X(γ)刀剂量场的测量

Dosimetric measurements for X(γ)-knife beams

目的 :目前 ,国内X、γ刀的输出剂量及剂量分布尚无适宜的测量设备及相应的技术规范。由于X、γ刀剂量场的特点 ,不能用常规的电离室测量。本文的目的是为X、γ刀的剂量测量提供合理的设备和方法。材料与方法 :研制了灵敏区为 1mm的半导体探测器和体积为 0 .0 3cc的石墨电离室。用该探测器测量了γ刀在各种模体中的输出剂量及剂量分布。结果 :用研制的SCD -61半导体剂量仪和 0 .0 3cc石墨电离室测量了不同模体、不同准直器的输出剂量及剂量分布 ,根据对球形模的测量值 ,计算出各种射野时头形模的量分布 ,用热释光剂量仪做了验证 ,焦点值均在 5 %范围内一致。结论 :X、γ刀的输出剂量及剂量分布应在现场进行实际测量 ,所用探头直径应小于射野直径的一半。灵敏区～ 1mm的半导体探测器适合作X。

Purpose: There is no appropriate instrument or devices and corresponding technological specification for measurement of output dose and dose disdribution in stereotactic radiothrapy. Small field of the stereotatic radiotherapy can't be measured by normal ionization chamber for its characteristics.A practible instrument and method were developed for dose measurement in stereotactic irradiation.Materials and Methods:A diode detector with 1mm sensitivety volume and a 0.3cc graphite chamber developed by us are used to measure the dose output & dose distribution in warious phantom for the beams used in stereotactic irradiation.Results:The dose outputs and dose ditributions measured by SCD-61 diode developed by us were tested and verified by TLD dosemeter,and the results show tha there is a 5% consistency for the value at the focus point.Conclusion: the diameter of the detector used for measurement must be smaller than the halt size of the radiation beams to be measured. A diode detector with 1mm sensitivity volume is the best choice for the dosimetric measurements for smaller beams used in stereotactic irradiation.