半野照射技术剂量计算的优化研究

Optimization study on clinical dose calculation in semi-field irradiation

目的:探讨半野照射中利用修正因子修正常用剂量计算公式,提高半野照射剂量计算准确性。方法:使用带有独立准直器的直线加速器实施不同等效边长照射野的半野照射,比较半野照射剂量计算值与实测值,并通过数据拟合得出修正因子随等效边长的数学关系。结果:修正因子随面积增加而增大,存在一定数学关系;经修正后剂量计算值与实测值更接近,准确度比常用临床剂量计划系统更高。结论:半野修正因子可以简便地优化剂量计算,提高了半野照射剂量计算的准确性。

Objective： A correction factor was proposed to improve the accuracy of dose calculation in conventional radiotherapy when filed matching technique was used. Methods： Use the linear accelerator with independent collimator to implement semi-field irradiation under different equivalent-length field. Measure the dose and compare it with the calculation dose. Obtain a correction factor which change follow the equivalent-length through data fitting. Results： There is relationship to indicate the correction factor increase if the field area enlarge; the calculation dose will be close to the measure dose, and the accuracy will improve by correcting; Conclusion： The clinical dose of semi-field irradiation can be calculated by an equivalent square field technique, and then multiplied by the correction factor. it is a simplemethod to improve the accuracy of dose calculation in conventional radiotherapy by using semi-filed correction factor when filed matching technique was used.