Journal Articles
2016
Quast, Ulrich; Kaulich, Theodor W.; Álvarez-Romero, José T.; Tedgren, Sa Carlsson; Enger, Shirin A.; Medich, David C.; Mourtada, Firas; Perez-Calatayud, Jose; Rivard, Mark J.; Zakaria, G. Abu
A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry Journal Article
In: Physica medica: PM: an international journal devoted to the applications of physics to medicine and biology: official journal of the Italian Association of Biomedical Physics (AIFB), vol. 32, no. 6, pp. 741–748, 2016, ISSN: 1724-191X.
Abstract | Links | BibTeX | Tags: Absorbed dose to water, Brachytherapy, Detector response, Effective energy, Photon brachytherapy radiation quality index, Photons, Radiation, Radiometry, Scattering, Uncertainty
@article{quast_brachytherapy_2016,
title = {A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry},
author = {Ulrich Quast and Theodor W. Kaulich and José T. Álvarez-Romero and Sa Carlsson Tedgren and Shirin A. Enger and David C. Medich and Firas Mourtada and Jose Perez-Calatayud and Mark J. Rivard and G. Abu Zakaria},
doi = {10.1016/j.ejmp.2016.03.008},
issn = {1724-191X},
year = {2016},
date = {2016-06-01},
journal = {Physica medica: PM: an international journal devoted to the applications of physics to medicine and biology: official journal of the Italian Association of Biomedical Physics (AIFB)},
volume = {32},
number = {6},
pages = {741--748},
abstract = {INTRODUCTION: In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector's response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. MATERIALS AND METHODS: While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. RESULTS AND DISCUSSION: For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector's response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources.
CONCLUSIONS: This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon's penetration probability and scattering potential.},
keywords = {Absorbed dose to water, Brachytherapy, Detector response, Effective energy, Photon brachytherapy radiation quality index, Photons, Radiation, Radiometry, Scattering, Uncertainty},
pubstate = {published},
tppubtype = {article}
}
INTRODUCTION: In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector’s response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. MATERIALS AND METHODS: While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. RESULTS AND DISCUSSION: For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector’s response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources.
CONCLUSIONS: This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon’s penetration probability and scattering potential.2013
Enger, Shirin A.; Fisher, Darrell R.; Flynn, Ryan T.
Gadolinium-153 as a brachytherapy isotope Journal Article
In: Physics in Medicine and Biology, vol. 58, no. 4, pp. 957–964, 2013, ISSN: 1361-6560.
Abstract | Links | BibTeX | Tags: Anisotropy, Brachytherapy, Equipment Design, Gadolinium, Humans, Iridium Radioisotopes, Male, Monte Carlo Method, Photons, Prostatic Neoplasms, Radiation, Radiation Protection, Radioisotopes, Radiotherapy Dosage, Scattering
@article{enger_gadolinium-153_2013,
title = {Gadolinium-153 as a brachytherapy isotope},
author = {Shirin A. Enger and Darrell R. Fisher and Ryan T. Flynn},
doi = {10.1088/0031-9155/58/4/957},
issn = {1361-6560},
year = {2013},
date = {2013-02-01},
journal = {Physics in Medicine and Biology},
volume = {58},
number = {4},
pages = {957--964},
abstract = {The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir.},
keywords = {Anisotropy, Brachytherapy, Equipment Design, Gadolinium, Humans, Iridium Radioisotopes, Male, Monte Carlo Method, Photons, Prostatic Neoplasms, Radiation, Radiation Protection, Radioisotopes, Radiotherapy Dosage, Scattering},
pubstate = {published},
tppubtype = {article}
}
The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir.2012
Enger, Shirin A.; Lundqvist, Hans; D’Amours, Michel; Beaulieu, Luc
Exploring (57)Co as a new isotope for brachytherapy applications Journal Article
In: Medical Physics, vol. 39, no. 5, pp. 2342–2345, 2012, ISSN: 0094-2405.
Abstract | Links | BibTeX | Tags: Anisotropy, Brachytherapy, Cobalt Radioisotopes, Monte Carlo Method, Radiation, Radiometry, Scattering
@article{enger_exploring_2012,
title = {Exploring (57)Co as a new isotope for brachytherapy applications},
author = {Shirin A. Enger and Hans Lundqvist and Michel D'Amours and Luc Beaulieu},
doi = {10.1118/1.3700171},
issn = {0094-2405},
year = {2012},
date = {2012-05-01},
journal = {Medical Physics},
volume = {39},
number = {5},
pages = {2342--2345},
abstract = {PURPOSE: The characteristics of the radionuclide (57)Co make it interesting for use as a brachytherapy source. (57)Co combines a possible high specific activity with the emission of relatively low-energy photons and a half-life (272 days) suitable for regular source exchanges in an afterloader. (57)Co decays by electron capture to the stable (57)Fe with emission of 136 and 122 keV photons.
METHODS: A hypothetical (57)Co source based on the Flexisource brachytherapy encapsulation with the active core set as a pure cobalt cylinder (length 3.5 mm and diameter 0.6 mm) covered with a cylindrical stainless-steel capsule (length 5 mm and thickness 0.125 mm) was simulated using Geant4 Monte Carlo (MC) code version 9.4. The radial dose function, g(r), and anisotropy function F(r,θ), for the line source approximation were calculated following the TG-43U1 formalism. The results were compared to well-known (192)Ir and (125)I radionuclides, representing the higher and the lower energy end of brachytherapy, respectively.
RESULTS: The mean energy of photons in water, after passing through the core and the encapsulation material was 123 keV. This hypothetical (57)Co source has an increasing g(r) due to multiple scatter of low-energy photons, which results in a more uniform dose distribution than (192)Ir.
CONCLUSIONS: (57)Co has many advantages compared to (192)Ir due to its low-energy gamma emissions without any electron contamination. (57)Co has an increasing g(r) that results in a more uniform dose distribution than (192)Ir due to its multiple scattered photons. The anisotropy of the (57)Co source is comparable to that of (192)Ir. Furthermore, (57)Co has lower shielding requirements than (192)Ir.},
keywords = {Anisotropy, Brachytherapy, Cobalt Radioisotopes, Monte Carlo Method, Radiation, Radiometry, Scattering},
pubstate = {published},
tppubtype = {article}
}
PURPOSE: The characteristics of the radionuclide (57)Co make it interesting for use as a brachytherapy source. (57)Co combines a possible high specific activity with the emission of relatively low-energy photons and a half-life (272 days) suitable for regular source exchanges in an afterloader. (57)Co decays by electron capture to the stable (57)Fe with emission of 136 and 122 keV photons.
METHODS: A hypothetical (57)Co source based on the Flexisource brachytherapy encapsulation with the active core set as a pure cobalt cylinder (length 3.5 mm and diameter 0.6 mm) covered with a cylindrical stainless-steel capsule (length 5 mm and thickness 0.125 mm) was simulated using Geant4 Monte Carlo (MC) code version 9.4. The radial dose function, g(r), and anisotropy function F(r,θ), for the line source approximation were calculated following the TG-43U1 formalism. The results were compared to well-known (192)Ir and (125)I radionuclides, representing the higher and the lower energy end of brachytherapy, respectively.
RESULTS: The mean energy of photons in water, after passing through the core and the encapsulation material was 123 keV. This hypothetical (57)Co source has an increasing g(r) due to multiple scatter of low-energy photons, which results in a more uniform dose distribution than (192)Ir.
CONCLUSIONS: (57)Co has many advantages compared to (192)Ir due to its low-energy gamma emissions without any electron contamination. (57)Co has an increasing g(r) that results in a more uniform dose distribution than (192)Ir due to its multiple scattered photons. The anisotropy of the (57)Co source is comparable to that of (192)Ir. Furthermore, (57)Co has lower shielding requirements than (192)Ir.
Journal Articles
2016
Quast, Ulrich; Kaulich, Theodor W.; Álvarez-Romero, José T.; Tedgren, Sa Carlsson; Enger, Shirin A.; Medich, David C.; Mourtada, Firas; Perez-Calatayud, Jose; Rivard, Mark J.; Zakaria, G. Abu
A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry Journal Article
In: Physica medica: PM: an international journal devoted to the applications of physics to medicine and biology: official journal of the Italian Association of Biomedical Physics (AIFB), vol. 32, no. 6, pp. 741–748, 2016, ISSN: 1724-191X.
Abstract | Links | BibTeX | Tags: Absorbed dose to water, Brachytherapy, Detector response, Effective energy, Photon brachytherapy radiation quality index, Photons, Radiation, Radiometry, Scattering, Uncertainty
@article{quast_brachytherapy_2016,
title = {A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry},
author = {Ulrich Quast and Theodor W. Kaulich and José T. Álvarez-Romero and Sa Carlsson Tedgren and Shirin A. Enger and David C. Medich and Firas Mourtada and Jose Perez-Calatayud and Mark J. Rivard and G. Abu Zakaria},
doi = {10.1016/j.ejmp.2016.03.008},
issn = {1724-191X},
year = {2016},
date = {2016-06-01},
journal = {Physica medica: PM: an international journal devoted to the applications of physics to medicine and biology: official journal of the Italian Association of Biomedical Physics (AIFB)},
volume = {32},
number = {6},
pages = {741--748},
abstract = {INTRODUCTION: In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector's response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. MATERIALS AND METHODS: While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. RESULTS AND DISCUSSION: For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector's response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources.
CONCLUSIONS: This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon's penetration probability and scattering potential.},
keywords = {Absorbed dose to water, Brachytherapy, Detector response, Effective energy, Photon brachytherapy radiation quality index, Photons, Radiation, Radiometry, Scattering, Uncertainty},
pubstate = {published},
tppubtype = {article}
}
INTRODUCTION: In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector’s response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. MATERIALS AND METHODS: While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. RESULTS AND DISCUSSION: For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector’s response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources.
CONCLUSIONS: This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon’s penetration probability and scattering potential.
CONCLUSIONS: This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon’s penetration probability and scattering potential.
2013
Enger, Shirin A.; Fisher, Darrell R.; Flynn, Ryan T.
Gadolinium-153 as a brachytherapy isotope Journal Article
In: Physics in Medicine and Biology, vol. 58, no. 4, pp. 957–964, 2013, ISSN: 1361-6560.
Abstract | Links | BibTeX | Tags: Anisotropy, Brachytherapy, Equipment Design, Gadolinium, Humans, Iridium Radioisotopes, Male, Monte Carlo Method, Photons, Prostatic Neoplasms, Radiation, Radiation Protection, Radioisotopes, Radiotherapy Dosage, Scattering
@article{enger_gadolinium-153_2013,
title = {Gadolinium-153 as a brachytherapy isotope},
author = {Shirin A. Enger and Darrell R. Fisher and Ryan T. Flynn},
doi = {10.1088/0031-9155/58/4/957},
issn = {1361-6560},
year = {2013},
date = {2013-02-01},
journal = {Physics in Medicine and Biology},
volume = {58},
number = {4},
pages = {957--964},
abstract = {The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir.},
keywords = {Anisotropy, Brachytherapy, Equipment Design, Gadolinium, Humans, Iridium Radioisotopes, Male, Monte Carlo Method, Photons, Prostatic Neoplasms, Radiation, Radiation Protection, Radioisotopes, Radiotherapy Dosage, Scattering},
pubstate = {published},
tppubtype = {article}
}
The purpose of this work was to present the fundamental dosimetric characteristics of a hypothetical (153)Gd brachytherapy source using the AAPM TG-43U1 dose-calculation formalism. Gadolinium-153 is an intermediate-energy isotope that emits 40-100 keV photons with a half-life of 242 days. The rationale for considering (153)Gd as a brachytherapy source is for its potential of patient specific shielding and to enable reduced personnel shielding requirements relative to (192)Ir, and as an isotope for interstitial rotating shield brachytherapy (I-RSBT). A hypothetical (153)Gd brachytherapy source with an active core of 0.84 mm diameter, 10 mm length and specific activity of 5.55 TBq of (153)Gd per gram of Gd was simulated with Geant4. The encapsulation material was stainless steel with a thickness of 0.08 mm. The radial dose function, anisotropy function and photon spectrum in water were calculated for the (153)Gd source. The simulated (153)Gd source had an activity of 242 GBq and a dose rate in water 1 cm off axis of 13.12 Gy h(-1), indicating that it would be suitable as a low-dose-rate or pulsed-dose-rate brachytherapy source. The beta particles emitted have low enough energies to be absorbed in the source encapsulation. Gadolinium-153 has an increasing radial dose function due to multiple scatter of low-energy photons. Scattered photon dose takes over with distance from the source and contributes to the majority of the absorbed dose. The anisotropy function of the (153)Gd source decreases at low polar angles, as a result of the long active core. The source is less anisotropic at polar angles away from the longitudinal axes. The anisotropy function increases with increasing distance. The (153)Gd source considered would be suitable as an intermediate-energy low-dose-rate or pulsed-dose-rate brachytherapy source. The source could provide a means for I-RSBT delivery and enable brachytherapy treatments with patient specific shielding and reduced personnel shielding requirements relative to (192)Ir.
2012
Enger, Shirin A.; Lundqvist, Hans; D’Amours, Michel; Beaulieu, Luc
Exploring (57)Co as a new isotope for brachytherapy applications Journal Article
In: Medical Physics, vol. 39, no. 5, pp. 2342–2345, 2012, ISSN: 0094-2405.
Abstract | Links | BibTeX | Tags: Anisotropy, Brachytherapy, Cobalt Radioisotopes, Monte Carlo Method, Radiation, Radiometry, Scattering
@article{enger_exploring_2012,
title = {Exploring (57)Co as a new isotope for brachytherapy applications},
author = {Shirin A. Enger and Hans Lundqvist and Michel D'Amours and Luc Beaulieu},
doi = {10.1118/1.3700171},
issn = {0094-2405},
year = {2012},
date = {2012-05-01},
journal = {Medical Physics},
volume = {39},
number = {5},
pages = {2342--2345},
abstract = {PURPOSE: The characteristics of the radionuclide (57)Co make it interesting for use as a brachytherapy source. (57)Co combines a possible high specific activity with the emission of relatively low-energy photons and a half-life (272 days) suitable for regular source exchanges in an afterloader. (57)Co decays by electron capture to the stable (57)Fe with emission of 136 and 122 keV photons.
METHODS: A hypothetical (57)Co source based on the Flexisource brachytherapy encapsulation with the active core set as a pure cobalt cylinder (length 3.5 mm and diameter 0.6 mm) covered with a cylindrical stainless-steel capsule (length 5 mm and thickness 0.125 mm) was simulated using Geant4 Monte Carlo (MC) code version 9.4. The radial dose function, g(r), and anisotropy function F(r,θ), for the line source approximation were calculated following the TG-43U1 formalism. The results were compared to well-known (192)Ir and (125)I radionuclides, representing the higher and the lower energy end of brachytherapy, respectively.
RESULTS: The mean energy of photons in water, after passing through the core and the encapsulation material was 123 keV. This hypothetical (57)Co source has an increasing g(r) due to multiple scatter of low-energy photons, which results in a more uniform dose distribution than (192)Ir.
CONCLUSIONS: (57)Co has many advantages compared to (192)Ir due to its low-energy gamma emissions without any electron contamination. (57)Co has an increasing g(r) that results in a more uniform dose distribution than (192)Ir due to its multiple scattered photons. The anisotropy of the (57)Co source is comparable to that of (192)Ir. Furthermore, (57)Co has lower shielding requirements than (192)Ir.},
keywords = {Anisotropy, Brachytherapy, Cobalt Radioisotopes, Monte Carlo Method, Radiation, Radiometry, Scattering},
pubstate = {published},
tppubtype = {article}
}
PURPOSE: The characteristics of the radionuclide (57)Co make it interesting for use as a brachytherapy source. (57)Co combines a possible high specific activity with the emission of relatively low-energy photons and a half-life (272 days) suitable for regular source exchanges in an afterloader. (57)Co decays by electron capture to the stable (57)Fe with emission of 136 and 122 keV photons.
METHODS: A hypothetical (57)Co source based on the Flexisource brachytherapy encapsulation with the active core set as a pure cobalt cylinder (length 3.5 mm and diameter 0.6 mm) covered with a cylindrical stainless-steel capsule (length 5 mm and thickness 0.125 mm) was simulated using Geant4 Monte Carlo (MC) code version 9.4. The radial dose function, g(r), and anisotropy function F(r,θ), for the line source approximation were calculated following the TG-43U1 formalism. The results were compared to well-known (192)Ir and (125)I radionuclides, representing the higher and the lower energy end of brachytherapy, respectively.
RESULTS: The mean energy of photons in water, after passing through the core and the encapsulation material was 123 keV. This hypothetical (57)Co source has an increasing g(r) due to multiple scatter of low-energy photons, which results in a more uniform dose distribution than (192)Ir.
CONCLUSIONS: (57)Co has many advantages compared to (192)Ir due to its low-energy gamma emissions without any electron contamination. (57)Co has an increasing g(r) that results in a more uniform dose distribution than (192)Ir due to its multiple scattered photons. The anisotropy of the (57)Co source is comparable to that of (192)Ir. Furthermore, (57)Co has lower shielding requirements than (192)Ir.
METHODS: A hypothetical (57)Co source based on the Flexisource brachytherapy encapsulation with the active core set as a pure cobalt cylinder (length 3.5 mm and diameter 0.6 mm) covered with a cylindrical stainless-steel capsule (length 5 mm and thickness 0.125 mm) was simulated using Geant4 Monte Carlo (MC) code version 9.4. The radial dose function, g(r), and anisotropy function F(r,θ), for the line source approximation were calculated following the TG-43U1 formalism. The results were compared to well-known (192)Ir and (125)I radionuclides, representing the higher and the lower energy end of brachytherapy, respectively.
RESULTS: The mean energy of photons in water, after passing through the core and the encapsulation material was 123 keV. This hypothetical (57)Co source has an increasing g(r) due to multiple scatter of low-energy photons, which results in a more uniform dose distribution than (192)Ir.
CONCLUSIONS: (57)Co has many advantages compared to (192)Ir due to its low-energy gamma emissions without any electron contamination. (57)Co has an increasing g(r) that results in a more uniform dose distribution than (192)Ir due to its multiple scattered photons. The anisotropy of the (57)Co source is comparable to that of (192)Ir. Furthermore, (57)Co has lower shielding requirements than (192)Ir.