The influence of ionization chamber and phantom design on the measurement of lung dose in photon beams.
The influence of ionization chamber and phantom design on the measurement of lung dose in photon beams.
复制标题
电离室和体模设计对光子束肺剂量测量的影响。
DOI：
10.1118/1.596171
复制
发表时间：
1988
期刊：
影响因子：
3.8
通讯作者：
Bjärngard,BE
中科院分区：
文献类型：
--
作者：
Rice,RK;Hansen,JL;Chin,LM;Mijnheer,BJ;Bjärngard,BE
肺剂量校正因子，通常定义为电离室读数的比率在异质和同质幻影，已与那些基于准确确定的剂量进行了比较。阻止功率值的分析，Pwallvalues，并在lunglike和waterlike材料的测量结果表明，壁材料和厚度是不是非常关键的肺剂量校正因子的测定条件下的电子平衡。当由于低密度材料中散射电子的扩展范围而未建立横向电子平衡时，Prepl显著不同于具有与肺材料密度不匹配的厚壁的电离室的1。已经尝试将这种效应表征为光子能量、肺密度、射野大小和肺壁厚度的函数。
Lung dose correction factors, commonly defined as the ratios of ionization chamber readings in the heterogeneous and homogeneous phantoms, have been compared with those based on accurately determined doses. An analysis of stopping power values,Pwallvalues, and measurements in lunglike and waterlike materials showed that the wall material and thickness are not very critical in the determination of lung dose correction factors under conditions of electronic equilibrium. When lateral electronic equilibrium is not established due to the extended range of scattered electrons in the low density material,Prepldiffers significantly from unity for ionization chambers with thick walls which do not match the lung material in density. An attempt has been made to characterize this effect as a function of photon energy, lung density, field size, and wall thickness.