Mills M D, Hogstrom K R, Fields R S
Med Phys. 1985 Jul-Aug;12(4):473-6. doi: 10.1118/1.595674.
The demands of a busy clinic require that basic machine calculations be performed as accurately, rapidly, and simply as possible. For the electron beam of the Therac 20 Saturne linear accelerator, a method suitable for a programmable calculator is described to predict the dose output from the measurement of selected fields. One-dimensional output factors were measured; these are defined as output factors of rectangular fields where one side is always equal to the side of the square reference field. The output of an arbitrary rectangular field X, Y is given by the product of the output factors OF(X,Y) = OF(X,10) X OF(10,Y), where 10 is the side of the square reference field. The measured data indicate that the output of very large rectangular and square fields is underestimated using this method for the lower energies. A correction factor of the form CF = C X [(X - 10)(Y - 10)/(X - 10)(Y - 10) 1/2] results in agreement with measured data to within 1.5% for all energies.
繁忙诊所的需求要求尽可能准确、快速且简单地进行基本的机器计算。对于Therac 20 Saturne直线加速器的电子束，描述了一种适用于可编程计算器的方法，用于根据选定射野的测量值预测剂量输出。测量了一维输出因子；这些被定义为矩形射野的输出因子，其中一边始终等于方形参考射野的边长。任意矩形射野X、Y的输出由输出因子的乘积给出，即OF(X,Y) = OF(X,10) × OF(10,Y)，其中10是方形参考射野的边长。测量数据表明，对于较低能量，使用此方法会低估非常大的矩形和方形射野的输出。形式为CF = C × [(X - 10)(Y - 10)/(X - 10)(Y - 10) 1/2]的校正因子使得在所有能量下与测量数据的一致性在1.5%以内。
