TY - JOUR
T1 - Monte Carlo aided dosimetry of the microselectron pulsed and high dose-rate lr sources
AU - Williamson, Jeffrey F.
AU - Li, Zuofena
PY - 1995/6
Y1 - 1995/6
N2 - Despite the large number of single-stepping source pulsed and high dose-rate (HDR) remote after-loading devices in clinical use, the published literature contain little data characterizing dose-rate distributions around the high-intensity (4×103-4×104μGy m2h−1) 192Ir sources currently used in these devices. We have used the Monte Carlo method to calculate complete two-dimensional dose-rate distributions about the most widely used high dose-rate source design, as well as the Nucletron pulsed dose-rate (PDR) Ir source. A Monte Carlo photon transport code, incorporating the detailed internal geometry of the source, was used to calculate the dose rate per unit air-kerma strength in water medium on the transverse bisecting axis over the 0.15-12 cm distance range. In addition, polar dose profiles were calculated at distances ranging from 0.25 to 5 cm. The PDR and HDR dose-rate distributions are tabulated using the formalism endorsed by the Interstitial Collaborative Working Group and the AAPM Task Group 43, and includes dose-rate constant, radial dose function, anisotropy function, geometry function, and anisotropy factors. The dose-rate constants, A, of the MicroSelectron/HDR and PDR sources were found to be 1.115 and 1.128 cGyh−1per unit air-kerma strength, respectively, in good agreement with previously published data for low dose-rate interstitial Ir sources. Oblique filtration by the high-density iridium metal core resulted in deviations from anisotropy as large as 35%-55% near the longitudinal axis of the source. Dose-rate distributions are also presented in Cartesian (“away” and “along”) coordinates.
AB - Despite the large number of single-stepping source pulsed and high dose-rate (HDR) remote after-loading devices in clinical use, the published literature contain little data characterizing dose-rate distributions around the high-intensity (4×103-4×104μGy m2h−1) 192Ir sources currently used in these devices. We have used the Monte Carlo method to calculate complete two-dimensional dose-rate distributions about the most widely used high dose-rate source design, as well as the Nucletron pulsed dose-rate (PDR) Ir source. A Monte Carlo photon transport code, incorporating the detailed internal geometry of the source, was used to calculate the dose rate per unit air-kerma strength in water medium on the transverse bisecting axis over the 0.15-12 cm distance range. In addition, polar dose profiles were calculated at distances ranging from 0.25 to 5 cm. The PDR and HDR dose-rate distributions are tabulated using the formalism endorsed by the Interstitial Collaborative Working Group and the AAPM Task Group 43, and includes dose-rate constant, radial dose function, anisotropy function, geometry function, and anisotropy factors. The dose-rate constants, A, of the MicroSelectron/HDR and PDR sources were found to be 1.115 and 1.128 cGyh−1per unit air-kerma strength, respectively, in good agreement with previously published data for low dose-rate interstitial Ir sources. Oblique filtration by the high-density iridium metal core resulted in deviations from anisotropy as large as 35%-55% near the longitudinal axis of the source. Dose-rate distributions are also presented in Cartesian (“away” and “along”) coordinates.
KW - Carlo simulation
KW - Ir
KW - Monte
KW - high dose-rate brachytherapy
KW - pulsed dose-rate brachytherapy dosimetry
UR - http://www.scopus.com/inward/record.url?scp=0029038383&partnerID=8YFLogxK
U2 - 10.1118/1.597483
DO - 10.1118/1.597483
M3 - Article
C2 - 7565372
AN - SCOPUS:0029038383
SN - 0094-2405
VL - 22
SP - 809
EP - 819
JO - Medical physics
JF - Medical physics
IS - 6
ER -