Iwasaki A
Med Phys. 1985 Nov-Dec;12(6):731-7. doi: 10.1118/1.595656.
The complete distribution of high-energy photon primary absorbed dose along the beam path within a semi-infinite or finite water phantom can be expressed by one functional equation. The derivation is based on a technique of convoluting a primary collision kerma distribution function with a pair of forward and backward spread dose-distribution functions. In particular, the characteristic patterns of primary dose in the regions near the beam entrance and exit surfaces can be obtained. The calculated ratio of primary dose to primary collision kerma in the electron-equilibrium region in water for 60Co radiation is 1.0060 and that for 25-MV radiation is 1.0444.
高能光子原发射线吸收剂量在半无限或有限水模体中沿射线路径的完整分布可用一个函数方程表示。该推导基于一种将原碰撞比释动能分布函数与一对前向和后向展宽剂量分布函数进行卷积的技术。特别地，可以得到射束入射面和出射面附近区域的原发射线剂量的特征模式。计算得出，水中电子平衡区域内60Co辐射的原发射线剂量与原碰撞比释动能之比为1.0060，25兆伏辐射的该比值为1.0444。
