用能量沉积核函数方法计算^(60)Co照射野的吸收剂量

Dose calculation for ^(60)Co irradiation field using energy deposition kernels

目的 介绍了用能量沉积核函数方法计算60 Co照射野吸收剂量的方法。方法 能量沉积核函数方法将吸收剂量的贡献分为 3部分 :原射线、单次散射和多次散射。它使用基本的剂量学数据 ,如射野中心轴百分深度剂量、离轴比和准直系统散射输出因子等 ,这些数据在Fyc 5 0H治疗机上用方形照射野测量得到。再用能量沉积核函数计算吸收剂量。并讨论了散射线对吸收剂量的影响。结果 从测量数据得到了原射线和散射线的能量沉积核函数 ,并利用能量沉积核函数计算60 Co照射野的主要剂量学参数 ,计算值和测量值是一致的 ;不规则照射野的吸收剂量及其分布的计算结果也和测量结果符合得很好。结论 能量沉积核函数方法适用于较精确地计算60 Co不规则照射野的吸收剂量。

Objective\ A method for 60 Co dose calculation in radiotherapy using energy deposition kernels was presented. Methods\ The dose calculation for 60 Co irradiation field using energy deposition kernels separated the absorbed dose into three parts:the primary,single scatter and multiple scatter.It based on the basic beam data such as central axis percentage depth dose,off axis ratio and collimator scatter output factor,which were measured on Fyc 50H treatment unit for a number of square fields.The absorbed dose was calculated using the primary and scatter kernels.The absorbed dose due to scatter was also discussed. Results\ The primary and scatter kernels were deduced from the measured data.Characteristic parameters were then calculated using the primary and scatter kernels,the calculated and measured data were in good agreement.The absorbed dose and its distribution calculated for irregular field were satisfictorily matched with the measured data. Conclusion\ The method of using energy deposition kernels could be applied to accurate dose calculation for irregular 60 Co irradiation field in radiotherapy.