【摘要】 目的　选择一种能准确适用于临床应用的电子线矩形野与方野输出因子的换算方法。方法　使用 6、12、15MeV电子线 ,国产TL30 0 0C剂量仪 ,0 .6cm3 电离室探头 ;采用源皮距 (SSD)方法测量。比较 3个不同输出因子转换理论公式的计算值与实际测量值的符合程度。结果　理论公式OUF(X ,Y) =[OUF(X ,X) ·OUF(Y ,Y) ]1/ 2 计算值与实际测量值符合较好 ,较大野时理论计算值与实际值更符合。结论　对于边长大于射程的矩形野 ,其输出因子可以由理论公式较精确地计算 ,它是适合于临床应用的计算方法。更多还原

【Abstract】 Objective A simple and accurate calculation method was designed to convert output factor from square field into rectangular field in electron beam, which can be easily implemented in clinical practice. Methods 6, 12, 15?MeV electron beam, field size 6.0?cm×7.5?cm, 5.0?cm×10.0?cm, 6.0?cm×12.0?cm, TL3000C dosimeter and source to surface distance method were used in dose measurement. The measured dose values were compared with the calculated ones from three theoretical equations with the conformation evaluated. Results The calculated dose values from three theoretical equations differed from the measured ones by 0.23%, 1.30% and 1.10% (6?MeV), 0.63%, 0.90% and 0.73% (12?MeV), 0.50%, 1.80% and 3.40% (15?MeV), conforming best to the equation OUF(X,Y)=[OUF(X,X) . OUF(Y,Y)] 1/2 . When the size of the field was longer than Rp, the difference between the calculated values and measured ones was relatively very small. Conclusions The output factor in rectangular fields can be accurately calculated by the equation OUF(X,Y)=[OUF(X,X) . OUF(Y,Y)] 1/2 ,which can be used in daily clinical practice. The larger the field, the more accurate the calculation.更多还原