Monte Carlo-based Spencer-Attix and Bragg-Gray tissue-to-air stopping power ratios for ISO beta sources

被引：8

作者：

Selvam, T. Palani ^{[1
]}

Vandana, S. ^{[1
]}

Bakshi, A. K. ^{[1
]}

Babu, D. A. R. ^{[1
]}

机构：

[1] Bhabha Atom Res Ctr, Hlth Safety & Environm Grp, Radiol Phys & Advisory Div, Bombay 400085, Maharashtra, India

来源：

RADIATION PROTECTION DOSIMETRY | 2016年 / 168卷 / 02期

关键词：

CAVITY IONIZATION;

D O I：

10.1093/rpd/ncv283

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

Spencer-Attix (SA) and Bragg-Gray (BG) mass-collision-stopping-power ratios of tissue-to-air are calculated using a modified version of EGSnrc-based SPRRZnrc user-code for the International Organization for Standardization (ISO) beta sources such as Pm-147, Kr-85, Sr-90/Y-90 and Ru-106/Rh-106. The ratios are calculated at 5 and 70 A mu m depths along the central axis of the unit density ICRU-4-element tissue phantom as a function of air-cavity lengths of the extrapolation chamber l = 0.025-0.25 cm. The study shows that the BG values are independent of l and agree well with the ISO-reported values for the above sources. The overall variation in the SA values is similar to 0.3 % for all the investigated sources, when l is varied from 0.025 to 0.25 cm. As energy of the beta increases the SA stopping-power ratio for a given cavity length decreases. For example, SA values of Pm-147 are higher by similar to 2 % when compared with the corresponding values of Ru-106/Rh-106 source. SA stopping-power ratios are higher than the BG stopping-power ratios and the degree of variation depends on type of source and the value of l. For example, the difference is up to 0.7 % at l = 0.025 cm for the Sr-90/Y-90 source.

引用

页码：184 / 189

页数：6