能量吸收系数μ_a常随体模的深度而变化,主要是由于平均能量随深度变化所致,而平均能量又依赖于能谱的分布。我们研究了从~(60)Co到10Mv-X线零照射野的积分能量吸收系数随深度的依赖关系(表1)。得出 The energy absorption coefficient μ_a often varies with the depth of the phantom, mainly due to the variation of the average energy with the depth, and the average energy depends on the distribution of the energy spectrum. We studied the dependence of the integral energy absorption coefficient with depth on the zero-radiation field from ~ (60) Co to 10Mv-X (Table 1). inferred