TY - JOUR

T1 - Monte Carlo evaluation of the Sievert integral for brachytherapy dosimetry

AU - Williamson, J. F.

AU - Morin, R. L.

AU - Khan, F. M.

PY - 1983

Y1 - 1983

N2 - The Sievert integral, widely used to compute dose distributions about filtered line sources, assumes that the emitted energy fluence if exponentially attenuated by the filter thickness traversed by the primary photons. To evaluate this approximation, a Monte Carlo simulation was performed realistically modelling the diffusion and energy degradation of primary photons due to coherent, incoherent and photoelectric interactions in the source filter. Estimates of the exposure rate at points near the source were obtained using analytical averaging. Comparison of the two models shows that for 226Ra and 192Ir sources, the Sievert algorithm consistently overestimates the exposure rate per unit activity. However, such errors may be significantly reduced if source intensity is expressed in terms of exposure rate. Computed exposure rate distributions based on exposure rate calibrations are also less sensitive to uncertainties in available spectroscopic data.

AB - The Sievert integral, widely used to compute dose distributions about filtered line sources, assumes that the emitted energy fluence if exponentially attenuated by the filter thickness traversed by the primary photons. To evaluate this approximation, a Monte Carlo simulation was performed realistically modelling the diffusion and energy degradation of primary photons due to coherent, incoherent and photoelectric interactions in the source filter. Estimates of the exposure rate at points near the source were obtained using analytical averaging. Comparison of the two models shows that for 226Ra and 192Ir sources, the Sievert algorithm consistently overestimates the exposure rate per unit activity. However, such errors may be significantly reduced if source intensity is expressed in terms of exposure rate. Computed exposure rate distributions based on exposure rate calibrations are also less sensitive to uncertainties in available spectroscopic data.

UR - http://www.scopus.com/inward/record.url?scp=0020592244&partnerID=8YFLogxK

U2 - 10.1088/0031-9155/28/9/002

DO - 10.1088/0031-9155/28/9/002

M3 - Article

C2 - 6634938

AN - SCOPUS:0020592244

VL - 28

SP - 1021

EP - 1032

JO - Physics in Medicine and Biology

JF - Physics in Medicine and Biology

SN - 0031-9155

IS - 9

M1 - 002

ER -