VARIAN 23ex小照射野剂量测量方法研究

Study on the Small Field Dosimetry of VARIAN 23ex

目的对于调强放射治疗尤其是立体放射治疗,小照射野的建模数据尤其重要;VARIAN直线加速器23ex在数据建模是并未考虑到小照射野剂量学的问题,因此小射野放射治疗中缺少了数据支持。方法本研究通过测量加速器6MV条件下小照射野数据,并计算射野总散射因子Scp,并对结果进行处理分析。结果测量机器出束100MU半导体探头、胶片剂量仪测得的点剂量与尚未小野建模计划系统计算相同深度的点剂量比较,差异明显(最大误差分别为-2.7%、12%)。结论对于小照射野,测量电子平衡不能建立,不同的测量探头,对小野的物理数据测量的准确性可能存在很大差异。

Objective For intensity modulated radiation therapy(IMRT),especially stereo radiation therapy(STRT),the modeling data of small field are particularly important.The data modeling of VARIAN linear accelerator 23 ex used in our department did not take the dosimetry of small field into account,so there was no data support in small field radiotherapy.Methods The total scattering factor Scp was calculated by measuring the data of the small field under the condition of 6 MV accelerator,and the results were processed and analyzed.Results The point dose measured by the 100 MU semiconductor probe and film dosimeter of the machine beam exit was significantly different from that calculated by the Oeno Modeling Planning System at the same depth(the maximum error was-2.7%and 12%,respectively).Conclusion For small field,the measurement of electronic balance can not be established.The accuracy of measurement of physical data of small field may vary greatly with different measuring probes.