X线照射野转换系数经验公式

AN EMPIRICAL FORMULA OF RADIATION FIELD OUTPUT FACTOR FOR X-RAYS

在X线治疗中,射野输出剂量是随着照射野变化而变化的,其变化可用野转换系数表示。通常该系数是用实验来测定的。本文给出了一个野转换系数经验公式,这样既可减轻实测工作量,又可获得任意野的转换系数。为临床制作开机预置剂量表提供了方便。本公式计算的野转换系数与实测值相比,最大点的误差约为1％,或然误差约为±0.3％。

It is well known that the output factor of absorbed dose of radiation field varies with the size under the same exposure of X-ray. The output factor is usually measured directly in a water phantom. An empirical formula of FOF is provided in the paper, so as to make it easy to calculate the FOF by the formula. This formula has been used in our department, and has shown that it can fit either to accelerator,cobalt, or even deep X-ray machine.Comparing the calculated and the measured data in a wider range, the maximal error is 1% and the probability error is ±0.3%.