摘要
目的:美国医学物理学家协会(AAPM)TG-51协议和国际原子能结构(IAEA)TRS-398报告分别提出基于水模体吸收剂量校准因子N60CoD,w及ND,w,Q0的吸收剂量测定规程,而我国至今没有相应的测定规程。计算三种常用进口指形电离室的N60CoD,w/NX和ND,w,Q0/NX值,分别为CapintecPR-06C、NE2571及PTW30001,以便用国家计量实验室给出的照射量校准因子NX获得N60CoD,w及ND,w,Q0。方法:根据TG-21和TG-51号协议推导出N60CoD,w/NX;根据IAEATRS-277及398号报告推导出ND,w,Q0/NX。结果:CapintecPR-06C的N60CoD,w/NX和ND,w,Q0/NX值分别为0.949和0.960,单位10-2Gy/R;NE2571,0.956和0.957;PTW30001,0.954和0.956。结论:ND,w,Q0的理论值有可能比N60CoD,w的更准确;不同指形电离室的N60CoD,w和ND,w,Q0的理论值变化并不显著。
Objective： The TG-51 protocol of the American Association of Physicists in Medicine uses ion chambers with absorbed-dose-to water calibration factor, ND,w^60Co. Similarly, TRS-398 of the International Atomic Energy Agency requires calibration factor in term of absorbed dose to water for dosimeter, ND,w,Q0. There is no analogical protocol or code in China. We compute the ND,w^60Co/NX and ND,w,Q0/NX ratios for three ion chambers, Capintec PR-06C, NE2571 and PTW 30001, in order to indirectly get ND,w^60Co or ND,w,Q0, for the National Standard Dosimetry Laboratory can only provide exposure calibration factor,Nx. Methods： The ND,w^60Co ratios are formulated according to the TG-21 and TG-51 protocols and the ND,w,Q0/NX ratios are acquired on the basis of TRS-277 and TRS-398. Results： The values of ND,w^60Co/NX and ND,w,Q0/NX ratios for Capintec PR-06C are 0.949 and 0.960, unit 10-2Gy/R; NE2571, 0.956 and 957; PTW 30001; 0.954 and 0.956, respectively. Conclusions： The theoretical value of ND,w,Q0 is more precise than that of ND,w^60Co The theoretical values of ND,w^60Co and ND,w,Q0/NX for different Farmer chambers vary in a narrow range.
出处
《中国医学物理学杂志》
CSCD
2009年第4期1270-1272,共3页
Chinese Journal of Medical Physics
关键词
水模体吸收剂量校准因子
照射量校准因子
电离室
calibration factor in term of absorbed dose to water
exposure calibration factor
ion chamber
