Transit dose calculation in high dose rate brachytherapy (HDR) using Sievert integral

Abstract

Transit doses around a high dose rate ¹⁹²Ir brachytherapy source were calculated using Sievert Integral at positions where the moving source was located exactly between two adjacent dwell positions. The correspond-ing transit dose rates were obtained by using energy absorption coefficients. Discrete step sizes of 0.25 cm were chosen to calculate the dose rates and total transit doses at selected points. A linear implant was used as an example and the maximum values of the transit dose obtained at standard prescription distances of 1 and 2 cm along the perpendicular bisector of the implant were 0.60 and 1.81 cGy, respectively. Any discrepancy between the results obtained from Sievert Integral and other published data did not contribute significantly to the bulk of the dose prescribed under any clinical situation. The Sievert Integral is therefore an effective formalism for evaluating transit doses in HDR brachytherapy.

Journal of Applied Science and Technology Vol. 10(1&2) 2005: 80-84