论文部分内容阅读
目的 比较直接查表法、有效面积周长比法、Day氏法、Clarkson法在计算不规则照射野中心轴百分深度剂量(PDD)中的准确性和简易性。方法 用60 Co γ射线在源皮距 (SSD =75cm)条件下对不同面积的不规则照射野进行照射 ,采用上述方法分别计算特定深度处的PDD。结果 以Clarkson法作为标准 ,直接查表法相对误差范围为 0 .32 %～ 2 .76 % ,有效面积周长比法相对误差范围为 -0 .75 %～ 0 .47% ,Day氏法相对误差范围为 -1.2 7%～ -0 .0 8%。结论 有效面积周长比法在一般边角挡铅的不规则照射野中心轴PDD计算中 ,相对误差平均为 -0 .0 8% ,误差范围在± 1%以内 ,精确程度高 ,而且使用方便
Objective To compare the accuracy and simplicity of direct table lookup, effective area perimeter method, Day’s method and Clarkson method in calculating PDD of irregularly exposed fields. Methods Irradiation with different areas was irradiated with 60 Co γ-rays at the source skin distance (SSD = 75 cm). PDDs at specific depths were calculated using the above method. Results The Clarkson method was used as the standard. The relative error range of direct lookup table method was 0.32% -2.76%, and the relative error range of effective area perimeter ratio method was -0.75% -0.47% The error range is -1.2 7% -0.0 8%. Conclusions The effective area perimeter ratio method has the average relative error of -0.08% and the error range of ± 1% within the PDD calculation of the irregular radiation fields in the general corner block with high accuracy and easy to use