dose and the created automated plan dose was evaluated regarding dosimetric indices percent error.
Results:
Our pipeline was used to digitize 408 catheters on a test set of 29 patients. Shaft distance was on average 0.70 ± 3.91 mm and distance to the tip was on average 1.37 ± 5.25 mm. The dosimetric error between the manual and automated treatment plans was, on average, below 3% for planning target volume V100, V150, V200 and for the lung, heart, skin, and chest wall D2cc and D1cc, in both water and heterogeneous media. For D0.1cc values in all the organs at risk, the average error remained below 5%. The pipeline execution time, including auto-contouring, digitization, and dose to medium prediction, averages 118 s, ranging from 63 to 294 s. The pipeline successfully flagged all cases where digitization was not performed correctly.
Conclusions:
Our pipeline is the first to automate the digitization of catheters for breast brachytherapy, as well as the first to generate dwell positions and predict corresponding AI-based absorbed dose to medium based on automatically digitized catheters. The automatically digitized catheters are in excellent agreement with the manually digitized ones while more accurately reflecting their true anatomical shape.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background:
High dose rate (HDR) brachytherapy requires clinicians to digitize catheters manually. This process is time-consuming, complex, and depends heavily on clinical experience-especially in breast cancer cases, where catheters may be inserted at varying angles and orientations due to an irregular anatomy.
Purpose:
This study is the first to automate catheter digitization specifically for breast HDR brachytherapy, emphasizing the unique challenges associated with this treatment site. It also introduces a pipeline that automatically digitizes catheters, generates dwell positions, and calculates the delivered dose for new breast cancer patients.
Methods:
Treatment data from 117 breast cancer patients treated with HDR brachytherapy were used. Pseudo-contours for the catheters were created from the treatment digitization points and divided into three classes: catheter body, catheter head, and catheter tip. An nnU-Net pipeline was trained to segment the pseudo-contours on treatment planning computed tomography images of 88 patients (training and validation). Then, pseudo-contours were digitized by separating the catheters into connected components. Predicted catheters with an unusual volume were flagged for manual review. A custom algorithm was designed to report and separate connected components containing colliding catheters. Finally, a spline was fitted to every separated catheter, and the tip was identified on the spline using the tip contour prediction. Dwell positions were placed from the created tip at a regular step size extracted from the DICOM plan file. Distance from each dwell position used during the clinical treatment to the fitted spline (shaft distance) was computed, as well as the distance from the treatment tip to the one identified by our pipeline. Dwell times from the clinical plan were assigned to the nearest generated dwell positions. TG-43 dose in water was computed analytically, and the absorbed dose in the medium was predicted using a published AI-based dose prediction model. Dosimetric comparison between the clinically delivered plan dose and the created automated plan dose was evaluated regarding dosimetric indices percent error.
Results:
Our pipeline was used to digitize 408 catheters on a test set of 29 patients. Shaft distance was on average 0.70 ± 3.91 mm and distance to the tip was on average 1.37 ± 5.25 mm. The dosimetric error between the manual and automated treatment plans was, on average, below 3% for planning target volume V100, V150, V200 and for the lung, heart, skin, and chest wall D2cc and D1cc, in both water and heterogeneous media. For D0.1cc values in all the organs at risk, the average error remained below 5%. The pipeline execution time, including auto-contouring, digitization, and dose to medium prediction, averages 118 s, ranging from 63 to 294 s. The pipeline successfully flagged all cases where digitization was not performed correctly.
Conclusions:
Our pipeline is the first to automate the digitization of catheters for breast brachytherapy, as well as the first to generate dwell positions and predict corresponding AI-based absorbed dose to medium based on automatically digitized catheters. The automatically digitized catheters are in excellent agreement with the manually digitized ones while more accurately reflecting their true anatomical shape.
High dose rate (HDR) brachytherapy requires clinicians to digitize catheters manually. This process is time-consuming, complex, and depends heavily on clinical experience-especially in breast cancer cases, where catheters may be inserted at varying angles and orientations due to an irregular anatomy.
Purpose:
This study is the first to automate catheter digitization specifically for breast HDR brachytherapy, emphasizing the unique challenges associated with this treatment site. It also introduces a pipeline that automatically digitizes catheters, generates dwell positions, and calculates the delivered dose for new breast cancer patients.
Methods:
Treatment data from 117 breast cancer patients treated with HDR brachytherapy were used. Pseudo-contours for the catheters were created from the treatment digitization points and divided into three classes: catheter body, catheter head, and catheter tip. An nnU-Net pipeline was trained to segment the pseudo-contours on treatment planning computed tomography images of 88 patients (training and validation). Then, pseudo-contours were digitized by separating the catheters into connected components. Predicted catheters with an unusual volume were flagged for manual review. A custom algorithm was designed to report and separate connected components containing colliding catheters. Finally, a spline was fitted to every separated catheter, and the tip was identified on the spline using the tip contour prediction. Dwell positions were placed from the created tip at a regular step size extracted from the DICOM plan file. Distance from each dwell position used during the clinical treatment to the fitted spline (shaft distance) was computed, as well as the distance from the treatment tip to the one identified by our pipeline. Dwell times from the clinical plan were assigned to the nearest generated dwell positions. TG-43 dose in water was computed analytically, and the absorbed dose in the medium was predicted using a published AI-based dose prediction model. Dosimetric comparison between the clinically delivered plan dose and the created automated plan dose was evaluated regarding dosimetric indices percent error.
Results:
Our pipeline was used to digitize 408 catheters on a test set of 29 patients. Shaft distance was on average 0.70 ± 3.91 mm and distance to the tip was on average 1.37 ± 5.25 mm. The dosimetric error between the manual and automated treatment plans was, on average, below 3% for planning target volume V100, V150, V200 and for the lung, heart, skin, and chest wall D2cc and D1cc, in both water and heterogeneous media. For D0.1cc values in all the organs at risk, the average error remained below 5%. The pipeline execution time, including auto-contouring, digitization, and dose to medium prediction, averages 118 s, ranging from 63 to 294 s. The pipeline successfully flagged all cases where digitization was not performed correctly.
Conclusions:
Our pipeline is the first to automate the digitization of catheters for breast brachytherapy, as well as the first to generate dwell positions and predict corresponding AI-based absorbed dose to medium based on automatically digitized catheters. The automatically digitized catheters are in excellent agreement with the manually digitized ones while more accurately reflecting their true anatomical shape.
Kalinowski, Jonathan; Tal, Oren; Reid, Jake; 3rd, John Munro; Moran, Matthew; Armstrong, Andrea; Enger, Shirin A.
Development and characterization of a prototype selenium-75 high dose rate brachytherapy source Journal Article
In: Medical Physics, vol. 52, iss. 9, no. e18088, 2025, ISSN: 2473-4209.
@article{nokey,
title = {Development and characterization of a prototype selenium-75 high dose rate brachytherapy source},
author = {Jonathan Kalinowski and Oren Tal and Jake Reid and John Munro 3rd and Matthew Moran and Andrea Armstrong and Shirin A. Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.18088},
doi = { https://doi.org/10.1002/mp.18088},
issn = {2473-4209},
year = {2025},
date = {2025-09-09},
urldate = {2025-09-09},
journal = {Medical Physics},
volume = {52},
number = {e18088},
issue = {9},
abstract = {Background:
75Se (t1/2 ≈ 120 days, Eγ,avg ≈ 215 keV) offers advantages over 192Ir (t1/2 ≈ 74 days, Eγ,avg ≈ 360 keV) as a high dose rate brachytherapy source due to its lower gamma energy and longer half-life. Despite its widespread use in industrial gamma radiography, a 75Se brachytherapy source has yet to be manufactured.
Purpose:
A novel 75Se-based source design with a vanadium diselenide core, titled the SeCure source, was proposed. This study aimed to evaluate the feasibility of this source design for dosimetry and manufacturability purposes and to develop an activated prototype source.
Methods:
The source was modeled and integrated into the Monte Carlo-based treatment planning system RapidBrachyMCTPS, where its TG-43U1 parameters, photon spectrum, and broad beam first half-value layers (HVL1) and tenth-value layers (TVL1) in lead, tungsten, and concrete were calculated. A prototype source was manufactured, and the vanadium diselenide content of the capsule was verified with neutron radiography. The source was then activated to a nominal activity of 8.5 ± 0.9 mCi at the McMaster Nuclear Reactor. The activity was measured with two separate dose calibrators. Gamma spectroscopy was used to characterize any activated radioactive contaminants in the source, and wipe testing was performed to check for any leakage of 75Se from the encapsulation.
Results:
The SeCure source's TG-43U1 parameters were computed, showing that 2.056 ± 0.003 times the activity of 75Se is required relative to 192Ir to achieve the same dose rate in water at (1 cm, 90°). The mean spectral energy of the source is 214.695 ± 0.005 keV, resulting in reduced first half-value and tenth-value layers relative to 192Ir in attenuating materials. For example, the HVL1 was reduced from 2.795 ± 0.002 mm to 1.020 ± 0.001 mm in lead, from 2.049 ± 0.002 mm to 0.752 ± 0.001 mm in tungsten, and from 70.63 ± 0.04 mm to 61.37 ± 0.03 mm in concrete. The activated source achieved the desired activity, indicated as 9.2 ± 0.2 mCi and 8.5 ± 0.9 mCi at the end of irradiation on the two dose calibrators. All identified radionuclide contaminants decaying below 0.1% of the 75Se activity after 5 days post-irradiation. Wipe testing only identified radioactive contaminants present in activated titanium, with only 1.24 ± 0.01 × 10−7 mCi of 24Na detected 72 h post-irradiation, indicating that the integrity of the encapsulation was maintained.
Conclusions:
The SeCure design possesses the dosimetric, spectral, and physical properties necessary for a feasible high dose rate brachytherapy source. Next, manufacturing of a high-activity SeCure source will be pursued.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background:
75Se (t1/2 ≈ 120 days, Eγ,avg ≈ 215 keV) offers advantages over 192Ir (t1/2 ≈ 74 days, Eγ,avg ≈ 360 keV) as a high dose rate brachytherapy source due to its lower gamma energy and longer half-life. Despite its widespread use in industrial gamma radiography, a 75Se brachytherapy source has yet to be manufactured.
Purpose:
A novel 75Se-based source design with a vanadium diselenide core, titled the SeCure source, was proposed. This study aimed to evaluate the feasibility of this source design for dosimetry and manufacturability purposes and to develop an activated prototype source.
Methods:
The source was modeled and integrated into the Monte Carlo-based treatment planning system RapidBrachyMCTPS, where its TG-43U1 parameters, photon spectrum, and broad beam first half-value layers (HVL1) and tenth-value layers (TVL1) in lead, tungsten, and concrete were calculated. A prototype source was manufactured, and the vanadium diselenide content of the capsule was verified with neutron radiography. The source was then activated to a nominal activity of 8.5 ± 0.9 mCi at the McMaster Nuclear Reactor. The activity was measured with two separate dose calibrators. Gamma spectroscopy was used to characterize any activated radioactive contaminants in the source, and wipe testing was performed to check for any leakage of 75Se from the encapsulation.
Results:
The SeCure source's TG-43U1 parameters were computed, showing that 2.056 ± 0.003 times the activity of 75Se is required relative to 192Ir to achieve the same dose rate in water at (1 cm, 90°). The mean spectral energy of the source is 214.695 ± 0.005 keV, resulting in reduced first half-value and tenth-value layers relative to 192Ir in attenuating materials. For example, the HVL1 was reduced from 2.795 ± 0.002 mm to 1.020 ± 0.001 mm in lead, from 2.049 ± 0.002 mm to 0.752 ± 0.001 mm in tungsten, and from 70.63 ± 0.04 mm to 61.37 ± 0.03 mm in concrete. The activated source achieved the desired activity, indicated as 9.2 ± 0.2 mCi and 8.5 ± 0.9 mCi at the end of irradiation on the two dose calibrators. All identified radionuclide contaminants decaying below 0.1% of the 75Se activity after 5 days post-irradiation. Wipe testing only identified radioactive contaminants present in activated titanium, with only 1.24 ± 0.01 × 10−7 mCi of 24Na detected 72 h post-irradiation, indicating that the integrity of the encapsulation was maintained.
Conclusions:
The SeCure design possesses the dosimetric, spectral, and physical properties necessary for a feasible high dose rate brachytherapy source. Next, manufacturing of a high-activity SeCure source will be pursued.
75Se (t1/2 ≈ 120 days, Eγ,avg ≈ 215 keV) offers advantages over 192Ir (t1/2 ≈ 74 days, Eγ,avg ≈ 360 keV) as a high dose rate brachytherapy source due to its lower gamma energy and longer half-life. Despite its widespread use in industrial gamma radiography, a 75Se brachytherapy source has yet to be manufactured.
Purpose:
A novel 75Se-based source design with a vanadium diselenide core, titled the SeCure source, was proposed. This study aimed to evaluate the feasibility of this source design for dosimetry and manufacturability purposes and to develop an activated prototype source.
Methods:
The source was modeled and integrated into the Monte Carlo-based treatment planning system RapidBrachyMCTPS, where its TG-43U1 parameters, photon spectrum, and broad beam first half-value layers (HVL1) and tenth-value layers (TVL1) in lead, tungsten, and concrete were calculated. A prototype source was manufactured, and the vanadium diselenide content of the capsule was verified with neutron radiography. The source was then activated to a nominal activity of 8.5 ± 0.9 mCi at the McMaster Nuclear Reactor. The activity was measured with two separate dose calibrators. Gamma spectroscopy was used to characterize any activated radioactive contaminants in the source, and wipe testing was performed to check for any leakage of 75Se from the encapsulation.
Results:
The SeCure source's TG-43U1 parameters were computed, showing that 2.056 ± 0.003 times the activity of 75Se is required relative to 192Ir to achieve the same dose rate in water at (1 cm, 90°). The mean spectral energy of the source is 214.695 ± 0.005 keV, resulting in reduced first half-value and tenth-value layers relative to 192Ir in attenuating materials. For example, the HVL1 was reduced from 2.795 ± 0.002 mm to 1.020 ± 0.001 mm in lead, from 2.049 ± 0.002 mm to 0.752 ± 0.001 mm in tungsten, and from 70.63 ± 0.04 mm to 61.37 ± 0.03 mm in concrete. The activated source achieved the desired activity, indicated as 9.2 ± 0.2 mCi and 8.5 ± 0.9 mCi at the end of irradiation on the two dose calibrators. All identified radionuclide contaminants decaying below 0.1% of the 75Se activity after 5 days post-irradiation. Wipe testing only identified radioactive contaminants present in activated titanium, with only 1.24 ± 0.01 × 10−7 mCi of 24Na detected 72 h post-irradiation, indicating that the integrity of the encapsulation was maintained.
Conclusions:
The SeCure design possesses the dosimetric, spectral, and physical properties necessary for a feasible high dose rate brachytherapy source. Next, manufacturing of a high-activity SeCure source will be pursued.
Dumančić, Mirta; Kalinowski, Jonathan; Diaz-Martinez, Victor D; Li, Joanna; Behmand, Behnaz; DeCunha, Joseph M; Enger, Shirin A
Microdosimetry calculations in situ for clinically relevant photon sources and their correlation with the early DNA damage response Journal Article
In: Medical Physics, vol. 52, iss. 7, no. e17979, 2025, ISSN: 2473-4209.
@article{nokey,
title = {Microdosimetry calculations in situ for clinically relevant photon sources and their correlation with the early DNA damage response},
author = {Mirta Dumančić and Jonathan Kalinowski and Victor D Diaz-Martinez and Joanna Li and Behnaz Behmand and Joseph M DeCunha and Shirin A Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17979},
doi = {10.1002/mp.17979},
issn = {2473-4209},
year = {2025},
date = {2025-07-15},
urldate = {2025-07-15},
journal = {Medical Physics},
volume = {52},
number = {e17979},
issue = {7},
abstract = {Background:
Radiobiological data suggests variations in relative biological effectiveness (RBE) between clinically used photon-based sources. A microdosimetric formalism using Monte Carlo (MC) methods can mechanistically describe the photon RBE. Experimentally derived RBE based on DNA double-strand breaks (RBEDSB) has been shown to scale with the microdosimetry quantity dose-mean lineal energy (yD).
Purpose:
To calculate microdosimetric spectra for clinically relevant photon sources, spanning from soft x-rays produced by a 50 kVp x-ray source through various brachytherapy sources up to a 6 MV medical linac. Furthermore, we investigated the correlation between RBEDSB and yD of different photon sources.
Methods:
Photon sources simulated include low-energy x-rays (50 kVp), orthovoltage x-rays (225 kVp), high-dose-rate brachytherapy sources (75Se, 192Ir and 60Co), and a 6 MV medical linac. Secondary electron spectra at the cellular level were calculated for in vitro cell irradiation setups using Geant4 MC-based packages, RapidBrachyMCTPS and RapidExternalBeam. The obtained spectra were used in MicroDose, a microdosimetry simulation software, to obtain microdosimetric quantities, including single-event lineal energy (y) and specific energy (z) spectra, and dose-mean and frequency-mean quantities (yF, yD, zsF, zsD). Uniform spherical targets (1–14 μm radius) and realistic HeLa and PC3 cell nucleus models were simulated using cell size data obtained from literature and nuclei size data from confocal microscopy imaging. Radiobiological experiments using γH2AX foci quantified DNA double-strand breaks for HeLa and PC3 cells after irradiations with 50 and 225 kVp, 192Ir, and 6 MV linac, and RBEDSB was determined using 225 kVp as the reference.
Results:
The calculated yD (yF) is within the 3.5–1.2 keV/μm range (1.8–0.2 keV/μm) for 1 μm simulated target size between the lowest energy 50 kVp x-ray source and the highest energy 6 MV linac source, respectively. For the HeLa and PC3 cell nuclei models based on microscopy data, yD (yF) spans from 1.6 to 0.6 keV/μm (0.7 to 0.2 keV/μm). When compared between different target sizes, yD (yF) ranges from 3.5 to 1.0 (1.8–0.4) keV/μm between 1 and 10 μm radius targets for the 50 kVp x-ray source. A smaller change is observed for 6 MV linac, ranging from 1.2 to 0.5 keV/μm and 0.23 to 0.22 keV/μm for yD and yF, respectively. For the simulated 75Se source currently under investigation, the calculated yD values are 11%–24% higher relative to those of 192Ir in the range of target sizes between 1 and 14 μm in radius. RBEDSB for HeLa cells was 1.4 ± 0.7 for 50 kVp x-rays, 0.5 ± 0.2 for 192Ir, and 0.7 ± 0.4 for 6 MV linac irradiations. For PC3 cells, RBEDSB was 1.3 ± 0.6, 0.8 ± 0.4 and 0.5 ± 0.3 for 50 kVp, 192Ir and 6 MV linac, respectively. Measured RBEDSB values are consistent with yD ratios of the corresponding photon sources for HeLa and PC3 nucleus models.
Conclusions:
Microdosimetric spectra strongly depend on the simulated energy of photon sources and target size, with yD and zsD decreasing by a factor of ≈2–3 between diagnostic 50 kVp and 6 MV therapeutic x-rays for target sizes from 1–14 μm in radius. The early damage RBEDSB indicates this stochastic change in energy density between various photon sources as the yields of γH2AX foci per nucleus scale with yD of the source.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background:
Radiobiological data suggests variations in relative biological effectiveness (RBE) between clinically used photon-based sources. A microdosimetric formalism using Monte Carlo (MC) methods can mechanistically describe the photon RBE. Experimentally derived RBE based on DNA double-strand breaks (RBEDSB) has been shown to scale with the microdosimetry quantity dose-mean lineal energy (yD).
Purpose:
To calculate microdosimetric spectra for clinically relevant photon sources, spanning from soft x-rays produced by a 50 kVp x-ray source through various brachytherapy sources up to a 6 MV medical linac. Furthermore, we investigated the correlation between RBEDSB and yD of different photon sources.
Methods:
Photon sources simulated include low-energy x-rays (50 kVp), orthovoltage x-rays (225 kVp), high-dose-rate brachytherapy sources (75Se, 192Ir and 60Co), and a 6 MV medical linac. Secondary electron spectra at the cellular level were calculated for in vitro cell irradiation setups using Geant4 MC-based packages, RapidBrachyMCTPS and RapidExternalBeam. The obtained spectra were used in MicroDose, a microdosimetry simulation software, to obtain microdosimetric quantities, including single-event lineal energy (y) and specific energy (z) spectra, and dose-mean and frequency-mean quantities (yF, yD, zsF, zsD). Uniform spherical targets (1–14 μm radius) and realistic HeLa and PC3 cell nucleus models were simulated using cell size data obtained from literature and nuclei size data from confocal microscopy imaging. Radiobiological experiments using γH2AX foci quantified DNA double-strand breaks for HeLa and PC3 cells after irradiations with 50 and 225 kVp, 192Ir, and 6 MV linac, and RBEDSB was determined using 225 kVp as the reference.
Results:
The calculated yD (yF) is within the 3.5–1.2 keV/μm range (1.8–0.2 keV/μm) for 1 μm simulated target size between the lowest energy 50 kVp x-ray source and the highest energy 6 MV linac source, respectively. For the HeLa and PC3 cell nuclei models based on microscopy data, yD (yF) spans from 1.6 to 0.6 keV/μm (0.7 to 0.2 keV/μm). When compared between different target sizes, yD (yF) ranges from 3.5 to 1.0 (1.8–0.4) keV/μm between 1 and 10 μm radius targets for the 50 kVp x-ray source. A smaller change is observed for 6 MV linac, ranging from 1.2 to 0.5 keV/μm and 0.23 to 0.22 keV/μm for yD and yF, respectively. For the simulated 75Se source currently under investigation, the calculated yD values are 11%–24% higher relative to those of 192Ir in the range of target sizes between 1 and 14 μm in radius. RBEDSB for HeLa cells was 1.4 ± 0.7 for 50 kVp x-rays, 0.5 ± 0.2 for 192Ir, and 0.7 ± 0.4 for 6 MV linac irradiations. For PC3 cells, RBEDSB was 1.3 ± 0.6, 0.8 ± 0.4 and 0.5 ± 0.3 for 50 kVp, 192Ir and 6 MV linac, respectively. Measured RBEDSB values are consistent with yD ratios of the corresponding photon sources for HeLa and PC3 nucleus models.
Conclusions:
Microdosimetric spectra strongly depend on the simulated energy of photon sources and target size, with yD and zsD decreasing by a factor of ≈2–3 between diagnostic 50 kVp and 6 MV therapeutic x-rays for target sizes from 1–14 μm in radius. The early damage RBEDSB indicates this stochastic change in energy density between various photon sources as the yields of γH2AX foci per nucleus scale with yD of the source.
Radiobiological data suggests variations in relative biological effectiveness (RBE) between clinically used photon-based sources. A microdosimetric formalism using Monte Carlo (MC) methods can mechanistically describe the photon RBE. Experimentally derived RBE based on DNA double-strand breaks (RBEDSB) has been shown to scale with the microdosimetry quantity dose-mean lineal energy (yD).
Purpose:
To calculate microdosimetric spectra for clinically relevant photon sources, spanning from soft x-rays produced by a 50 kVp x-ray source through various brachytherapy sources up to a 6 MV medical linac. Furthermore, we investigated the correlation between RBEDSB and yD of different photon sources.
Methods:
Photon sources simulated include low-energy x-rays (50 kVp), orthovoltage x-rays (225 kVp), high-dose-rate brachytherapy sources (75Se, 192Ir and 60Co), and a 6 MV medical linac. Secondary electron spectra at the cellular level were calculated for in vitro cell irradiation setups using Geant4 MC-based packages, RapidBrachyMCTPS and RapidExternalBeam. The obtained spectra were used in MicroDose, a microdosimetry simulation software, to obtain microdosimetric quantities, including single-event lineal energy (y) and specific energy (z) spectra, and dose-mean and frequency-mean quantities (yF, yD, zsF, zsD). Uniform spherical targets (1–14 μm radius) and realistic HeLa and PC3 cell nucleus models were simulated using cell size data obtained from literature and nuclei size data from confocal microscopy imaging. Radiobiological experiments using γH2AX foci quantified DNA double-strand breaks for HeLa and PC3 cells after irradiations with 50 and 225 kVp, 192Ir, and 6 MV linac, and RBEDSB was determined using 225 kVp as the reference.
Results:
The calculated yD (yF) is within the 3.5–1.2 keV/μm range (1.8–0.2 keV/μm) for 1 μm simulated target size between the lowest energy 50 kVp x-ray source and the highest energy 6 MV linac source, respectively. For the HeLa and PC3 cell nuclei models based on microscopy data, yD (yF) spans from 1.6 to 0.6 keV/μm (0.7 to 0.2 keV/μm). When compared between different target sizes, yD (yF) ranges from 3.5 to 1.0 (1.8–0.4) keV/μm between 1 and 10 μm radius targets for the 50 kVp x-ray source. A smaller change is observed for 6 MV linac, ranging from 1.2 to 0.5 keV/μm and 0.23 to 0.22 keV/μm for yD and yF, respectively. For the simulated 75Se source currently under investigation, the calculated yD values are 11%–24% higher relative to those of 192Ir in the range of target sizes between 1 and 14 μm in radius. RBEDSB for HeLa cells was 1.4 ± 0.7 for 50 kVp x-rays, 0.5 ± 0.2 for 192Ir, and 0.7 ± 0.4 for 6 MV linac irradiations. For PC3 cells, RBEDSB was 1.3 ± 0.6, 0.8 ± 0.4 and 0.5 ± 0.3 for 50 kVp, 192Ir and 6 MV linac, respectively. Measured RBEDSB values are consistent with yD ratios of the corresponding photon sources for HeLa and PC3 nucleus models.
Conclusions:
Microdosimetric spectra strongly depend on the simulated energy of photon sources and target size, with yD and zsD decreasing by a factor of ≈2–3 between diagnostic 50 kVp and 6 MV therapeutic x-rays for target sizes from 1–14 μm in radius. The early damage RBEDSB indicates this stochastic change in energy density between various photon sources as the yields of γH2AX foci per nucleus scale with yD of the source.
Rahbaran, Maryam; Li, Joanna; Enger, Shirin A.
Monte Carlo-based dosimetry and optimization of a custom alpha cell irradiation setup Journal Article
In: Physics in Medicine & Biology, vol. 70, iss. 13, no. 135011, 2025, ISSN: 1361-6560.
@article{nokey,
title = {Monte Carlo-based dosimetry and optimization of a custom alpha cell irradiation setup},
author = {Maryam Rahbaran and Joanna Li and Shirin A. Enger},
url = {https://iopscience.iop.org/article/10.1088/1361-6560/ade846},
doi = {10.1088/1361-6560/ade846},
issn = {1361-6560},
year = {2025},
date = {2025-07-03},
journal = {Physics in Medicine & Biology},
volume = {70},
number = {135011},
issue = {13},
abstract = {Objective.When combined with targeting agents,α-particle-emitting radionuclides show promise in treating hypoxic tumors and micrometastases. These radionuclides exhibit a high relative biological effectiveness (RBE), attributed to their high linear energy transfer, and induce complex DNA damage within targeted cells. However, most clinical experience and radiobiological data are derived from photon irradiation. To optimizeα-particle-based treatments, further research is needed to refine their RBE estimates. This study aimed to characterize and optimize a customin-vitrocell irradiation setup forα-particle RBE studies using241Am through Monte Carlo simulations.Approach.A Geant4-based Monte Carlo simulation model was used to simulate a custom cell well setup. An241Am (48 kBq) source was positioned beneath the well with an adjustable source-to-surface distance (SSD). The spectra of decay products was calculated with 6.5×109simulated241Am decay events. Simulations were conducted for SSD values of 2 mm, 5 mm, and 7 mm under three scenarios: (A) total dose rate from all decay products, (B) excludingγ-emissions, and (C) excluding secondary particles. Results were compared to published spectra and a published dose rate (0.1 Gy min-1) as validation.Main results.The validation dose rate was 0.1136 Gy min-1. Photons of 13.9-59.5 keV andα-particles of 5.39-5.48 MeV were observed. The dose inhomogeneity across the cells was around 30%, 10%, and 5% in the 2, 5, and 7 mm SSD setups, respectively. The corresponding total dose rates in cells for the three SSDs were 0.583, 0.146, and 0.0830 Gy min-1. The dose rate contributions were 90% fromα-particles, less than 0.07% fromγ-emissions, and 9%-10% from secondary particles.Significance.To accurately assess radiobiological effects, it is important to consider the full decay spectrum of radionuclides and their secondary particles in dosimetry calculations. These findings will aid in refining experimental setups for futurein-vitrostudies, contributing to more reliable RBE calculations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective.When combined with targeting agents,α-particle-emitting radionuclides show promise in treating hypoxic tumors and micrometastases. These radionuclides exhibit a high relative biological effectiveness (RBE), attributed to their high linear energy transfer, and induce complex DNA damage within targeted cells. However, most clinical experience and radiobiological data are derived from photon irradiation. To optimizeα-particle-based treatments, further research is needed to refine their RBE estimates. This study aimed to characterize and optimize a customin-vitrocell irradiation setup forα-particle RBE studies using241Am through Monte Carlo simulations.Approach.A Geant4-based Monte Carlo simulation model was used to simulate a custom cell well setup. An241Am (48 kBq) source was positioned beneath the well with an adjustable source-to-surface distance (SSD). The spectra of decay products was calculated with 6.5×109simulated241Am decay events. Simulations were conducted for SSD values of 2 mm, 5 mm, and 7 mm under three scenarios: (A) total dose rate from all decay products, (B) excludingγ-emissions, and (C) excluding secondary particles. Results were compared to published spectra and a published dose rate (0.1 Gy min-1) as validation.Main results.The validation dose rate was 0.1136 Gy min-1. Photons of 13.9-59.5 keV andα-particles of 5.39-5.48 MeV were observed. The dose inhomogeneity across the cells was around 30%, 10%, and 5% in the 2, 5, and 7 mm SSD setups, respectively. The corresponding total dose rates in cells for the three SSDs were 0.583, 0.146, and 0.0830 Gy min-1. The dose rate contributions were 90% fromα-particles, less than 0.07% fromγ-emissions, and 9%-10% from secondary particles.Significance.To accurately assess radiobiological effects, it is important to consider the full decay spectrum of radionuclides and their secondary particles in dosimetry calculations. These findings will aid in refining experimental setups for futurein-vitrostudies, contributing to more reliable RBE calculations.
Morén, Björn; Jafarzadeh, Hossein; Enger, Shirin A
A data-driven approach to model spatial dose characteristics for catheter placement of high dose-rate brachytherapy for prostate cancer Journal Article
In: Computers in Biology and Medicine, vol. 190, no. 110020, 2025, ISSN: 1879-0534.
@article{nokey,
title = {A data-driven approach to model spatial dose characteristics for catheter placement of high dose-rate brachytherapy for prostate cancer},
author = {Björn Morén and Hossein Jafarzadeh and Shirin A Enger},
url = {https://www.sciencedirect.com/science/article/pii/S0010482525003713?via%3Dihub},
doi = {https://doi.org/10.1016/j.compbiomed.2025.110020},
issn = {1879-0534},
year = {2025},
date = {2025-05-01},
journal = {Computers in Biology and Medicine},
volume = {190},
number = {110020},
abstract = {Background: High dose rate brachytherapy (HDR BT) is a common treatment modality for cancer. In HDR BT, a radioactive source is placed inside or close to a tumor, aiming to give a high enough dose to the tumor, while sparing nearby healthy tissue and organs at risk. Treatment planning of HDR BT for prostate cancer consists of two types of decisions, placement of catheters, modeled with binary variables, and dwell times, modeled with continuous non-negative variables. Optimal spatial placement of catheters is important for avoiding local recurrence and complications, but such characteristics have not been modeled for the combined treatment planning problem of catheter placement and dwell time optimization.
Method: We propose a data-driven approach using linear regression, mutual information, and random forests to find convex estimates of spatial dose characteristics that correlate well with contiguous volumes receiving a too-high (hot spots) or too-low dose (cold spots). These estimates were incorporated in retrospective treatment plan optimization of 28 prostate cancer patients.
Results: The proposed hot-spot terms reduced the volume receiving twice the prescribed dose by 29% at 14 catheters. Also, the results illustrate the trade-offs between the number of catheters and spatial dose characteristics.
Conclusions: Our study demonstrates that incorporating a term for hot spots in the objective function of the treatment planning model is more effective in reducing hot spots than catheter placements that are not optimized for hot spots.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: High dose rate brachytherapy (HDR BT) is a common treatment modality for cancer. In HDR BT, a radioactive source is placed inside or close to a tumor, aiming to give a high enough dose to the tumor, while sparing nearby healthy tissue and organs at risk. Treatment planning of HDR BT for prostate cancer consists of two types of decisions, placement of catheters, modeled with binary variables, and dwell times, modeled with continuous non-negative variables. Optimal spatial placement of catheters is important for avoiding local recurrence and complications, but such characteristics have not been modeled for the combined treatment planning problem of catheter placement and dwell time optimization.
Method: We propose a data-driven approach using linear regression, mutual information, and random forests to find convex estimates of spatial dose characteristics that correlate well with contiguous volumes receiving a too-high (hot spots) or too-low dose (cold spots). These estimates were incorporated in retrospective treatment plan optimization of 28 prostate cancer patients.
Results: The proposed hot-spot terms reduced the volume receiving twice the prescribed dose by 29% at 14 catheters. Also, the results illustrate the trade-offs between the number of catheters and spatial dose characteristics.
Conclusions: Our study demonstrates that incorporating a term for hot spots in the objective function of the treatment planning model is more effective in reducing hot spots than catheter placements that are not optimized for hot spots.
Method: We propose a data-driven approach using linear regression, mutual information, and random forests to find convex estimates of spatial dose characteristics that correlate well with contiguous volumes receiving a too-high (hot spots) or too-low dose (cold spots). These estimates were incorporated in retrospective treatment plan optimization of 28 prostate cancer patients.
Results: The proposed hot-spot terms reduced the volume receiving twice the prescribed dose by 29% at 14 catheters. Also, the results illustrate the trade-offs between the number of catheters and spatial dose characteristics.
Conclusions: Our study demonstrates that incorporating a term for hot spots in the objective function of the treatment planning model is more effective in reducing hot spots than catheter placements that are not optimized for hot spots.
Thibodeau-Antonacci, Alana; Popovic, Marija; Ates, Ozgur; Hua, Chia-Ho; Schneider, James; Skamene, Sonia; Freeman, Carolyn; Enger, Shirin Abbasinejad; Tsui, James Man Git
In: Medical Physics, vol. 52, iss. 6, pp. 3541–3556, 2025, ISSN: 2473-4209.
@article{nokey,
title = {Trade-off of different deep learning-based auto-segmentation approaches for treatment planning of pediatric craniospinal irradiation autocontouring of OARs for pediatric CSI},
author = {Alana Thibodeau-Antonacci and Marija Popovic and Ozgur Ates and Chia-Ho Hua and James Schneider and Sonia Skamene and Carolyn Freeman and Shirin Abbasinejad Enger and James Man Git Tsui},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17782},
doi = {10.1002/mp.17782},
issn = {2473-4209},
year = {2025},
date = {2025-04-01},
journal = {Medical Physics},
volume = {52},
issue = {6},
pages = {3541–3556},
abstract = {Background: As auto-segmentation tools become integral to radiotherapy, more commercial products emerge. However, they may not always suit our needs. One notable example is the use of adult-trained commercial software for the contouring of organs at risk (OARs) of pediatric patients.
Purpose: This study aimed to compare three auto-segmentation approaches in the context of pediatric craniospinal irradiation (CSI): commercial, out-of-the-box, and in-house.
Methods: CT scans from 142 pediatric patients undergoing CSI were obtained from St. Jude Children's Research Hospital (training: 115; validation: 27). A test dataset comprising 16 CT scans was collected from the McGill University Health Centre. All images underwent manual delineation of 18 OARs. LimbusAI v1.7 served as the commercial product, while nnU-Net was trained for benchmarking. Additionally, a two-step in-house approach was pursued where smaller 3D CT scans containing the OAR of interest were first recovered and then used as input to train organ-specific models. Three variants of the U-Net architecture were explored: a basic U-Net, an attention U-Net, and a 2.5D U-Net. The dice similarity coefficient (DSC) assessed segmentation accuracy, and the DSC trend with age was investigated (Mann-Kendall test). A radiation oncologist determined the clinical acceptability of all contours using a five-point Likert scale.
Results: Differences in the contours between the validation and test datasets reflected the distinct institutional standards. The lungs and left kidney displayed an increasing age-related trend of the DSC values with LimbusAI on the validation and test datasets. LimbusAI contours of the esophagus were often truncated distally and mistaken for the trachea for younger patients, resulting in a DSC score of less than 0.5 on both datasets. Additionally, the kidneys frequently exhibited false negatives, leading to mean DSC values that were up to 0.11 lower on the validation set and 0.07 on the test set compared to the other models. Overall, nnU-Net achieved good performance for body organs but exhibited difficulty differentiating the laterality of head structures, resulting in a large variation of DSC values with the standard deviation reaching 0.35 for the lenses. All in-house models generally had similar DSC values when compared against each other and nnU-Net. Inference time on the test data was between 47-55 min on a Central Processing Unit (CPU) for the in-house models, while it was 1h 21m with a V100 Graphics Processing Unit (GPU) for nnU-Net.
Conclusions: LimbusAI could not adapt well to pediatric anatomy for the esophagus and the kidneys. When commercial products do not suit the study population, the nnU-Net is a viable option but requires adjustments. In resource-constrained settings, the in-house model provides an alternative. Implementing an automated segmentation tool requires careful monitoring and quality assurance regardless of the approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: As auto-segmentation tools become integral to radiotherapy, more commercial products emerge. However, they may not always suit our needs. One notable example is the use of adult-trained commercial software for the contouring of organs at risk (OARs) of pediatric patients.
Purpose: This study aimed to compare three auto-segmentation approaches in the context of pediatric craniospinal irradiation (CSI): commercial, out-of-the-box, and in-house.
Methods: CT scans from 142 pediatric patients undergoing CSI were obtained from St. Jude Children's Research Hospital (training: 115; validation: 27). A test dataset comprising 16 CT scans was collected from the McGill University Health Centre. All images underwent manual delineation of 18 OARs. LimbusAI v1.7 served as the commercial product, while nnU-Net was trained for benchmarking. Additionally, a two-step in-house approach was pursued where smaller 3D CT scans containing the OAR of interest were first recovered and then used as input to train organ-specific models. Three variants of the U-Net architecture were explored: a basic U-Net, an attention U-Net, and a 2.5D U-Net. The dice similarity coefficient (DSC) assessed segmentation accuracy, and the DSC trend with age was investigated (Mann-Kendall test). A radiation oncologist determined the clinical acceptability of all contours using a five-point Likert scale.
Results: Differences in the contours between the validation and test datasets reflected the distinct institutional standards. The lungs and left kidney displayed an increasing age-related trend of the DSC values with LimbusAI on the validation and test datasets. LimbusAI contours of the esophagus were often truncated distally and mistaken for the trachea for younger patients, resulting in a DSC score of less than 0.5 on both datasets. Additionally, the kidneys frequently exhibited false negatives, leading to mean DSC values that were up to 0.11 lower on the validation set and 0.07 on the test set compared to the other models. Overall, nnU-Net achieved good performance for body organs but exhibited difficulty differentiating the laterality of head structures, resulting in a large variation of DSC values with the standard deviation reaching 0.35 for the lenses. All in-house models generally had similar DSC values when compared against each other and nnU-Net. Inference time on the test data was between 47-55 min on a Central Processing Unit (CPU) for the in-house models, while it was 1h 21m with a V100 Graphics Processing Unit (GPU) for nnU-Net.
Conclusions: LimbusAI could not adapt well to pediatric anatomy for the esophagus and the kidneys. When commercial products do not suit the study population, the nnU-Net is a viable option but requires adjustments. In resource-constrained settings, the in-house model provides an alternative. Implementing an automated segmentation tool requires careful monitoring and quality assurance regardless of the approach.
Purpose: This study aimed to compare three auto-segmentation approaches in the context of pediatric craniospinal irradiation (CSI): commercial, out-of-the-box, and in-house.
Methods: CT scans from 142 pediatric patients undergoing CSI were obtained from St. Jude Children's Research Hospital (training: 115; validation: 27). A test dataset comprising 16 CT scans was collected from the McGill University Health Centre. All images underwent manual delineation of 18 OARs. LimbusAI v1.7 served as the commercial product, while nnU-Net was trained for benchmarking. Additionally, a two-step in-house approach was pursued where smaller 3D CT scans containing the OAR of interest were first recovered and then used as input to train organ-specific models. Three variants of the U-Net architecture were explored: a basic U-Net, an attention U-Net, and a 2.5D U-Net. The dice similarity coefficient (DSC) assessed segmentation accuracy, and the DSC trend with age was investigated (Mann-Kendall test). A radiation oncologist determined the clinical acceptability of all contours using a five-point Likert scale.
Results: Differences in the contours between the validation and test datasets reflected the distinct institutional standards. The lungs and left kidney displayed an increasing age-related trend of the DSC values with LimbusAI on the validation and test datasets. LimbusAI contours of the esophagus were often truncated distally and mistaken for the trachea for younger patients, resulting in a DSC score of less than 0.5 on both datasets. Additionally, the kidneys frequently exhibited false negatives, leading to mean DSC values that were up to 0.11 lower on the validation set and 0.07 on the test set compared to the other models. Overall, nnU-Net achieved good performance for body organs but exhibited difficulty differentiating the laterality of head structures, resulting in a large variation of DSC values with the standard deviation reaching 0.35 for the lenses. All in-house models generally had similar DSC values when compared against each other and nnU-Net. Inference time on the test data was between 47-55 min on a Central Processing Unit (CPU) for the in-house models, while it was 1h 21m with a V100 Graphics Processing Unit (GPU) for nnU-Net.
Conclusions: LimbusAI could not adapt well to pediatric anatomy for the esophagus and the kidneys. When commercial products do not suit the study population, the nnU-Net is a viable option but requires adjustments. In resource-constrained settings, the in-house model provides an alternative. Implementing an automated segmentation tool requires careful monitoring and quality assurance regardless of the approach.
Morén, Björn; Thibodeau-Antonacci, Alana; Kalinowski, Jonathan; Enger, Shirin A.
Dosimetric impact of positional uncertainties and a robust optimization approach for rectal intensity-modulated brachytherapy Journal Article
In: Medical Physics, vol. 52, iss. 6, pp. 3528–3540, 2025, ISSN: 0094-2405.
@article{nokey,
title = {Dosimetric impact of positional uncertainties and a robust optimization approach for rectal intensity-modulated brachytherapy},
author = {Björn Morén and Alana Thibodeau-Antonacci and Jonathan Kalinowski and Shirin A. Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17800},
doi = {10.1002/mp.17800},
issn = {0094-2405},
year = {2025},
date = {2025-03-31},
journal = {Medical Physics},
volume = {52},
issue = {6},
pages = {3528–3540},
abstract = {Background: Intensity-modulated brachytherapy (IMBT) employs rotating high-Z shields during treatment to decrease radiation in certain directions and conform the dose distribution to the target volume. Prototypes for dynamic IMBT have been proposed for prostate, cervical, and rectal cancer.
Purpose: We considered two shielded applicators for IMBT rectal cancer treatment and investigated how rotational uncertainties in the shield angle and translational uncertainties in the source position affect plan evaluation criteria.
Methods: The effect of rotational errors of 3∘ , 5∘ and 10∘ , and translational errors of 1, 2 and 3 mm on evaluation criteria were investigated for shields with
180
∘
and
90
∘
emission windows. Further, a robust optimization approach based on quadratic penalties that includes scenarios with errors was proposed. The extent to which dosimetric effects of positional errors can be mitigated with this model was evaluated compared to a quadratic penalty model without scenarios with errors. A retrospective rectal cancer data set of ten patients was included in this study. Treatment planning was performed using the Monte Carlo-based treatment planning system, RapidBrachyMCTPS.
Results: For the largest investigated rotational error of
±
10
∘
, the clinical target volume
D
90
remained, on average, within
5
%
of the result without error, while the contralateral healthy rectal wall experienced an increase in the mean
D
0.1
c
c
,
D
2
c
c
, and
D
50
of
26
%
,
9
%
, and
1
%
for the
180
∘
shield and of 32%, 9%, and 2% for the
90
∘
shield. For translational errors of
±
2
mm, there were increases in dosimetric indices for both the superior (sup) and inferior (inf) dose spill regions. Specifically, for the
180
∘
shield, the
D
0.1
c
c
,
D
2
c
c
, and
D
50
increased by
13
%
,
11
%
, and
10
%
, respectively, for the sup region, and by
26
%
,
15
%
, and
11
%
, respectively, for the inf region. Similar results were obtained with the
90
∘
shield. Overall, the robust and traditional models had similar results. However, the number of active dwell positions obtained with the robust model was larger, and the longest dwell time was shorter.
Conclusions: We have quantified the effect of rotational shield and translational source errors of various magnitudes on evaluation criteria for rectal IMBT. The robust optimization approach was generally not able to mitigate positional errors. However, it resulted in more homogeneous dwell times, which can be beneficial in conventional high-dose-rate brachytherapy to avoid hot spots around specific dwell positions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: Intensity-modulated brachytherapy (IMBT) employs rotating high-Z shields during treatment to decrease radiation in certain directions and conform the dose distribution to the target volume. Prototypes for dynamic IMBT have been proposed for prostate, cervical, and rectal cancer.
Purpose: We considered two shielded applicators for IMBT rectal cancer treatment and investigated how rotational uncertainties in the shield angle and translational uncertainties in the source position affect plan evaluation criteria.
Methods: The effect of rotational errors of 3∘ , 5∘ and 10∘ , and translational errors of 1, 2 and 3 mm on evaluation criteria were investigated for shields with
180
∘
and
90
∘
emission windows. Further, a robust optimization approach based on quadratic penalties that includes scenarios with errors was proposed. The extent to which dosimetric effects of positional errors can be mitigated with this model was evaluated compared to a quadratic penalty model without scenarios with errors. A retrospective rectal cancer data set of ten patients was included in this study. Treatment planning was performed using the Monte Carlo-based treatment planning system, RapidBrachyMCTPS.
Results: For the largest investigated rotational error of
±
10
∘
, the clinical target volume
D
90
remained, on average, within
5
%
of the result without error, while the contralateral healthy rectal wall experienced an increase in the mean
D
0.1
c
c
,
D
2
c
c
, and
D
50
of
26
%
,
9
%
, and
1
%
for the
180
∘
shield and of 32%, 9%, and 2% for the
90
∘
shield. For translational errors of
±
2
mm, there were increases in dosimetric indices for both the superior (sup) and inferior (inf) dose spill regions. Specifically, for the
180
∘
shield, the
D
0.1
c
c
,
D
2
c
c
, and
D
50
increased by
13
%
,
11
%
, and
10
%
, respectively, for the sup region, and by
26
%
,
15
%
, and
11
%
, respectively, for the inf region. Similar results were obtained with the
90
∘
shield. Overall, the robust and traditional models had similar results. However, the number of active dwell positions obtained with the robust model was larger, and the longest dwell time was shorter.
Conclusions: We have quantified the effect of rotational shield and translational source errors of various magnitudes on evaluation criteria for rectal IMBT. The robust optimization approach was generally not able to mitigate positional errors. However, it resulted in more homogeneous dwell times, which can be beneficial in conventional high-dose-rate brachytherapy to avoid hot spots around specific dwell positions.
Purpose: We considered two shielded applicators for IMBT rectal cancer treatment and investigated how rotational uncertainties in the shield angle and translational uncertainties in the source position affect plan evaluation criteria.
Methods: The effect of rotational errors of 3∘ , 5∘ and 10∘ , and translational errors of 1, 2 and 3 mm on evaluation criteria were investigated for shields with
180
∘
and
90
∘
emission windows. Further, a robust optimization approach based on quadratic penalties that includes scenarios with errors was proposed. The extent to which dosimetric effects of positional errors can be mitigated with this model was evaluated compared to a quadratic penalty model without scenarios with errors. A retrospective rectal cancer data set of ten patients was included in this study. Treatment planning was performed using the Monte Carlo-based treatment planning system, RapidBrachyMCTPS.
Results: For the largest investigated rotational error of
±
10
∘
, the clinical target volume
D
90
remained, on average, within
5
%
of the result without error, while the contralateral healthy rectal wall experienced an increase in the mean
D
0.1
c
c
,
D
2
c
c
, and
D
50
of
26
%
,
9
%
, and
1
%
for the
180
∘
shield and of 32%, 9%, and 2% for the
90
∘
shield. For translational errors of
±
2
mm, there were increases in dosimetric indices for both the superior (sup) and inferior (inf) dose spill regions. Specifically, for the
180
∘
shield, the
D
0.1
c
c
,
D
2
c
c
, and
D
50
increased by
13
%
,
11
%
, and
10
%
, respectively, for the sup region, and by
26
%
,
15
%
, and
11
%
, respectively, for the inf region. Similar results were obtained with the
90
∘
shield. Overall, the robust and traditional models had similar results. However, the number of active dwell positions obtained with the robust model was larger, and the longest dwell time was shorter.
Conclusions: We have quantified the effect of rotational shield and translational source errors of various magnitudes on evaluation criteria for rectal IMBT. The robust optimization approach was generally not able to mitigate positional errors. However, it resulted in more homogeneous dwell times, which can be beneficial in conventional high-dose-rate brachytherapy to avoid hot spots around specific dwell positions.
2024
Rahbaran, Maryam; Kalinowski, Jonathan; DeCunha, Joseph M.; Croce, Kevin J.; Bergmark, Brian A.; Tsui, James M. G.; Devlin, Phillip M.; Enger, Shirin A.
RapidBrachyIVBT: A dosimetry software for patient-specific intravascular brachytherapy dose calculations on optical coherence tomography images Journal Article
In: Medical Physics, vol. 52, iss. 2, pp. 1256-1267, 2024, ISSN: 2473-4209.
@article{Rahbaran2025-gg,
title = {RapidBrachyIVBT: A dosimetry software for patient-specific intravascular brachytherapy dose calculations on optical coherence tomography images},
author = {Maryam Rahbaran and Jonathan Kalinowski and Joseph M. DeCunha and Kevin J. Croce and Brian A. Bergmark and James M. G. Tsui and Phillip M. Devlin and Shirin A. Enger},
doi = {https://doi.org/10.1002/mp.17462},
issn = {2473-4209},
year = {2024},
date = {2024-11-19},
journal = {Medical Physics},
volume = {52},
issue = {2},
pages = {1256-1267},
abstract = {Background
Large reported variability in the material composition and geometrical components of the Xoft electronic high dose rate brachytherapy causes inter-source discrepancy in the source output. This variability is due to the manual manufacturing and assembly of the sources.
Purpose
This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods
E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results
The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
, reaching a peak at
cm and
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
values, but at higher polar angles, they increased to 300%.
Conclusions
A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background
Large reported variability in the material composition and geometrical components of the Xoft electronic high dose rate brachytherapy causes inter-source discrepancy in the source output. This variability is due to the manual manufacturing and assembly of the sources.
Purpose
This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods
E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results
The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
, reaching a peak at
cm and
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
values, but at higher polar angles, they increased to 300%.
Conclusions
A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.
Large reported variability in the material composition and geometrical components of the Xoft electronic high dose rate brachytherapy causes inter-source discrepancy in the source output. This variability is due to the manual manufacturing and assembly of the sources.
Purpose
This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods
E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results
The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
, reaching a peak at
cm and
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
values, but at higher polar angles, they increased to 300%.
Conclusions
A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.
Esmaelbeigi, Azin; Kalinowski, Jonathan; Tomic, Nada; Rivard, Mark J.; Vuong, Te; Devic, Slobodan; Enger, Shirin A.
E-Brachy: New dosimetry package for electronic brachytherapy sources Journal Article
In: Medical Physics, vol. 52, iss. 1, pp. 662–672, 2024, ISSN: 2473-4209.
@article{Esmaelbeigi2025-ww,
title = {E-Brachy: New dosimetry package for electronic brachytherapy sources},
author = {Azin Esmaelbeigi and Jonathan Kalinowski and Nada Tomic and Mark J. Rivard and Te Vuong and Slobodan Devic and Shirin A. Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17462},
doi = {10.1002/mp.17462},
issn = {2473-4209},
year = {2024},
date = {2024-10-26},
urldate = {2024-10-26},
journal = {Medical Physics},
volume = {52},
issue = {1},
pages = {662–672},
abstract = {Background: Large reported variability in the material composition and geometrical components of the Xoft electronic high dose rate brachytherapy causes inter-source discrepancy in the source output. This variability is due to the manual manufacturing and assembly of the sources.
Purpose: This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods: E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results: The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
0.061
±
0.001
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
θ
≥
150
∘
, reaching a peak at
r
=
3
cm and
θ
=
175
∘
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
θ
values, but at higher polar angles, they increased to 300%.
Conclusions: A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.
Keywords: dosimetry; electronic brachytherapy; monte carlo simulations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: Large reported variability in the material composition and geometrical components of the Xoft electronic high dose rate brachytherapy causes inter-source discrepancy in the source output. This variability is due to the manual manufacturing and assembly of the sources.
Purpose: This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods: E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results: The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
0.061
±
0.001
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
θ
≥
150
∘
, reaching a peak at
r
=
3
cm and
θ
=
175
∘
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
θ
values, but at higher polar angles, they increased to 300%.
Conclusions: A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.
Keywords: dosimetry; electronic brachytherapy; monte carlo simulations.
Purpose: This study aimed to develop a dosimetry software tool called E-Brachy to characterize the Xoft source and quantify the discrepancies in its photon spectrum and dosimetric properties.
Methods: E-Brachy is based on the Geant4 Monte Carlo toolkit and consists of two parts. In part one, the geometry and material composition for the source received in the computer-aided design format from the vendor were converted to the geometry description markup language format using the GUIMesh Python tool and integrated into the E-Brachy software. There was a large variation in material composition and thickness for some of the tube components. The simulation started from electrons and resulted in x-ray generations in the anode region. Multithreading, a track length estimation, and the uniform bremsstrahlung splitting variance reduction techniques were used to decrease the simulation time and increase the x-ray production. The photon energy, position, and momentum were saved into a phase space file as the photon exited the source, but before interacting with the external environment. The obtained x-ray energy spectrum was compared with measurements from the National Institute of Standards and Technology (NIST). In part two, by sampling from the generated photons, the dose rates and dosimetric parameters according to the TG-43 protocol were calculated for model S7500 and compared to the ones previously calculated for model S700 source, which were deemed identical by the manufacturer.
Results: The material composition that resulted in the most similar spectrum as the measured NIST spectrum with Pearson's correlation coefficient of 0.99 and a calculated Euclidean difference of
0.061
±
0.001
keV was chosen for further dosimetric analysis of the model S7500 source. Characteristic peaks showed the presence of tungsten, yttrium, and silver in the source components. Differences in dose rates between the two source models surpassed 20% for polar angles
θ
≥
150
∘
, reaching a peak at
r
=
3
cm and
θ
=
175
∘
. The differences in the radial dose function values were within 5%. The relative difference in percentage between the anisotropy function values of the two models was closer to 0 for smaller
θ
values, but at higher polar angles, they increased to 300%.
Conclusions: A software package called E-Brachy was successfully developed for the characterization and dosimetry of Xoft electronic brachytherapy sources. E-Brachy can be combined with spectral measurements to investigate the inter- and intra-source variability. The software package was tested by comparing the simulated spectra from the S7500 Xoft source model with NIST measurements and its TG-43 parameters with the S700 model. The TG-43 parameters between the two sources significantly exceed the recommendations of TG-56.
Keywords: dosimetry; electronic brachytherapy; monte carlo simulations.
Robitaille, Maude; Ménard, Cynthia; Famulari, Gabriel; Béliveau-Nadeau, Dominic; Enger, Shirin A
169Yb-based high dose rate intensity modulated brachytherapy for focal treatment of prostate cancer Journal Article
In: 2024.
@article{nokey,
title = {169Yb-based high dose rate intensity modulated brachytherapy for focal treatment of prostate cancer},
author = {Maude Robitaille and Cynthia Ménard and Gabriel Famulari and Dominic Béliveau-Nadeau and Shirin A Enger},
doi = {10.1016/j.brachy.2024.05.005},
year = {2024},
date = {2024-07-21},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Jafarzadeh, Hossein; Antaki, Majd; Mao, Ximeng; Duclos, Marie; Maleki, Farhard; Enger, Shirin A
Penalty weight tuning in high dose rate brachytherapy using multi-objective Bayesian optimization Journal Article
In: Physics in Medicine & Biology, vol. 69, 2024.
@article{nokey,
title = {Penalty weight tuning in high dose rate brachytherapy using multi-objective Bayesian optimization},
author = {Hossein Jafarzadeh and Majd Antaki and Ximeng Mao and Marie Duclos and Farhard Maleki and Shirin A Enger },
doi = {10.1088/1361-6560/ad4448},
year = {2024},
date = {2024-05-21},
urldate = {2024-05-21},
journal = {Physics in Medicine & Biology},
volume = {69},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Berumen, Francisco; Ouellet, Samuel; Enger, Shirin; Beaulieu, Luc
Aleatoric and epistemic uncertainty extraction of patient-specific deep learning-based dose predictions in LDR prostate brachytherapy Journal Article
In: Physics in Medicine & Biology, vol. 69, no. 8, 2024.
@article{berumen2024aleatoric,
title = {Aleatoric and epistemic uncertainty extraction of patient-specific deep learning-based dose predictions in LDR prostate brachytherapy},
author = {Francisco Berumen and Samuel Ouellet and Shirin Enger and Luc Beaulieu},
doi = {10.1088/1361-6560/ad3418},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Physics in Medicine & Biology},
volume = {69},
number = {8},
publisher = {IOP Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kalinowski, Jonathan; Enger, Shirin A
RapidBrachyTG43: A Geant4-based TG-43 parameter and dose calculation module for brachytherapy dosimetry Journal Article
In: Medical Physics, vol. 51, no. 5, pp. 3746–757, 2024.
@article{kalinowski2024rapidbrachytg43,
title = {RapidBrachyTG43: A Geant4-based TG-43 parameter and dose calculation module for brachytherapy dosimetry},
author = {Jonathan Kalinowski and Shirin A Enger},
doi = {10.1002/mp.16948},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Medical Physics},
volume = {51},
number = {5},
pages = {3746–757},
publisher = {Wiley Online Library},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2023
Rahbaran, Maryam; Kalinowski, Jonathan; DeCunha, Joseph; Croce, Kevin; Bergmark, Brian; Devlin, Philip; Tsui, James; Enger, Shirin A.
Development Of a Novel Dosimetry Software for Patient-specific Intravascular Brachytherapy Treatment Planning on Optical Coherence Tomography Images Presentation
23.09.2023, (COMP-CARO 2023 Joint Scientific Meeting).
@misc{nokey,
title = {Development Of a Novel Dosimetry Software for Patient-specific Intravascular Brachytherapy Treatment Planning on Optical Coherence Tomography Images},
author = {Maryam Rahbaran and Jonathan Kalinowski and Joseph DeCunha and Kevin Croce and Brian Bergmark and Philip Devlin and James Tsui and Shirin A. Enger},
year = {2023},
date = {2023-09-23},
note = {COMP-CARO 2023 Joint Scientific Meeting},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Rahbaran, Maryam; Kalinowski, Jonathan; Tsui, James; DeCunha, Joseph; Croce, Kevin; Bergmark, Brian; Devlin, Philip; Enger, Shirin A.
Development Of a Novel Dosimetry Software for Patient-specific Intravascular Brachytherapy Treatment Planning on Optical Coherence Tomography Images Presentation
22.06.2023, (2023 American Brachytherapy Society (ABS) Annual Meeting, Vancouver, Canada).
@misc{nokey,
title = {Development Of a Novel Dosimetry Software for Patient-specific Intravascular Brachytherapy Treatment Planning on Optical Coherence Tomography Images},
author = {Maryam Rahbaran and Jonathan Kalinowski and James Tsui and Joseph DeCunha and Kevin Croce and Brian Bergmark and Philip Devlin and Shirin A. Enger},
year = {2023},
date = {2023-06-22},
urldate = {2023-06-22},
note = {2023 American Brachytherapy Society (ABS) Annual Meeting, Vancouver, Canada},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Berumen, Francisco; Enger, Shirin A.; Beaulieu, Luc
Fast DM,M calculation in LDR brachytherapy using deep learning methods Journal Article
In: Physics in Medicine & Biology, 2023.
@article{nokey_29,
title = {Fast DM,M calculation in LDR brachytherapy using deep learning methods},
author = {Francisco Berumen and Shirin A. Enger and Luc Beaulieu},
doi = {10.1088/1361-6560/accd42},
year = {2023},
date = {2023-05-23},
urldate = {2023-05-23},
journal = {Physics in Medicine & Biology},
abstract = {Objective.The Monte Carlo (MC) method provides a complete solution to the tissue heterogeneity effects in low-energy low-dose rate (LDR) brachytherapy. However, long computation times limit the clinical implementation of MC-based treatment planning solutions. This work aims to apply deep learning (DL) methods, specifically a model trained with MC simulations, to predict accurate dose to medium in medium (DM,M) distributions in LDR prostate brachytherapy.Approach.To train the DL model, 2369 single-seed configurations, corresponding to 44 prostate patient plans, were used. These patients underwent LDR brachytherapy treatments in which125I SelectSeed sources were implanted. For each seed configuration, the patient geometry, the MC dose volume and the single-seed plan volume were used to train a 3D Unet convolutional neural network. Previous knowledge was included in the network as anr2kernel related to the first-order dose dependency in brachytherapy. MC and DL dose distributions were compared through the dose maps, isodose lines, and dose-volume histograms. Features enclosed in the model were visualized.Main results.Model features started from the symmetrical kernel and finalized with an anisotropic representation that considered the patient organs and their interfaces, the source position, and the low- and high-dose regions. For a full prostate patient, small differences were seen below the 20% isodose line. When comparing DL-based and MC-based calculations, the predicted CTVD90metric had an average difference of -0.1%. Average differences for OARs were -1.3%, 0.07%, and 4.9% for the rectumD2cc, the bladderD2cc, and the urethraD0.1cc. The model took 1.8 ms to predict a complete 3DDM,Mvolume (1.18 M voxels).Significance.The proposed DL model stands for a simple and fast engine which includes prior physics knowledge of the problem. Such an engine considers the anisotropy of a brachytherapy source and the patient tissue composition.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective.The Monte Carlo (MC) method provides a complete solution to the tissue heterogeneity effects in low-energy low-dose rate (LDR) brachytherapy. However, long computation times limit the clinical implementation of MC-based treatment planning solutions. This work aims to apply deep learning (DL) methods, specifically a model trained with MC simulations, to predict accurate dose to medium in medium (DM,M) distributions in LDR prostate brachytherapy.Approach.To train the DL model, 2369 single-seed configurations, corresponding to 44 prostate patient plans, were used. These patients underwent LDR brachytherapy treatments in which125I SelectSeed sources were implanted. For each seed configuration, the patient geometry, the MC dose volume and the single-seed plan volume were used to train a 3D Unet convolutional neural network. Previous knowledge was included in the network as anr2kernel related to the first-order dose dependency in brachytherapy. MC and DL dose distributions were compared through the dose maps, isodose lines, and dose-volume histograms. Features enclosed in the model were visualized.Main results.Model features started from the symmetrical kernel and finalized with an anisotropic representation that considered the patient organs and their interfaces, the source position, and the low- and high-dose regions. For a full prostate patient, small differences were seen below the 20% isodose line. When comparing DL-based and MC-based calculations, the predicted CTVD90metric had an average difference of -0.1%. Average differences for OARs were -1.3%, 0.07%, and 4.9% for the rectumD2cc, the bladderD2cc, and the urethraD0.1cc. The model took 1.8 ms to predict a complete 3DDM,Mvolume (1.18 M voxels).Significance.The proposed DL model stands for a simple and fast engine which includes prior physics knowledge of the problem. Such an engine considers the anisotropy of a brachytherapy source and the patient tissue composition.
Jafarzadeh, Hossein
Doctoral Internship Award Miscellaneous
2023, (Graduate and Post Doctoral Studies, McGill University ).
@misc{nokey,
title = {Doctoral Internship Award},
author = {Hossein Jafarzadeh},
year = {2023},
date = {2023-05-20},
urldate = {2023-05-20},
note = {Graduate and Post Doctoral Studies, McGill University
},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Antaki, Majd; Renaud, Marc-André; Morcos, Marc; Seuntjens, Jan; Enger, Shirin A.
Applying the column generation method to the intensity modulated high dose rate brachytherapy inverse planning problem Journal Article
In: Physics in Medicine & Biology, 2023.
@article{nokey_28,
title = {Applying the column generation method to the intensity modulated high dose rate brachytherapy inverse planning problem},
author = {Majd Antaki and Marc-André Renaud and Marc Morcos and Jan Seuntjens and Shirin A. Enger },
doi = {10.1088/1361-6560/acbc63},
year = {2023},
date = {2023-03-13},
urldate = {2023-03-13},
journal = {Physics in Medicine & Biology},
abstract = {Objective.Intensity modulated high dose rate brachytherapy (IMBT) is a rapidly developing application of brachytherapy where anisotropic dose distributions can be produced at each source dwell position. This technique is made possible by placing rotating metallic shields inside brachytherapy needles or catheters. By dynamically directing the radiation towards the tumours and away from the healthy tissues, a more conformal dose distribution can be obtained. The resulting treatment planning involves optimizing dwell position and shield angle (DPSA). The aim of this study was to investigate the column generation method for IMBT treatment plan optimization.Approach.A column generation optimization algorithm was developed to optimize the dwell times and shield angles. A retrospective study was performed on 10 prostate cases using RapidBrachyMCTPS. At every iteration, the plan was optimized with the chosen DPSA which would best improve the cost function that was added to the plan. The optimization process was stopped when the remaining DPSAs would not add value to the plan to limit the plan complexity.Main results.The average number of DPSAs and voxels were 2270 and 7997, respectively. The column generation approach yielded near-optimal treatment plans by using only 11% of available DPSAs on average in ten prostate cases. The coverage and organs at risk constraints passed in all ten cases.Significance.The column generation method produced high-quality deliverable prostate IMBT plans. The treatment plan quality reached a plateau, where adding more DPSAs had a minimal effect on dose volume histogram parameters. The iterative nature of the column generation method allows early termination of the treatment plan creation process as soon as the dosimetric indices from dose volume histogram satisfy the clinical requirements or if their values stabilize.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective.Intensity modulated high dose rate brachytherapy (IMBT) is a rapidly developing application of brachytherapy where anisotropic dose distributions can be produced at each source dwell position. This technique is made possible by placing rotating metallic shields inside brachytherapy needles or catheters. By dynamically directing the radiation towards the tumours and away from the healthy tissues, a more conformal dose distribution can be obtained. The resulting treatment planning involves optimizing dwell position and shield angle (DPSA). The aim of this study was to investigate the column generation method for IMBT treatment plan optimization.Approach.A column generation optimization algorithm was developed to optimize the dwell times and shield angles. A retrospective study was performed on 10 prostate cases using RapidBrachyMCTPS. At every iteration, the plan was optimized with the chosen DPSA which would best improve the cost function that was added to the plan. The optimization process was stopped when the remaining DPSAs would not add value to the plan to limit the plan complexity.Main results.The average number of DPSAs and voxels were 2270 and 7997, respectively. The column generation approach yielded near-optimal treatment plans by using only 11% of available DPSAs on average in ten prostate cases. The coverage and organs at risk constraints passed in all ten cases.Significance.The column generation method produced high-quality deliverable prostate IMBT plans. The treatment plan quality reached a plateau, where adding more DPSAs had a minimal effect on dose volume histogram parameters. The iterative nature of the column generation method allows early termination of the treatment plan creation process as soon as the dosimetric indices from dose volume histogram satisfy the clinical requirements or if their values stabilize.
2022
Morén, Björn; Antaki, Majd; Famulari, Gabriel; Morcos, Marc; Larsson, Torbjörn; Enger, Shirin A; Tedgren, Åsa Carlsson
In: Medical Physics, 2022.
@article{nokey_30,
title = {Dosimetric impact of a robust optimization approach to mitigate effects from rotational uncertainty in prostate intensity-modulated brachytherapy},
author = {Björn Morén and Majd Antaki and Gabriel Famulari and Marc Morcos and Torbjörn Larsson and Shirin A Enger and Åsa Carlsson Tedgren},
doi = {10.1002/mp.16134},
year = {2022},
date = {2022-12-22},
journal = {Medical Physics},
abstract = {Background: Intensity-modulated brachytherapy (IMBT) is an emerging technology for cancer treatment, in which radiation sources are shielded to shape the dose distribution. The rotatable shields provide an additional degree of freedom, but also introduce an additional, directional, type of uncertainty, compared to conventional high-dose-rate brachytherapy (HDR BT).
Purpose: We propose and evaluate a robust optimization approach to mitigate the effects of rotational uncertainty in the shields with respect to planning criteria.
Methods: A previously suggested prototype for platinum-shielded prostate 169 Yb-based dynamic IMBT is considered. We study a retrospective patient data set (anatomical contours and catheter placement) from two clinics, consisting of six patients that had previously undergone conventional 192 Ir HDR BT treatment. The Monte Carlo-based treatment planning software RapidBrachyMCTPS is used for dose calculations. In our computational experiments, we investigate systematic rotational shield errors of ±10° and ±20°, and the same systematic error is applied to all dwell positions in each scenario. This gives us three scenarios, one nominal and two with errors. The robust optimization approach finds a compromise between the average and worst-case scenario outcomes.
Results: We compare dose plans obtained from standard models and their robust counterparts. With dwell times obtained from a linear penalty model (LPM), for 10° errors, the dose to urethra (D0.1cc) and rectum (D0.1cc and D1cc) increase with up to 5% and 7%, respectively, in the worst-case scenario, while with the robust counterpart, the corresponding increases were 3% and 3%. For all patients and all evaluated criteria, the worst-case scenario outcome with the robust approach had lower deviation compared to the standard model, without compromising target coverage. We also evaluated shield errors up to 20° and while the deviations increased to a large extent with the standard models, the robust models were capable of handling even such large errors.
Conclusions: We conclude that robust optimization can be used to mitigate the effects from rotational uncertainty and to ensure the treatment plan quality of IMBT.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: Intensity-modulated brachytherapy (IMBT) is an emerging technology for cancer treatment, in which radiation sources are shielded to shape the dose distribution. The rotatable shields provide an additional degree of freedom, but also introduce an additional, directional, type of uncertainty, compared to conventional high-dose-rate brachytherapy (HDR BT).
Purpose: We propose and evaluate a robust optimization approach to mitigate the effects of rotational uncertainty in the shields with respect to planning criteria.
Methods: A previously suggested prototype for platinum-shielded prostate 169 Yb-based dynamic IMBT is considered. We study a retrospective patient data set (anatomical contours and catheter placement) from two clinics, consisting of six patients that had previously undergone conventional 192 Ir HDR BT treatment. The Monte Carlo-based treatment planning software RapidBrachyMCTPS is used for dose calculations. In our computational experiments, we investigate systematic rotational shield errors of ±10° and ±20°, and the same systematic error is applied to all dwell positions in each scenario. This gives us three scenarios, one nominal and two with errors. The robust optimization approach finds a compromise between the average and worst-case scenario outcomes.
Results: We compare dose plans obtained from standard models and their robust counterparts. With dwell times obtained from a linear penalty model (LPM), for 10° errors, the dose to urethra (D0.1cc) and rectum (D0.1cc and D1cc) increase with up to 5% and 7%, respectively, in the worst-case scenario, while with the robust counterpart, the corresponding increases were 3% and 3%. For all patients and all evaluated criteria, the worst-case scenario outcome with the robust approach had lower deviation compared to the standard model, without compromising target coverage. We also evaluated shield errors up to 20° and while the deviations increased to a large extent with the standard models, the robust models were capable of handling even such large errors.
Conclusions: We conclude that robust optimization can be used to mitigate the effects from rotational uncertainty and to ensure the treatment plan quality of IMBT.
Purpose: We propose and evaluate a robust optimization approach to mitigate the effects of rotational uncertainty in the shields with respect to planning criteria.
Methods: A previously suggested prototype for platinum-shielded prostate 169 Yb-based dynamic IMBT is considered. We study a retrospective patient data set (anatomical contours and catheter placement) from two clinics, consisting of six patients that had previously undergone conventional 192 Ir HDR BT treatment. The Monte Carlo-based treatment planning software RapidBrachyMCTPS is used for dose calculations. In our computational experiments, we investigate systematic rotational shield errors of ±10° and ±20°, and the same systematic error is applied to all dwell positions in each scenario. This gives us three scenarios, one nominal and two with errors. The robust optimization approach finds a compromise between the average and worst-case scenario outcomes.
Results: We compare dose plans obtained from standard models and their robust counterparts. With dwell times obtained from a linear penalty model (LPM), for 10° errors, the dose to urethra (D0.1cc) and rectum (D0.1cc and D1cc) increase with up to 5% and 7%, respectively, in the worst-case scenario, while with the robust counterpart, the corresponding increases were 3% and 3%. For all patients and all evaluated criteria, the worst-case scenario outcome with the robust approach had lower deviation compared to the standard model, without compromising target coverage. We also evaluated shield errors up to 20° and while the deviations increased to a large extent with the standard models, the robust models were capable of handling even such large errors.
Conclusions: We conclude that robust optimization can be used to mitigate the effects from rotational uncertainty and to ensure the treatment plan quality of IMBT.
Kalinowski, Jonathan
McGill Faculty of Medicine and Health Sciences Internal Studentship award
2022.
@award{nokey,
title = {McGill Faculty of Medicine and Health Sciences Internal Studentship},
author = {Jonathan Kalinowski},
url = {https://www.mcgill.ca/medhealthsci-gradstudies/funding-opportunities/graduate-students/internal-studentships},
year = {2022},
date = {2022-08-15},
urldate = {2022-08-15},
organization = {McGill University Faculty of Medicine and Health Sciences},
abstract = {Internal Studentships are open to highly qualified Faculty of Medicine graduate students who are registered full-time in a research training program (Thesis) leading to an M.Sc or PhD degree.
},
keywords = {},
pubstate = {published},
tppubtype = {award}
}
Internal Studentships are open to highly qualified Faculty of Medicine graduate students who are registered full-time in a research training program (Thesis) leading to an M.Sc or PhD degree.
Rahbaran, Maryam
Graduate Excellence Award award
2022.
@award{nokey,
title = {Graduate Excellence Award },
author = {Maryam Rahbaran},
year = {2022},
date = {2022-08-08},
abstract = {Merit-based recruitment award for first year MSc students. },
keywords = {},
pubstate = {published},
tppubtype = {award}
}
Merit-based recruitment award for first year MSc students.
Jafarzadeh, Hossein
Biological & Biomedical Engineering PhD Recruitment Award award
2022.
@award{nokey,
title = {Biological & Biomedical Engineering PhD Recruitment Award },
author = {Hossein Jafarzadeh },
url = {https://www.mcgill.ca/bbme/programs/funding#BME-Recruitment-Award},
year = {2022},
date = {2022-05-10},
keywords = {},
pubstate = {published},
tppubtype = {award}
}
Enger, Shirin A.; Famulari, Gabriel
Delivery system for intensity modulated high dose rate brachytherapy with intermediate energy brachytherapy isotopes Patent
2022, (US Patent 11,324,966).
@patent{enger2022delivery,
title = {Delivery system for intensity modulated high dose rate brachytherapy with intermediate energy brachytherapy isotopes},
author = {Shirin A. Enger and Gabriel Famulari},
year = {2022},
date = {2022-05-01},
urldate = {2022-05-01},
publisher = {Google Patents},
note = {US Patent 11,324,966},
keywords = {},
pubstate = {published},
tppubtype = {patent}
}
Rahbaran, Maryam; Kalinowski, Jonathan; Tsui, James; DeCunha, Joseph; Enger, Shirin A.
Monte-Carlo Based Simulations of the Uncertainties in Clinical Water-Based Intravascular Brachytherapy Dosimetry Presentation
11.04.2022.
@misc{nokey,
title = {Monte-Carlo Based Simulations of the Uncertainties in Clinical Water-Based Intravascular Brachytherapy Dosimetry},
author = {Maryam Rahbaran and Jonathan Kalinowski and James Tsui and Joseph DeCunha and Shirin A. Enger},
year = {2022},
date = {2022-04-11},
urldate = {2022-04-11},
journal = {MCMA},
abstract = {"Introduction
Coronary artery disease (CAD) is the most common form of cardiovascular disease and is caused by excess plaque along the arterial wall, blocking blood flow to the heart (stenosis). Percutaneous transluminal coronary angioplasty widens a narrowed artery, leaving behind metal stents (1). However, in-stent restenosis (ISR) may occur due to damage to the arterial wall tissue, triggering neointimal hyperplasia which produces fibrotic and calcified plaques, narrowing the artery again. Drug-eluting stents (DES) slowly release medication to inhibit neointimal hyperplasia to prevent ISR but they fail in 3% to 20% of cases (2). Intravascular brachytherapy (IVBT), which uses b-emitting radionuclides to prevent ISR, is used in these failed cases. However, current dosimetry for IVBT is water based and does not consider attenuation of the radiation by heterogeneities such as the IVBT device guidewire, non-uniform distribution of calcified plaques, and stent material, or the angular dependence of dose distribution (3, 4, 5). The aim of this study was to investigate the uncertainties in clinical water based IVBT dosimetry, considering the effect of heterogeneities on dose distribution.
Materials & Methods
An inhouse Monte-Carlo based dosimetry package for IVBT applications based on Geant4 10.04 (patch 2) was developed. Patient’s artery was modelled as a 32 mm long, 8.4 mm diameter cylinder comprised of three layers: tunica media, represented with muscle, tunica intima, represented with fibrotic plaque, and tunica adventitia, represented with collagen. These layers had mass densities 1.06 g/cm3, 1.22 g/cm3 and 1.07 g/cm3 respectively. The innermost layer consisted of calcified plaque of density 1.45 g/cm3 with varying thicknesses between 0.9 and 1.9 mm with an eccentric shape and a rough surface. The stents had similar composition to Boston Scientific Synergy stents and were modelled to not overlap. The Novoste Beta-Cath 3.5F IVBT device model was used, which has a 90Sr90Y source. The geometry is shown in Figure 1a. A cylindrical scoring geometry was implemented. Two set of simulations were performed. In the first simulation called water phantom, the entire system consisted of water with unit density, and dose to water was calculated similar to the clinical water based dosimetry. In the second simulation called the artery model proper material and mass densities were assigned to each component. To ensure uncertainties below 0.8% within a 1 mm radial distance to the source and 2% within 4.2 mm from the source, 100 million decay events were simulated. The Penelope physics list was used to simulate the electromagnetic interactions between particles. Average, minimum, and maximum dose was calculated at 2.0 mm from the source center and directly and 1 mm behind the outermost stents and guidewire. Absorbed dose was normalized to 23 Gy at 2.0 mm from the source center.
Results
International Conference on Monte Carlo Techniques for Medical Applications, 2022
Compared to the water phantom (Figure 1b), average dose in the artery model (Figure 1c) was attenuated by 50.9% at 2 mm from the source centre and directly behind the guidewire and outermost stent by 66.2%, and by 69.5% 1 mm behind this region. There was significant variation in dose around the source due to the guidewire attenuating dose the most, and heterogeneous distribution of calcification.
Discussion & Conclusions
Dosimetry for IVBT based on dose rate in water is not accurate. Heterogeneities need to be considered to deliver adequate dose to the lesion area. Stent material, heterogenous distribution of calcification and the off cantered placement of the guidewire affects the uniformity of dose distribution around the source. Patients may benefit from personalized treatment planning taking dose-attenuating by different tissue/material heterogeneities into account.
References
[1] Virani, Salim, S., et al. ""Heart Disease and Stroke Statistics—2020 Update"". Circulation, vol. 141, no. 9, March 03, 2020, pp. e336. doi: 10.1161/CIR.0000000000000757.
[2] Lee M, Banka G. In-stent restenosis. Interv Cardiol Clin 2016;5: 211e220.
[3] Chiu-Tsao ST, Schaart DR, Soares CG, et al. Dose calculation formalisms and consensus dosimetry parameters for intravascular brachytherapy dosimetry: Recommendations of the AAPM Therapy Physics Committee Task Group No. 149. Med Phys 2007;34: 4126e4157.
[4] Rivard MJ, Coursey BM, DeWerd LA, et al. Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations. Med Phys 2004;31:633e674.
[5] Nath R, Amols H, Coffey C, et al. Intravascular brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task group No. 60. Med Phys 1999;26:119e152.’
[6] Agostinelli S, Allison J, Amako K, et al. Geant4da simulation toolkit. Nucl Instrum Methods Phys Res 2003;506:230e303."},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
"Introduction
Coronary artery disease (CAD) is the most common form of cardiovascular disease and is caused by excess plaque along the arterial wall, blocking blood flow to the heart (stenosis). Percutaneous transluminal coronary angioplasty widens a narrowed artery, leaving behind metal stents (1). However, in-stent restenosis (ISR) may occur due to damage to the arterial wall tissue, triggering neointimal hyperplasia which produces fibrotic and calcified plaques, narrowing the artery again. Drug-eluting stents (DES) slowly release medication to inhibit neointimal hyperplasia to prevent ISR but they fail in 3% to 20% of cases (2). Intravascular brachytherapy (IVBT), which uses b-emitting radionuclides to prevent ISR, is used in these failed cases. However, current dosimetry for IVBT is water based and does not consider attenuation of the radiation by heterogeneities such as the IVBT device guidewire, non-uniform distribution of calcified plaques, and stent material, or the angular dependence of dose distribution (3, 4, 5). The aim of this study was to investigate the uncertainties in clinical water based IVBT dosimetry, considering the effect of heterogeneities on dose distribution.
Materials & Methods
An inhouse Monte-Carlo based dosimetry package for IVBT applications based on Geant4 10.04 (patch 2) was developed. Patient’s artery was modelled as a 32 mm long, 8.4 mm diameter cylinder comprised of three layers: tunica media, represented with muscle, tunica intima, represented with fibrotic plaque, and tunica adventitia, represented with collagen. These layers had mass densities 1.06 g/cm3, 1.22 g/cm3 and 1.07 g/cm3 respectively. The innermost layer consisted of calcified plaque of density 1.45 g/cm3 with varying thicknesses between 0.9 and 1.9 mm with an eccentric shape and a rough surface. The stents had similar composition to Boston Scientific Synergy stents and were modelled to not overlap. The Novoste Beta-Cath 3.5F IVBT device model was used, which has a 90Sr90Y source. The geometry is shown in Figure 1a. A cylindrical scoring geometry was implemented. Two set of simulations were performed. In the first simulation called water phantom, the entire system consisted of water with unit density, and dose to water was calculated similar to the clinical water based dosimetry. In the second simulation called the artery model proper material and mass densities were assigned to each component. To ensure uncertainties below 0.8% within a 1 mm radial distance to the source and 2% within 4.2 mm from the source, 100 million decay events were simulated. The Penelope physics list was used to simulate the electromagnetic interactions between particles. Average, minimum, and maximum dose was calculated at 2.0 mm from the source center and directly and 1 mm behind the outermost stents and guidewire. Absorbed dose was normalized to 23 Gy at 2.0 mm from the source center.
Results
International Conference on Monte Carlo Techniques for Medical Applications, 2022
Compared to the water phantom (Figure 1b), average dose in the artery model (Figure 1c) was attenuated by 50.9% at 2 mm from the source centre and directly behind the guidewire and outermost stent by 66.2%, and by 69.5% 1 mm behind this region. There was significant variation in dose around the source due to the guidewire attenuating dose the most, and heterogeneous distribution of calcification.
Discussion & Conclusions
Dosimetry for IVBT based on dose rate in water is not accurate. Heterogeneities need to be considered to deliver adequate dose to the lesion area. Stent material, heterogenous distribution of calcification and the off cantered placement of the guidewire affects the uniformity of dose distribution around the source. Patients may benefit from personalized treatment planning taking dose-attenuating by different tissue/material heterogeneities into account.
References
[1] Virani, Salim, S., et al. ""Heart Disease and Stroke Statistics—2020 Update"". Circulation, vol. 141, no. 9, March 03, 2020, pp. e336. doi: 10.1161/CIR.0000000000000757.
[2] Lee M, Banka G. In-stent restenosis. Interv Cardiol Clin 2016;5: 211e220.
[3] Chiu-Tsao ST, Schaart DR, Soares CG, et al. Dose calculation formalisms and consensus dosimetry parameters for intravascular brachytherapy dosimetry: Recommendations of the AAPM Therapy Physics Committee Task Group No. 149. Med Phys 2007;34: 4126e4157.
[4] Rivard MJ, Coursey BM, DeWerd LA, et al. Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations. Med Phys 2004;31:633e674.
[5] Nath R, Amols H, Coffey C, et al. Intravascular brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task group No. 60. Med Phys 1999;26:119e152.’
[6] Agostinelli S, Allison J, Amako K, et al. Geant4da simulation toolkit. Nucl Instrum Methods Phys Res 2003;506:230e303."
Coronary artery disease (CAD) is the most common form of cardiovascular disease and is caused by excess plaque along the arterial wall, blocking blood flow to the heart (stenosis). Percutaneous transluminal coronary angioplasty widens a narrowed artery, leaving behind metal stents (1). However, in-stent restenosis (ISR) may occur due to damage to the arterial wall tissue, triggering neointimal hyperplasia which produces fibrotic and calcified plaques, narrowing the artery again. Drug-eluting stents (DES) slowly release medication to inhibit neointimal hyperplasia to prevent ISR but they fail in 3% to 20% of cases (2). Intravascular brachytherapy (IVBT), which uses b-emitting radionuclides to prevent ISR, is used in these failed cases. However, current dosimetry for IVBT is water based and does not consider attenuation of the radiation by heterogeneities such as the IVBT device guidewire, non-uniform distribution of calcified plaques, and stent material, or the angular dependence of dose distribution (3, 4, 5). The aim of this study was to investigate the uncertainties in clinical water based IVBT dosimetry, considering the effect of heterogeneities on dose distribution.
Materials & Methods
An inhouse Monte-Carlo based dosimetry package for IVBT applications based on Geant4 10.04 (patch 2) was developed. Patient’s artery was modelled as a 32 mm long, 8.4 mm diameter cylinder comprised of three layers: tunica media, represented with muscle, tunica intima, represented with fibrotic plaque, and tunica adventitia, represented with collagen. These layers had mass densities 1.06 g/cm3, 1.22 g/cm3 and 1.07 g/cm3 respectively. The innermost layer consisted of calcified plaque of density 1.45 g/cm3 with varying thicknesses between 0.9 and 1.9 mm with an eccentric shape and a rough surface. The stents had similar composition to Boston Scientific Synergy stents and were modelled to not overlap. The Novoste Beta-Cath 3.5F IVBT device model was used, which has a 90Sr90Y source. The geometry is shown in Figure 1a. A cylindrical scoring geometry was implemented. Two set of simulations were performed. In the first simulation called water phantom, the entire system consisted of water with unit density, and dose to water was calculated similar to the clinical water based dosimetry. In the second simulation called the artery model proper material and mass densities were assigned to each component. To ensure uncertainties below 0.8% within a 1 mm radial distance to the source and 2% within 4.2 mm from the source, 100 million decay events were simulated. The Penelope physics list was used to simulate the electromagnetic interactions between particles. Average, minimum, and maximum dose was calculated at 2.0 mm from the source center and directly and 1 mm behind the outermost stents and guidewire. Absorbed dose was normalized to 23 Gy at 2.0 mm from the source center.
Results
International Conference on Monte Carlo Techniques for Medical Applications, 2022
Compared to the water phantom (Figure 1b), average dose in the artery model (Figure 1c) was attenuated by 50.9% at 2 mm from the source centre and directly behind the guidewire and outermost stent by 66.2%, and by 69.5% 1 mm behind this region. There was significant variation in dose around the source due to the guidewire attenuating dose the most, and heterogeneous distribution of calcification.
Discussion & Conclusions
Dosimetry for IVBT based on dose rate in water is not accurate. Heterogeneities need to be considered to deliver adequate dose to the lesion area. Stent material, heterogenous distribution of calcification and the off cantered placement of the guidewire affects the uniformity of dose distribution around the source. Patients may benefit from personalized treatment planning taking dose-attenuating by different tissue/material heterogeneities into account.
References
[1] Virani, Salim, S., et al. ""Heart Disease and Stroke Statistics—2020 Update"". Circulation, vol. 141, no. 9, March 03, 2020, pp. e336. doi: 10.1161/CIR.0000000000000757.
[2] Lee M, Banka G. In-stent restenosis. Interv Cardiol Clin 2016;5: 211e220.
[3] Chiu-Tsao ST, Schaart DR, Soares CG, et al. Dose calculation formalisms and consensus dosimetry parameters for intravascular brachytherapy dosimetry: Recommendations of the AAPM Therapy Physics Committee Task Group No. 149. Med Phys 2007;34: 4126e4157.
[4] Rivard MJ, Coursey BM, DeWerd LA, et al. Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations. Med Phys 2004;31:633e674.
[5] Nath R, Amols H, Coffey C, et al. Intravascular brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task group No. 60. Med Phys 1999;26:119e152.’
[6] Agostinelli S, Allison J, Amako K, et al. Geant4da simulation toolkit. Nucl Instrum Methods Phys Res 2003;506:230e303."
Berumen-Murillo, Francisco; Enger, Shirin A.; Beaulieu, Luc
Sub-Second D (M, M) Calculation for LDR Prostate Brachytherapy Using Deep Learning Methods Proceedings Article
In: MEDICAL PHYSICS, pp. E163–E163, WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA 2022.
@inproceedings{berumen2022sub,
title = {Sub-Second D (M, M) Calculation for LDR Prostate Brachytherapy Using Deep Learning Methods},
author = {Francisco Berumen-Murillo and Shirin A. Enger and Luc Beaulieu},
year = {2022},
date = {2022-01-01},
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Weishaupt, Luca L; Vuong, Te; Thibodeau-Antonacci, Alana; Garant, A; Singh, KS; Miller, C; Martin, A; Enger, Shirin A.
A121 QUANTIFYING INTER-OBSERVER VARIABILITY IN THE SEGMENTATION OF RECTAL TUMORS IN ENDOSCOPY IMAGES AND ITS EFFECTS ON DEEP LEARNING Journal Article
In: Journal of the Canadian Association of Gastroenterology, vol. 5, no. Supplement_1, pp. 140–142, 2022.
@article{weishaupt2022a121,
title = {A121 QUANTIFYING INTER-OBSERVER VARIABILITY IN THE SEGMENTATION OF RECTAL TUMORS IN ENDOSCOPY IMAGES AND ITS EFFECTS ON DEEP LEARNING},
author = {Luca L Weishaupt and Te Vuong and Alana Thibodeau-Antonacci and A Garant and KS Singh and C Miller and A Martin and Shirin A. Enger},
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Thibodeau-Antonacci, Alana; Vuong, Te; Liontis, B; Rayes, F; Pande, S; Enger, Shirin A.
Development of a Novel MRI-Compatible Applicator for Intensity Modulated Rectal Brachytherapy Proceedings Article
In: MEDICAL PHYSICS, pp. E240–E240, WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA 2022.
@inproceedings{thibodeau2022development,
title = {Development of a Novel MRI-Compatible Applicator for Intensity Modulated Rectal Brachytherapy},
author = {Alana Thibodeau-Antonacci and Te Vuong and B Liontis and F Rayes and S Pande and Shirin A. Enger},
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Thibodeau-Antonacci, Alana; Enger, Shirin A.; Bekerat, Hamed; Vuong, Te
Gafchromic film and scintillator detector measurements in phantom with a novel intensity-modulated brachytherapy endorectal shield Proceedings Article
In: MEDICAL PHYSICS, pp. 5688–5689, WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA 2022.
@inproceedings{thibodeau2022gafchromic,
title = {Gafchromic film and scintillator detector measurements in phantom with a novel intensity-modulated brachytherapy endorectal shield},
author = {Alana Thibodeau-Antonacci and Shirin A. Enger and Hamed Bekerat and Te Vuong},
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Weishaupt, Luca L.; Vuong, Te; Thibodeau-Antonacci, Alana; Garant, A; Singh, K; Miller, C; Martin, A; Schmitt-Ulms, F; Enger, Shirin A.
PO-1325 Automated rectal tumor segmentation with inter-observer variability-based uncertainty estimates Journal Article
In: Radiotherapy and Oncology, vol. 170, pp. S1120–S1121, 2022.
@article{weishaupt2022po,
title = {PO-1325 Automated rectal tumor segmentation with inter-observer variability-based uncertainty estimates},
author = {Luca L. Weishaupt and Te Vuong and Alana Thibodeau-Antonacci and A Garant and K Singh and C Miller and A Martin and F Schmitt-Ulms and Shirin A. Enger},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
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volume = {170},
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tppubtype = {article}
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Jafarzadeh, Hossein; Mao, Ximeng; Enger, Shirin A.
Bayesian Optimization in Treatment Planning of High Dose Rate Brachytherapy Proceedings Article
In: MEDICAL PHYSICS, pp. E200–E200, WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA 2022.
@inproceedings{jafarzadeh2022bayesian,
title = {Bayesian Optimization in Treatment Planning of High Dose Rate Brachytherapy},
author = { Hossein Jafarzadeh and Ximeng Mao and Shirin A. Enger},
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2021
Thibodeau-Antonacci, Alana
Canada Graduate Scholarship – Doctoral Program award
2021.
@award{Thibodeau-Antonacci2021d,
title = {Canada Graduate Scholarship – Doctoral Program},
author = {Alana Thibodeau-Antonacci},
url = {https://www.nserc-crsng.gc.ca/students-etudiants/pg-cs/cgsd-bescd_eng.asp},
year = {2021},
date = {2021-09-01},
organization = {NSERC},
keywords = {},
pubstate = {published},
tppubtype = {award}
}
Kalinowski, Jonathan
Merit-based recruitment award for first year MSc students. award
2021.
@award{nokey,
title = {Merit-based recruitment award for first year MSc students.},
author = {Jonathan Kalinowski},
year = {2021},
date = {2021-09-01},
urldate = {2021-09-01},
organization = {McGill Medical Physics Unit},
keywords = {},
pubstate = {published},
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Esmaelbeigi, Azin
Biological & Biomedical Engineering PhD Recruitment Award award
2021.
@award{nokey,
title = {Biological & Biomedical Engineering PhD Recruitment Award },
author = {Azin Esmaelbeigi},
url = {https://www.mcgill.ca/bbme/programs/funding#BME-Recruitment-Award},
year = {2021},
date = {2021-09-01},
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Weishaupt, Luca L.; Thibodeau-Antonacci, Alana; Garant, Aurelie; Singh, Kelita; Miller, Corey; Vuong, Té; Enger, Shirin A.
Deep learning based tumor segmentation of endoscopy images for rectal cancer patients Presentation
ESTRO Annual meeting, 27.08.2021.
@misc{Weishaupt2021b,
title = {Deep learning based tumor segmentation of endoscopy images for rectal cancer patients},
author = {Luca L. Weishaupt and Alana Thibodeau-Antonacci and Aurelie Garant and Kelita Singh and Corey Miller and Té Vuong and Shirin A. Enger},
url = {https://www.estro.org/Congresses/ESTRO-2021/610/posterdiscussion34-deep-learningforauto-contouring/3710/deeplearning-basedtumorsegmentationofendoscopyimag},
year = {2021},
date = {2021-08-27},
urldate = {2021-08-27},
abstract = {Purpose or Objective
The objective of this study was to develop an automated rectal tumor segmentation algorithm from endoscopy images. The algorithm will be used in a future multimodal treatment outcome prediction model. Currently, treatment outcome prediction models rely on manual segmentations of regions of interest, which are prone to inter-observer variability. To quantify this human error and demonstrate the feasibility of automated endoscopy image segmentation, we compare three deep learning architectures.
Material and Methods
A gastrointestinal physician (G1) segmented 550 endoscopy images of rectal tumors into tumor and non-tumor regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2) contoured 319 of the images independently.
The 550 images and annotations from G1 were divided into 408 training, 82 validation, and 60 testing sets. Three deep learning architectures were trained; a fully convolutional neural network (FCN32), a U-Net, and a SegNet. These architectures have been used for robust medical image segmentation in previous studies.
All models were trained on a CPU supercomputing cluster. Data augmentation in the form of random image transformations, including scaling, rotation, shearing, Gaussian blurring, and noise addition, was used to improve the models' robustness.
The neural networks' output went through a final layer of noise removal and hole filling before evaluation. Finally, the segmentations from G2 and the neural networks' predictions were compared against the ground truth labels from G1.
Results
The FCN32, U-Net, and SegNet had average segmentation times of 0.77, 0.48, and 0.43 seconds per image, respectively. The average segmentation time per image for G1 and G2 were 10 and 8 seconds, respectively.
All the ground truth labels contained tumors, but G2 and the deep learning models did not always find tumors in the images. The scores are based on the agreement of tumor contours with G1’s ground truth and were thus only computed for images in which tumor was found. The automated segmentation algorithms consistently achieved equal or better scores than G2's manual segmentations. G2's low F1/DICE and precision scores indicate poor agreement between the manual contours.
Conclusion
There is a need for robust and accurate segmentation algorithms for rectal tumor segmentation since manual segmentation of these tumors is susceptible to significant inter-observer variability. The deep learning-based segmentation algorithms proposed in this study are more efficient and achieved a higher agreement with our manual ground truth segmentations than a second expert annotator. Future studies will investigate how to train deep learning models on multiple ground truth annotations to prevent learning observer biases.},
howpublished = {ESTRO Annual meeting},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Purpose or Objective
The objective of this study was to develop an automated rectal tumor segmentation algorithm from endoscopy images. The algorithm will be used in a future multimodal treatment outcome prediction model. Currently, treatment outcome prediction models rely on manual segmentations of regions of interest, which are prone to inter-observer variability. To quantify this human error and demonstrate the feasibility of automated endoscopy image segmentation, we compare three deep learning architectures.
Material and Methods
A gastrointestinal physician (G1) segmented 550 endoscopy images of rectal tumors into tumor and non-tumor regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2) contoured 319 of the images independently.
The 550 images and annotations from G1 were divided into 408 training, 82 validation, and 60 testing sets. Three deep learning architectures were trained; a fully convolutional neural network (FCN32), a U-Net, and a SegNet. These architectures have been used for robust medical image segmentation in previous studies.
All models were trained on a CPU supercomputing cluster. Data augmentation in the form of random image transformations, including scaling, rotation, shearing, Gaussian blurring, and noise addition, was used to improve the models' robustness.
The neural networks' output went through a final layer of noise removal and hole filling before evaluation. Finally, the segmentations from G2 and the neural networks' predictions were compared against the ground truth labels from G1.
Results
The FCN32, U-Net, and SegNet had average segmentation times of 0.77, 0.48, and 0.43 seconds per image, respectively. The average segmentation time per image for G1 and G2 were 10 and 8 seconds, respectively.
All the ground truth labels contained tumors, but G2 and the deep learning models did not always find tumors in the images. The scores are based on the agreement of tumor contours with G1’s ground truth and were thus only computed for images in which tumor was found. The automated segmentation algorithms consistently achieved equal or better scores than G2's manual segmentations. G2's low F1/DICE and precision scores indicate poor agreement between the manual contours.
Conclusion
There is a need for robust and accurate segmentation algorithms for rectal tumor segmentation since manual segmentation of these tumors is susceptible to significant inter-observer variability. The deep learning-based segmentation algorithms proposed in this study are more efficient and achieved a higher agreement with our manual ground truth segmentations than a second expert annotator. Future studies will investigate how to train deep learning models on multiple ground truth annotations to prevent learning observer biases.
The objective of this study was to develop an automated rectal tumor segmentation algorithm from endoscopy images. The algorithm will be used in a future multimodal treatment outcome prediction model. Currently, treatment outcome prediction models rely on manual segmentations of regions of interest, which are prone to inter-observer variability. To quantify this human error and demonstrate the feasibility of automated endoscopy image segmentation, we compare three deep learning architectures.
Material and Methods
A gastrointestinal physician (G1) segmented 550 endoscopy images of rectal tumors into tumor and non-tumor regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2) contoured 319 of the images independently.
The 550 images and annotations from G1 were divided into 408 training, 82 validation, and 60 testing sets. Three deep learning architectures were trained; a fully convolutional neural network (FCN32), a U-Net, and a SegNet. These architectures have been used for robust medical image segmentation in previous studies.
All models were trained on a CPU supercomputing cluster. Data augmentation in the form of random image transformations, including scaling, rotation, shearing, Gaussian blurring, and noise addition, was used to improve the models' robustness.
The neural networks' output went through a final layer of noise removal and hole filling before evaluation. Finally, the segmentations from G2 and the neural networks' predictions were compared against the ground truth labels from G1.
Results
The FCN32, U-Net, and SegNet had average segmentation times of 0.77, 0.48, and 0.43 seconds per image, respectively. The average segmentation time per image for G1 and G2 were 10 and 8 seconds, respectively.
All the ground truth labels contained tumors, but G2 and the deep learning models did not always find tumors in the images. The scores are based on the agreement of tumor contours with G1’s ground truth and were thus only computed for images in which tumor was found. The automated segmentation algorithms consistently achieved equal or better scores than G2's manual segmentations. G2's low F1/DICE and precision scores indicate poor agreement between the manual contours.
Conclusion
There is a need for robust and accurate segmentation algorithms for rectal tumor segmentation since manual segmentation of these tumors is susceptible to significant inter-observer variability. The deep learning-based segmentation algorithms proposed in this study are more efficient and achieved a higher agreement with our manual ground truth segmentations than a second expert annotator. Future studies will investigate how to train deep learning models on multiple ground truth annotations to prevent learning observer biases.
Lecavalier-Barsoum, Magali; Khosrow-Khavar, Farzin; Asiev, Krum; Popovic, Marija; Vuong, Te; Enger, Shirin A.
Utilization of brachytherapy in Quebec, Canada Journal Article
In: Brachytherapy, pp. S1538–4721(21)00452–9, 2021, ISSN: 1873-1449.
@article{lecavalier-barsoum_utilization_2021,
title = {Utilization of brachytherapy in Quebec, Canada},
author = {Magali Lecavalier-Barsoum and Farzin Khosrow-Khavar and Krum Asiev and Marija Popovic and Te Vuong and Shirin A. Enger},
doi = {10.1016/j.brachy.2021.07.002},
issn = {1873-1449},
year = {2021},
date = {2021-08-01},
journal = {Brachytherapy},
pages = {S1538--4721(21)00452--9},
abstract = {BACKGROUND AND PURPOSE: Despite the excellent clinical outcomes from brachytherapy treatments compared with other modalities and the low associated costs, there have been reports of a decline in utilization of brachytherapy. The aim of this study was to investigate in detail the trend in utilization of brachytherapy in the province of Québec, Canada, from 2011 to 2019.
MATERIALS AND METHODS: All radiotherapy clinics in the province of Quebec, and among these the clinics that provide brachytherapy treatments, were identified. This observational retrospective cohort study involved analysis of data compiled by the Ministère de la Santé et des Services Sociaux du Québec for the period of 2011 to end of 2019 on all brachytherapy procedures performed in the province of Quebec. Time series graphs were used to describe the number of high dose rate (HDR) and low dose rate (LDR) brachytherapy treatments during the studied time period. Statistical analysis was conducted using R statistical software.
RESULTS: Between 2011 and 2019, 12 hospitals in the province of Québec provided radiotherapy treatments, and all of them offered brachytherapy services. The median annual number of brachytherapy sessions was 4413 (range 3930-4829). HDR brachytherapy represented over 90% of all brachytherapy treatments throughout the study period. Significant changes over time were observed in the number of treatments: at least 5% change was seen only for the two most common subtypes of brachytherapy, HDR interstitial and HDR intracavitary, with an increase of 9.6% and a decrease of 9.2%, respectively. The use of other subtypes of brachytherapy (HDR-plesiotherapy, LDR-interstitial, LDR-intracavitary, LDR-eye plaque) was stable between 2011 and 2019, with ≤ 2.5% variation.
CONCLUSION: This study demonstrates an overall steady use of brachytherapy between 2011 and 2019 in Quebec. Brachytherapy offers numerous advantages for the treatment of diverse cancer sites. Although more sophisticated external beam radiotherapy treatments have emerged in the last decades, the precision and cost-effectiveness of brachytherapy remain unbeaten. To ensure the continued use and availability of brachytherapy, governments must put in place policies and regulations to that effect. Training and exposure of future health care professionals to brachytherapy within Quebec and Canada is essential to provide all patients the same access to this life saving modality.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND AND PURPOSE: Despite the excellent clinical outcomes from brachytherapy treatments compared with other modalities and the low associated costs, there have been reports of a decline in utilization of brachytherapy. The aim of this study was to investigate in detail the trend in utilization of brachytherapy in the province of Québec, Canada, from 2011 to 2019.
MATERIALS AND METHODS: All radiotherapy clinics in the province of Quebec, and among these the clinics that provide brachytherapy treatments, were identified. This observational retrospective cohort study involved analysis of data compiled by the Ministère de la Santé et des Services Sociaux du Québec for the period of 2011 to end of 2019 on all brachytherapy procedures performed in the province of Quebec. Time series graphs were used to describe the number of high dose rate (HDR) and low dose rate (LDR) brachytherapy treatments during the studied time period. Statistical analysis was conducted using R statistical software.
RESULTS: Between 2011 and 2019, 12 hospitals in the province of Québec provided radiotherapy treatments, and all of them offered brachytherapy services. The median annual number of brachytherapy sessions was 4413 (range 3930-4829). HDR brachytherapy represented over 90% of all brachytherapy treatments throughout the study period. Significant changes over time were observed in the number of treatments: at least 5% change was seen only for the two most common subtypes of brachytherapy, HDR interstitial and HDR intracavitary, with an increase of 9.6% and a decrease of 9.2%, respectively. The use of other subtypes of brachytherapy (HDR-plesiotherapy, LDR-interstitial, LDR-intracavitary, LDR-eye plaque) was stable between 2011 and 2019, with ≤ 2.5% variation.
CONCLUSION: This study demonstrates an overall steady use of brachytherapy between 2011 and 2019 in Quebec. Brachytherapy offers numerous advantages for the treatment of diverse cancer sites. Although more sophisticated external beam radiotherapy treatments have emerged in the last decades, the precision and cost-effectiveness of brachytherapy remain unbeaten. To ensure the continued use and availability of brachytherapy, governments must put in place policies and regulations to that effect. Training and exposure of future health care professionals to brachytherapy within Quebec and Canada is essential to provide all patients the same access to this life saving modality.
MATERIALS AND METHODS: All radiotherapy clinics in the province of Quebec, and among these the clinics that provide brachytherapy treatments, were identified. This observational retrospective cohort study involved analysis of data compiled by the Ministère de la Santé et des Services Sociaux du Québec for the period of 2011 to end of 2019 on all brachytherapy procedures performed in the province of Quebec. Time series graphs were used to describe the number of high dose rate (HDR) and low dose rate (LDR) brachytherapy treatments during the studied time period. Statistical analysis was conducted using R statistical software.
RESULTS: Between 2011 and 2019, 12 hospitals in the province of Québec provided radiotherapy treatments, and all of them offered brachytherapy services. The median annual number of brachytherapy sessions was 4413 (range 3930-4829). HDR brachytherapy represented over 90% of all brachytherapy treatments throughout the study period. Significant changes over time were observed in the number of treatments: at least 5% change was seen only for the two most common subtypes of brachytherapy, HDR interstitial and HDR intracavitary, with an increase of 9.6% and a decrease of 9.2%, respectively. The use of other subtypes of brachytherapy (HDR-plesiotherapy, LDR-interstitial, LDR-intracavitary, LDR-eye plaque) was stable between 2011 and 2019, with ≤ 2.5% variation.
CONCLUSION: This study demonstrates an overall steady use of brachytherapy between 2011 and 2019 in Quebec. Brachytherapy offers numerous advantages for the treatment of diverse cancer sites. Although more sophisticated external beam radiotherapy treatments have emerged in the last decades, the precision and cost-effectiveness of brachytherapy remain unbeaten. To ensure the continued use and availability of brachytherapy, governments must put in place policies and regulations to that effect. Training and exposure of future health care professionals to brachytherapy within Quebec and Canada is essential to provide all patients the same access to this life saving modality.
Thibodeau-Antonacci, Alana; Jafarzadeh, Hossein; Carroll, Liam; Weishaupt, Luca L.
Mitacs Globalink Research Award award
2021.
@award{Thibodeau-Antonacci2021c,
title = {Mitacs Globalink Research Award},
author = {Alana Thibodeau-Antonacci and Hossein Jafarzadeh and Liam Carroll and Luca L. Weishaupt},
url = {https://www.mitacs.ca/en/programs/globalink/globalink-research-award},
year = {2021},
date = {2021-07-01},
urldate = {2021-07-01},
organization = {MITACS},
abstract = {The Mitacs Globalink Research Award (GRA) supports research collaborations between Canada and select partner organizations and eligible countries and regions. It was awarded to Alana Thibodeau-Antonacci, Hossein Jafarzadeh, Liam Carroll and Luca L. Weishaupt.
Under the joint supervision of a home and host professor, successful senior undergraduate students, graduate students, as well as postdoctoral fellows will receive a $6,000 research award to conduct a 12- to 24-week research project in the other country. Awards are offered in partnership with Mitacs’s Canadian academic partners (and, in some cases, with Mitacs’s international partners) and are subject to available funding. },
howpublished = {Mitacs},
keywords = {},
pubstate = {published},
tppubtype = {award}
}
The Mitacs Globalink Research Award (GRA) supports research collaborations between Canada and select partner organizations and eligible countries and regions. It was awarded to Alana Thibodeau-Antonacci, Hossein Jafarzadeh, Liam Carroll and Luca L. Weishaupt.
Under the joint supervision of a home and host professor, successful senior undergraduate students, graduate students, as well as postdoctoral fellows will receive a $6,000 research award to conduct a 12- to 24-week research project in the other country. Awards are offered in partnership with Mitacs’s Canadian academic partners (and, in some cases, with Mitacs’s international partners) and are subject to available funding.
Under the joint supervision of a home and host professor, successful senior undergraduate students, graduate students, as well as postdoctoral fellows will receive a $6,000 research award to conduct a 12- to 24-week research project in the other country. Awards are offered in partnership with Mitacs’s Canadian academic partners (and, in some cases, with Mitacs’s international partners) and are subject to available funding.
Weishaupt, Luca L.; Thibodeau-Antonacci, Alana; Garant, Aurelie; Singh, Kelita; Miller, Corey; Vuong, Té; Enger, Shirin A.
Inter-Observer Variability and Deep Learning in Rectal Tumor Segmentation from Endoscopy Images Presentation
The COMP Annual Scientific Meeting 2021, 22.06.2021.
@misc{Weishaupt2021c,
title = {Inter-Observer Variability and Deep Learning in Rectal Tumor Segmentation from Endoscopy Images},
author = {Luca L. Weishaupt and Alana Thibodeau-Antonacci and Aurelie Garant and Kelita Singh and Corey Miller and Té Vuong and Shirin A. Enger},
year = {2021},
date = {2021-06-22},
urldate = {2021-06-22},
abstract = {Purpose
To develop an automated rectal tumor segmentation algorithm from endoscopy images.
Material/Methods
A gastrointestinal physician (G1) segmented 2005 endoscopy images into tumor and non-tumor
regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2)
contoured the images independently.
Three deep-learning architectures used for robust medical image segmentation in previous
studies were trained: a fully convolutional neural network (FCN32), a U-Net, and a SegNet.
Since the majority of the images did not contain tumors, two methods were compared for
training. Models were trained using only tumor images (M1) and all images (M2). G1’s images
and annotations were divided into 408 training, 82 validation, and 60 testing sets for M1, 1181
training, 372 validation, and 452 testing sets for M2.
Finally, segmentations from G2 and neural networks' predictions were compared against ground
truth labels from G1, and F1 scores were computed for images where both physicians found
tumors.
Results
The deep-learning segmentation took less than 1 second, while manual segmentation took
approximately 10 seconds per image.
The M1’s models consistently achieved equal or better scores (SegNet F1:0.80±0.08) than G2's
manual segmentations (F1:0.68±0.25). G2's low F1/DICE and precision scores indicate poor
agreement between the manual contours. Models from M2 achieved lower scores than G2 and
M1’s models since they demonstrated a strong bias towards predicting no tumor for all images.
Conclusion
Future studies will investigate training on an equal number of images with/without tumor, using
ground truth contours from multiple experts simultaneously.},
howpublished = {The COMP Annual Scientific Meeting 2021},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Purpose
To develop an automated rectal tumor segmentation algorithm from endoscopy images.
Material/Methods
A gastrointestinal physician (G1) segmented 2005 endoscopy images into tumor and non-tumor
regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2)
contoured the images independently.
Three deep-learning architectures used for robust medical image segmentation in previous
studies were trained: a fully convolutional neural network (FCN32), a U-Net, and a SegNet.
Since the majority of the images did not contain tumors, two methods were compared for
training. Models were trained using only tumor images (M1) and all images (M2). G1’s images
and annotations were divided into 408 training, 82 validation, and 60 testing sets for M1, 1181
training, 372 validation, and 452 testing sets for M2.
Finally, segmentations from G2 and neural networks' predictions were compared against ground
truth labels from G1, and F1 scores were computed for images where both physicians found
tumors.
Results
The deep-learning segmentation took less than 1 second, while manual segmentation took
approximately 10 seconds per image.
The M1’s models consistently achieved equal or better scores (SegNet F1:0.80±0.08) than G2's
manual segmentations (F1:0.68±0.25). G2's low F1/DICE and precision scores indicate poor
agreement between the manual contours. Models from M2 achieved lower scores than G2 and
M1’s models since they demonstrated a strong bias towards predicting no tumor for all images.
Conclusion
Future studies will investigate training on an equal number of images with/without tumor, using
ground truth contours from multiple experts simultaneously.
To develop an automated rectal tumor segmentation algorithm from endoscopy images.
Material/Methods
A gastrointestinal physician (G1) segmented 2005 endoscopy images into tumor and non-tumor
regions. To quantify the inter-observer variability, a second gastrointestinal physician (G2)
contoured the images independently.
Three deep-learning architectures used for robust medical image segmentation in previous
studies were trained: a fully convolutional neural network (FCN32), a U-Net, and a SegNet.
Since the majority of the images did not contain tumors, two methods were compared for
training. Models were trained using only tumor images (M1) and all images (M2). G1’s images
and annotations were divided into 408 training, 82 validation, and 60 testing sets for M1, 1181
training, 372 validation, and 452 testing sets for M2.
Finally, segmentations from G2 and neural networks' predictions were compared against ground
truth labels from G1, and F1 scores were computed for images where both physicians found
tumors.
Results
The deep-learning segmentation took less than 1 second, while manual segmentation took
approximately 10 seconds per image.
The M1’s models consistently achieved equal or better scores (SegNet F1:0.80±0.08) than G2's
manual segmentations (F1:0.68±0.25). G2's low F1/DICE and precision scores indicate poor
agreement between the manual contours. Models from M2 achieved lower scores than G2 and
M1’s models since they demonstrated a strong bias towards predicting no tumor for all images.
Conclusion
Future studies will investigate training on an equal number of images with/without tumor, using
ground truth contours from multiple experts simultaneously.
Morcos, Marc; Antaki, Majd; Thibodeau-Antonacci, Alana; Kalinowski, Jonathan; Glickman, Harry; Enger, Shirin A.
RapidBrachyMCTPS: An open-source dose calculation and optimization tool for brachytherapy research Presentation
COMP, 01.06.2021.
@misc{Morcos2021c,
title = {RapidBrachyMCTPS: An open-source dose calculation and optimization tool for brachytherapy research},
author = {Marc Morcos and Majd Antaki and Alana Thibodeau-Antonacci and Jonathan Kalinowski and Harry Glickman and Shirin A. Enger},
year = {2021},
date = {2021-06-01},
howpublished = {COMP},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Thibodeau-Antonacci, Alana; Vuong, Té; Bekerat, Hamed; Liang, Liheng; Enger, Shirin A.
2021.
@award{Thibodeau-Antonacci2021b,
title = {Development of a Dynamic Shielding Intensity-Modulated Brachytherapy Applicator for the Treatment of Rectal Cancer},
author = {Alana Thibodeau-Antonacci and Té Vuong and Hamed Bekerat and Liheng Liang and Shirin A. Enger},
url = {https://curietherapi.es/},
year = {2021},
date = {2021-05-23},
urldate = {2021-05-23},
organization = {Curietherapies},
abstract = {Oral presentation given online at the annual congress of Curietherapies https://curietherapi.es/},
howpublished = {Annual Congress of Curietherapies},
keywords = {},
pubstate = {published},
tppubtype = {award}
}
Oral presentation given online at the annual congress of Curietherapies https://curietherapi.es/
Morcos, Marc; Viswanathan, Akila N.; Enger, Shirin A.
In: Medical Physics, vol. 48, no. 5, pp. 2604–2613, 2021, ISSN: 2473-4209.
@article{morcos_impact_2021,
title = {On the impact of absorbed dose specification, tissue heterogeneities, and applicator heterogeneities on Monte Carlo-based dosimetry of Ir-192, Se-75, and Yb-169 in conventional and intensity-modulated brachytherapy for the treatment of cervical cancer},
author = {Marc Morcos and Akila N. Viswanathan and Shirin A. Enger},
doi = {10.1002/mp.14802},
issn = {2473-4209},
year = {2021},
date = {2021-05-01},
journal = {Medical Physics},
volume = {48},
number = {5},
pages = {2604--2613},
abstract = {PURPOSE: The purpose of this study was to evaluate the impact of dose reporting schemes and tissue/applicator heterogeneities for 192 Ir-, 75 Se-, and 169 Yb-based MRI-guided conventional and intensity-modulated brachytherapy. METHODS AND MATERIALS: Treatment plans using a variety of dose reporting and tissue/applicator segmentation schemes were generated for a cohort (n = 10) of cervical cancer patients treated with 192 Ir-based Venezia brachytherapy. Dose calculations were performed using RapidBrachyMCTPS, a Geant4-based research Monte Carlo treatment planning system. Ultimately, five dose calculation scenarios were evaluated: (a) dose to water in water (Dw,w ); (b) Dw,w taking the applicator material into consideration (Dw,wApp ); (c) dose to water in medium (Dw,m ); (d and e) dose to medium in medium with mass densities assigned either nominally per structure (Dm,m (Nom) ) or voxel-by-voxel (Dm,m ).
RESULTS: Ignoring the plastic Venezia applicator (Dw,wApp ) overestimates Dm,m by up to 1% (average) with high energy source (192 Ir and 75 Se) and up to 2% with 169 Yb. Scoring dose to water (Dw,wApp or Dw,m ) generally overestimates dose and this effect increases with decreasing photon energy. Reporting dose other than Dm,m (or Dm,m Nom ) for 169 Yb-based conventional and intensity-modulated brachytherapy leads to a simultaneous overestimation (up to 4%) of CTVHR D90 and underestimation (up to 2%) of bladder D2cc due to a significant dip in the mass-energy absorption ratios at the depths of nearby targets and OARs. Using a nominal mass-density assignment per structure, rather than a CT-derived voxel-by-voxel assignment for MRI-guided brachytherapy, amounts to a dose error up to 1% for all radionuclides considered.
CONCLUSIONS: The effects of the considered dose reporting schemes trend correspondingly between conventional and intensity-modulated brachytherapy. In the absence of CT-derived mass densities, MRI-only-based dosimetry can adequately approximate Dm,m by assigning nominal mass densities to structures. Tissue and applicator heterogeneities do not significantly impact dosimetry for 192 Ir and 75 Se, but do for 169 Yb; dose reporting must be explicitly defined since Dw,m and Dw,w may overstate the dosimetric benefits.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
PURPOSE: The purpose of this study was to evaluate the impact of dose reporting schemes and tissue/applicator heterogeneities for 192 Ir-, 75 Se-, and 169 Yb-based MRI-guided conventional and intensity-modulated brachytherapy. METHODS AND MATERIALS: Treatment plans using a variety of dose reporting and tissue/applicator segmentation schemes were generated for a cohort (n = 10) of cervical cancer patients treated with 192 Ir-based Venezia brachytherapy. Dose calculations were performed using RapidBrachyMCTPS, a Geant4-based research Monte Carlo treatment planning system. Ultimately, five dose calculation scenarios were evaluated: (a) dose to water in water (Dw,w ); (b) Dw,w taking the applicator material into consideration (Dw,wApp ); (c) dose to water in medium (Dw,m ); (d and e) dose to medium in medium with mass densities assigned either nominally per structure (Dm,m (Nom) ) or voxel-by-voxel (Dm,m ).
RESULTS: Ignoring the plastic Venezia applicator (Dw,wApp ) overestimates Dm,m by up to 1% (average) with high energy source (192 Ir and 75 Se) and up to 2% with 169 Yb. Scoring dose to water (Dw,wApp or Dw,m ) generally overestimates dose and this effect increases with decreasing photon energy. Reporting dose other than Dm,m (or Dm,m Nom ) for 169 Yb-based conventional and intensity-modulated brachytherapy leads to a simultaneous overestimation (up to 4%) of CTVHR D90 and underestimation (up to 2%) of bladder D2cc due to a significant dip in the mass-energy absorption ratios at the depths of nearby targets and OARs. Using a nominal mass-density assignment per structure, rather than a CT-derived voxel-by-voxel assignment for MRI-guided brachytherapy, amounts to a dose error up to 1% for all radionuclides considered.
CONCLUSIONS: The effects of the considered dose reporting schemes trend correspondingly between conventional and intensity-modulated brachytherapy. In the absence of CT-derived mass densities, MRI-only-based dosimetry can adequately approximate Dm,m by assigning nominal mass densities to structures. Tissue and applicator heterogeneities do not significantly impact dosimetry for 192 Ir and 75 Se, but do for 169 Yb; dose reporting must be explicitly defined since Dw,m and Dw,w may overstate the dosimetric benefits.
RESULTS: Ignoring the plastic Venezia applicator (Dw,wApp ) overestimates Dm,m by up to 1% (average) with high energy source (192 Ir and 75 Se) and up to 2% with 169 Yb. Scoring dose to water (Dw,wApp or Dw,m ) generally overestimates dose and this effect increases with decreasing photon energy. Reporting dose other than Dm,m (or Dm,m Nom ) for 169 Yb-based conventional and intensity-modulated brachytherapy leads to a simultaneous overestimation (up to 4%) of CTVHR D90 and underestimation (up to 2%) of bladder D2cc due to a significant dip in the mass-energy absorption ratios at the depths of nearby targets and OARs. Using a nominal mass-density assignment per structure, rather than a CT-derived voxel-by-voxel assignment for MRI-guided brachytherapy, amounts to a dose error up to 1% for all radionuclides considered.
CONCLUSIONS: The effects of the considered dose reporting schemes trend correspondingly between conventional and intensity-modulated brachytherapy. In the absence of CT-derived mass densities, MRI-only-based dosimetry can adequately approximate Dm,m by assigning nominal mass densities to structures. Tissue and applicator heterogeneities do not significantly impact dosimetry for 192 Ir and 75 Se, but do for 169 Yb; dose reporting must be explicitly defined since Dw,m and Dw,w may overstate the dosimetric benefits.
Thibodeau-Antonacci, Alana; Vuong, Té; Bekerat, Hamed; Childress, Lilian; Enger, Shirin A.
OC-0112 development of a dynamic-shielding intensity modulated endorectal brachytherapy applicator Presentation
Radiotherapy and Oncology, 01.05.2021, ISBN: 0167-8140, 1879-0887.
@misc{Thibodeau-Antonacci2021,
title = {OC-0112 development of a dynamic-shielding intensity modulated endorectal brachytherapy applicator},
author = {Alana Thibodeau-Antonacci and Té Vuong and Hamed Bekerat and Lilian Childress and Shirin A. Enger},
url = {https://www.thegreenjournal.com/article/S0167-8140(21)06316-7/fulltext},
doi = {10.1016/S0167-8140(21)06316-7},
isbn = {0167-8140, 1879-0887},
year = {2021},
date = {2021-05-01},
abstract = {www.thegreenjournal.com},
howpublished = {Radiotherapy and Oncology},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Morcos, Marc; Enger, Shirin A.
A novel minimally invasive IMBT delivery system for cervical cancer Presentation
JGH-Lady Davis Institute, 01.02.2021.
@misc{Morcos2021b,
title = {A novel minimally invasive IMBT delivery system for cervical cancer},
author = {Marc Morcos and Shirin A. Enger},
year = {2021},
date = {2021-02-01},
howpublished = {JGH-Lady Davis Institute},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Morcos, Marc; Antaki, Majd; Viswanathan, Akila N.; Enger, Shirin A.
A novel minimally invasive dynamic-shield, intensity-modulated brachytherapy system for the treatment of cervical cancer Journal Article
In: Medical Physics, vol. 48, no. 1, pp. 71–79, 2021, ISSN: 2473-4209.
@article{morcos_novel_2021,
title = {A novel minimally invasive dynamic-shield, intensity-modulated brachytherapy system for the treatment of cervical cancer},
author = {Marc Morcos and Majd Antaki and Akila N. Viswanathan and Shirin A. Enger},
doi = {10.1002/mp.14459},
issn = {2473-4209},
year = {2021},
date = {2021-01-01},
journal = {Medical Physics},
volume = {48},
number = {1},
pages = {71--79},
abstract = {PURPOSE: To present a novel, MRI-compatible dynamicshield intensity modulated brachytherapy (IMBT) applicator and delivery system using 192 Ir, 75 Se, and 169 Yb radioisotopes for the treatment of locally advanced cervical cancer. Needle-free IMBT is a promising technique for improving target coverage and organs at risk (OAR) sparing.
METHODS AND MATERIALS: The IMBT delivery system dynamically controls the rotation of a novel tungsten shield placed inside an MRI-compatible, 6-mm wide intrauterine tandem. Using 36 cervical cancer cases, conventional intracavitary brachytherapy (IC-BT) and intracavitary/interstitial brachytherapy (IC/IS-BT) (10Ci 192 Ir) plans were compared to IMBT (10Ci 192 Ir; 11.5Ci 75 Se; 44Ci 169 Yb). All plans were generated using the Geant4-based Monte Carlo dose calculation engine, RapidBrachyMC. Treatment plans were optimized then normalized to the same high-risk clinical target volume (HR-CTV) D90 and the D2cc for bladder, rectum, and sigmoid in the research brachytherapy planning system, RapidBrachyMCTPS. Plans were renormalized until either of the three OAR reached dose limits to calculate the maximum achievable HR-CTV D90 and D98 . RESULTS: Compared to IC-BT, IMBT with either of the three radionuclides significantly improves the HR-CTV D90 and D98 by up to 5.2% ± 0.3% (P textless 0.001) and 6.7% ± 0.5% (P textless 0.001), respectively, with the largest dosimetric enhancement when using 169 Yb followed by 75 Se and then 192 Ir. Similarly, D2cc for all OAR improved with IMBT by up to 7.7% ± 0.6% (P textless 0.001). For IC/IS-BT cases, needle-free IMBT achieved clinically acceptable plans with 169 Yb-based IMBT further improving HR-CTV D98 by 1.5% ± 0.2% (P = 0.034) and decreasing sigmoid D2cc by 1.9% ± 0.4% (P = 0.048). Delivery times for IMBT are increased by a factor of 1.7, 3.3, and 2.3 for 192 Ir, 75 Se, and 169 Yb, respectively, relative to conventional 192 Ir BT.
CONCLUSIONS: Dynamic shield IMBT provides a promising alternative to conventional IC- and IC/IS-BT techniques with significant dosimetric enhancements and even greater improvements with intermediate energy radionuclides. The ability to deliver a highly conformal, OAR-sparing dose without IS needles provides a simplified method for improving the therapeutic ratio less invasively and in a less resource intensive manner.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
PURPOSE: To present a novel, MRI-compatible dynamicshield intensity modulated brachytherapy (IMBT) applicator and delivery system using 192 Ir, 75 Se, and 169 Yb radioisotopes for the treatment of locally advanced cervical cancer. Needle-free IMBT is a promising technique for improving target coverage and organs at risk (OAR) sparing.
METHODS AND MATERIALS: The IMBT delivery system dynamically controls the rotation of a novel tungsten shield placed inside an MRI-compatible, 6-mm wide intrauterine tandem. Using 36 cervical cancer cases, conventional intracavitary brachytherapy (IC-BT) and intracavitary/interstitial brachytherapy (IC/IS-BT) (10Ci 192 Ir) plans were compared to IMBT (10Ci 192 Ir; 11.5Ci 75 Se; 44Ci 169 Yb). All plans were generated using the Geant4-based Monte Carlo dose calculation engine, RapidBrachyMC. Treatment plans were optimized then normalized to the same high-risk clinical target volume (HR-CTV) D90 and the D2cc for bladder, rectum, and sigmoid in the research brachytherapy planning system, RapidBrachyMCTPS. Plans were renormalized until either of the three OAR reached dose limits to calculate the maximum achievable HR-CTV D90 and D98 . RESULTS: Compared to IC-BT, IMBT with either of the three radionuclides significantly improves the HR-CTV D90 and D98 by up to 5.2% ± 0.3% (P textless 0.001) and 6.7% ± 0.5% (P textless 0.001), respectively, with the largest dosimetric enhancement when using 169 Yb followed by 75 Se and then 192 Ir. Similarly, D2cc for all OAR improved with IMBT by up to 7.7% ± 0.6% (P textless 0.001). For IC/IS-BT cases, needle-free IMBT achieved clinically acceptable plans with 169 Yb-based IMBT further improving HR-CTV D98 by 1.5% ± 0.2% (P = 0.034) and decreasing sigmoid D2cc by 1.9% ± 0.4% (P = 0.048). Delivery times for IMBT are increased by a factor of 1.7, 3.3, and 2.3 for 192 Ir, 75 Se, and 169 Yb, respectively, relative to conventional 192 Ir BT.
CONCLUSIONS: Dynamic shield IMBT provides a promising alternative to conventional IC- and IC/IS-BT techniques with significant dosimetric enhancements and even greater improvements with intermediate energy radionuclides. The ability to deliver a highly conformal, OAR-sparing dose without IS needles provides a simplified method for improving the therapeutic ratio less invasively and in a less resource intensive manner.
METHODS AND MATERIALS: The IMBT delivery system dynamically controls the rotation of a novel tungsten shield placed inside an MRI-compatible, 6-mm wide intrauterine tandem. Using 36 cervical cancer cases, conventional intracavitary brachytherapy (IC-BT) and intracavitary/interstitial brachytherapy (IC/IS-BT) (10Ci 192 Ir) plans were compared to IMBT (10Ci 192 Ir; 11.5Ci 75 Se; 44Ci 169 Yb). All plans were generated using the Geant4-based Monte Carlo dose calculation engine, RapidBrachyMC. Treatment plans were optimized then normalized to the same high-risk clinical target volume (HR-CTV) D90 and the D2cc for bladder, rectum, and sigmoid in the research brachytherapy planning system, RapidBrachyMCTPS. Plans were renormalized until either of the three OAR reached dose limits to calculate the maximum achievable HR-CTV D90 and D98 . RESULTS: Compared to IC-BT, IMBT with either of the three radionuclides significantly improves the HR-CTV D90 and D98 by up to 5.2% ± 0.3% (P textless 0.001) and 6.7% ± 0.5% (P textless 0.001), respectively, with the largest dosimetric enhancement when using 169 Yb followed by 75 Se and then 192 Ir. Similarly, D2cc for all OAR improved with IMBT by up to 7.7% ± 0.6% (P textless 0.001). For IC/IS-BT cases, needle-free IMBT achieved clinically acceptable plans with 169 Yb-based IMBT further improving HR-CTV D98 by 1.5% ± 0.2% (P = 0.034) and decreasing sigmoid D2cc by 1.9% ± 0.4% (P = 0.048). Delivery times for IMBT are increased by a factor of 1.7, 3.3, and 2.3 for 192 Ir, 75 Se, and 169 Yb, respectively, relative to conventional 192 Ir BT.
CONCLUSIONS: Dynamic shield IMBT provides a promising alternative to conventional IC- and IC/IS-BT techniques with significant dosimetric enhancements and even greater improvements with intermediate energy radionuclides. The ability to deliver a highly conformal, OAR-sparing dose without IS needles provides a simplified method for improving the therapeutic ratio less invasively and in a less resource intensive manner.
Morcos, Marc; Viswanathan, Akila N.; Enger, Shirin A.
In: Medical Physics, vol. 48, no. 5, pp. 2604–2613, 2021, ISSN: 2473-4209, (_eprint: https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1002/mp.14802).
@article{morcos_impact_2021b,
title = {On the impact of absorbed dose specification, tissue heterogeneities, and applicator heterogeneities on Monte Carlo-based dosimetry of Ir-192, Se-75, and Yb-169 in conventional and intensity-modulated brachytherapy for the treatment of cervical cancer},
author = {Marc Morcos and Akila N. Viswanathan and Shirin A. Enger},
url = {https://aapm.onlinelibrary.wiley.com/doi/abs/10.1002/mp.14802},
doi = {10.1002/mp.14802},
issn = {2473-4209},
year = {2021},
date = {2021-01-01},
urldate = {2021-09-08},
journal = {Medical Physics},
volume = {48},
number = {5},
pages = {2604--2613},
abstract = {Purpose The purpose of this study was to evaluate the impact of dose reporting schemes and tissue/applicator heterogeneities for 192Ir-, 75Se-, and 169Yb-based MRI-guided conventional and intensity-modulated brachytherapy. Methods and Materials Treatment plans using a variety of dose reporting and tissue/applicator segmentation schemes were generated for a cohort (n = 10) of cervical cancer patients treated with 192Ir-based Venezia brachytherapy. Dose calculations were performed using RapidBrachyMCTPS, a Geant4-based research Monte Carlo treatment planning system. Ultimately, five dose calculation scenarios were evaluated: (a) dose to water in water (Dw,w); (b) Dw,w taking the applicator material into consideration (Dw,wApp); (c) dose to water in medium (Dw,m); (d and e) dose to medium in medium with mass densities assigned either nominally per structure (Dm,m (Nom)) or voxel-by-voxel (Dm,m). Results Ignoring the plastic Venezia applicator (Dw,wApp) overestimates Dm,m by up to 1% (average) with high energy source (192Ir and 75Se) and up to 2% with 169Yb. Scoring dose to water (Dw,wApp or Dw,m) generally overestimates dose and this effect increases with decreasing photon energy. Reporting dose other than Dm,m (or Dm,m Nom) for 169Yb-based conventional and intensity-modulated brachytherapy leads to a simultaneous overestimation (up to 4%) of CTVHR D90 and underestimation (up to 2%) of bladder D2cc due to a significant dip in the mass-energy absorption ratios at the depths of nearby targets and OARs. Using a nominal mass-density assignment per structure, rather than a CT-derived voxel-by-voxel assignment for MRI-guided brachytherapy, amounts to a dose error up to 1% for all radionuclides considered. Conclusions The effects of the considered dose reporting schemes trend correspondingly between conventional and intensity-modulated brachytherapy. In the absence of CT-derived mass densities, MRI-only-based dosimetry can adequately approximate Dm,m by assigning nominal mass densities to structures. Tissue and applicator heterogeneities do not significantly impact dosimetry for 192Ir and 75Se, but do for 169Yb; dose reporting must be explicitly defined since Dw,m and Dw,w may overstate the dosimetric benefits.},
note = {_eprint: https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1002/mp.14802},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Purpose The purpose of this study was to evaluate the impact of dose reporting schemes and tissue/applicator heterogeneities for 192Ir-, 75Se-, and 169Yb-based MRI-guided conventional and intensity-modulated brachytherapy. Methods and Materials Treatment plans using a variety of dose reporting and tissue/applicator segmentation schemes were generated for a cohort (n = 10) of cervical cancer patients treated with 192Ir-based Venezia brachytherapy. Dose calculations were performed using RapidBrachyMCTPS, a Geant4-based research Monte Carlo treatment planning system. Ultimately, five dose calculation scenarios were evaluated: (a) dose to water in water (Dw,w); (b) Dw,w taking the applicator material into consideration (Dw,wApp); (c) dose to water in medium (Dw,m); (d and e) dose to medium in medium with mass densities assigned either nominally per structure (Dm,m (Nom)) or voxel-by-voxel (Dm,m). Results Ignoring the plastic Venezia applicator (Dw,wApp) overestimates Dm,m by up to 1% (average) with high energy source (192Ir and 75Se) and up to 2% with 169Yb. Scoring dose to water (Dw,wApp or Dw,m) generally overestimates dose and this effect increases with decreasing photon energy. Reporting dose other than Dm,m (or Dm,m Nom) for 169Yb-based conventional and intensity-modulated brachytherapy leads to a simultaneous overestimation (up to 4%) of CTVHR D90 and underestimation (up to 2%) of bladder D2cc due to a significant dip in the mass-energy absorption ratios at the depths of nearby targets and OARs. Using a nominal mass-density assignment per structure, rather than a CT-derived voxel-by-voxel assignment for MRI-guided brachytherapy, amounts to a dose error up to 1% for all radionuclides considered. Conclusions The effects of the considered dose reporting schemes trend correspondingly between conventional and intensity-modulated brachytherapy. In the absence of CT-derived mass densities, MRI-only-based dosimetry can adequately approximate Dm,m by assigning nominal mass densities to structures. Tissue and applicator heterogeneities do not significantly impact dosimetry for 192Ir and 75Se, but do for 169Yb; dose reporting must be explicitly defined since Dw,m and Dw,w may overstate the dosimetric benefits.
Morcos, Marc; Antaki, Majd; Viswanathan, Akila N.; Enger, Shirin A.
ESTRO Newsletter, 2021.
@misc{nokey,
title = {A novel, minimally invasive, dynamic‐shield, intensity‐modulated brachytherapy system for the treatment of cervical cancer. Editors’ pick.},
author = {Marc Morcos and Majd Antaki and Akila N. Viswanathan and Shirin A. Enger},
url = {https://www.estro.org/About/Newsroom/Newsletter/Brachytheraphy/A-novel,-minimally-invasive,-dynamic%E2%80%90shield,-inten },
year = {2021},
date = {2021-01-01},
howpublished = {ESTRO Newsletter},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
Morcos, Marc; Enger, Shirin A.
MR-guided intensity modulated brachytherapy for gynecologic cancers Presentation
McGill FMT, 01.01.2021.
@misc{Morcos2021,
title = {MR-guided intensity modulated brachytherapy for gynecologic cancers},
author = {Marc Morcos and Shirin A. Enger},
year = {2021},
date = {2021-01-01},
howpublished = {McGill FMT},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
2020
Famulari, Gabriel; Enger, Shirin A.
La curiethérapie avec modulation d’intensité par blindage dynamique pour le cancer de la prostate Presentation
Association Québécoise des Physiciens Médicaux Cliniques (AQPMC) Annual Meeting in QC, 02.11.2020.
@misc{Famulari2020b,
title = {La curiethérapie avec modulation d’intensité par blindage dynamique pour le cancer de la prostate},
author = {Gabriel Famulari and Shirin A. Enger},
year = {2020},
date = {2020-11-02},
howpublished = {Association Québécoise des Physiciens Médicaux Cliniques (AQPMC) Annual Meeting in QC},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Turgeon, Vincent; Morcos, Marc; Antaki, Majd; Enger, Shirin A.
Impact of choices in dosimetric calculation method for high dose rate brachytherapy of breast cancer Presentation
Radiotherapy and Oncology, 01.11.2020, ISSN: 0167-8140, 1879-0887.
@misc{Turgeon2020,
title = {Impact of choices in dosimetric calculation method for high dose rate brachytherapy of breast cancer},
author = {Vincent Turgeon and Marc Morcos and Majd Antaki and Shirin A. Enger},
url = {https://www.thegreenjournal.com/article/S0167-8140(21)01974-5/fulltext},
doi = {10.1016/S0167-8140(21)01974-5},
issn = {0167-8140, 1879-0887},
year = {2020},
date = {2020-11-01},
abstract = {www.thegreenjournal.com},
howpublished = {Radiotherapy and Oncology},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Famulari, Gabriel; Rosales, Haydee M. Linares; Dupere, Justine; Medich, David C.; Beaulieu, Luc; Enger, Shirin A.
In: Medical Physics, vol. 47, no. 9, pp. 4563–4573, 2020, ISSN: 2473-4209.
@article{famulari_monte_2020,
title = {Monte Carlo dosimetric characterization of a new high dose rate 169 Yb brachytherapy source and independent verification using a multipoint plastic scintillator detector},
author = {Gabriel Famulari and Haydee M. Linares Rosales and Justine Dupere and David C. Medich and Luc Beaulieu and Shirin A. Enger},
doi = {10.1002/mp.14336},
issn = {2473-4209},
year = {2020},
date = {2020-09-01},
journal = {Medical Physics},
volume = {47},
number = {9},
pages = {4563--4573},
abstract = {PURPOSE: A prototype 169 Yb source was developed in combination with a dynamic rotating platinum shield system (AIM-Brachy) to deliver intensity modulated brachytherapy (IMBT). The purpose of this study was to evaluate the dosimetric characteristics of the bare/shielded 169 Yb source using Monte Carlo (MC) simulations and perform an independent dose verification using a dosimetry platform based on a multipoint plastic scintillator detector (mPSD).
METHODS: The TG-43U1 dosimetric parameters were calculated for the source model using RapidBrachyMCTPS. Real-time dose rate measurements were performed in a water tank for both the bare/shielded source using a custom remote afterloader. For each dwell position, the dose rate was independently measured by the three scintillators (BCF-10, BCF-12, and BCF-60). For the bare source, dose rate was measured at distances up to 3 cm away from the source over a range of 7 cm along the catheter. For the shielded source, measurements were performed with the mPSD placed at 1 cm from the source at four different azimuthal angles ( 0 ∘ , 9 0 ∘ , 18 0 ∘ , and 27 0 ∘ ).
RESULTS: The dosimetric parameters were tabulated for the source model. For the bare source, differences between measured and calculated along-away dose rates were generally below 5-10%. Along the transverse axis, deviations were, on average (range), 3.3% (0.6-6.2%) for BCF-10, 1.7% (0.9-2.9%) for BCF-12, and 2.2% (0.3-4.4%) for BCF-60. The maximum dose rate reduction due to shielding at a radial distance of 1 cm was 88.8 ± 1.2%, compared to 83.5 ± 0.5% as calculated by MC.
CONCLUSIONS: The dose distribution for the bare/shielded 169 Yb source was independently verified using mPSD with good agreement in regions close to the source. The 169 Yb source coupled with the partial-shielding system is an effective technique to deliver IMBT.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
PURPOSE: A prototype 169 Yb source was developed in combination with a dynamic rotating platinum shield system (AIM-Brachy) to deliver intensity modulated brachytherapy (IMBT). The purpose of this study was to evaluate the dosimetric characteristics of the bare/shielded 169 Yb source using Monte Carlo (MC) simulations and perform an independent dose verification using a dosimetry platform based on a multipoint plastic scintillator detector (mPSD).
METHODS: The TG-43U1 dosimetric parameters were calculated for the source model using RapidBrachyMCTPS. Real-time dose rate measurements were performed in a water tank for both the bare/shielded source using a custom remote afterloader. For each dwell position, the dose rate was independently measured by the three scintillators (BCF-10, BCF-12, and BCF-60). For the bare source, dose rate was measured at distances up to 3 cm away from the source over a range of 7 cm along the catheter. For the shielded source, measurements were performed with the mPSD placed at 1 cm from the source at four different azimuthal angles ( 0 ∘ , 9 0 ∘ , 18 0 ∘ , and 27 0 ∘ ).
RESULTS: The dosimetric parameters were tabulated for the source model. For the bare source, differences between measured and calculated along-away dose rates were generally below 5-10%. Along the transverse axis, deviations were, on average (range), 3.3% (0.6-6.2%) for BCF-10, 1.7% (0.9-2.9%) for BCF-12, and 2.2% (0.3-4.4%) for BCF-60. The maximum dose rate reduction due to shielding at a radial distance of 1 cm was 88.8 ± 1.2%, compared to 83.5 ± 0.5% as calculated by MC.
CONCLUSIONS: The dose distribution for the bare/shielded 169 Yb source was independently verified using mPSD with good agreement in regions close to the source. The 169 Yb source coupled with the partial-shielding system is an effective technique to deliver IMBT.
METHODS: The TG-43U1 dosimetric parameters were calculated for the source model using RapidBrachyMCTPS. Real-time dose rate measurements were performed in a water tank for both the bare/shielded source using a custom remote afterloader. For each dwell position, the dose rate was independently measured by the three scintillators (BCF-10, BCF-12, and BCF-60). For the bare source, dose rate was measured at distances up to 3 cm away from the source over a range of 7 cm along the catheter. For the shielded source, measurements were performed with the mPSD placed at 1 cm from the source at four different azimuthal angles ( 0 ∘ , 9 0 ∘ , 18 0 ∘ , and 27 0 ∘ ).
RESULTS: The dosimetric parameters were tabulated for the source model. For the bare source, differences between measured and calculated along-away dose rates were generally below 5-10%. Along the transverse axis, deviations were, on average (range), 3.3% (0.6-6.2%) for BCF-10, 1.7% (0.9-2.9%) for BCF-12, and 2.2% (0.3-4.4%) for BCF-60. The maximum dose rate reduction due to shielding at a radial distance of 1 cm was 88.8 ± 1.2%, compared to 83.5 ± 0.5% as calculated by MC.
CONCLUSIONS: The dose distribution for the bare/shielded 169 Yb source was independently verified using mPSD with good agreement in regions close to the source. The 169 Yb source coupled with the partial-shielding system is an effective technique to deliver IMBT.