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％。 In the X-ray treatment, the radiation field output dose changes with the irradiation field changes, the change can be used to represent the field conversion factor. This factor is usually determined experimentally. In this paper, we give a empirical formula of the field conversion coefficient, which can reduce the measured workload and obtain the conversion coefficient of any field. For the clinical production of pre-set dose meter provides a convenient. Compared with the measured value, the error of the maximum point calculated by this formula is about 1%, with the error of about ± 0.3%.