辐射治疗能区内电子束在轻介质中的平均能量计算

THE CALCULATION OF MEAN ENERGY FOR ELECTRON BEAM IN THE ENERGY RANGE OF RADIO THERAPY IN LIGHT MEDIA

In this paper a, Gaussian distributioll,for electron energy, is. deduced by Fokker-Planck approximation to the Boltzmann equation for high-energy electrons penptrating in multi-constituents media, then a recursin-iteration, algorithm for the mean energy leaiculation of hish-energy.electron beam is obtained after introducing the modified CSDA mean energy and uking Yang'a mtltipole scattering. theory.Some calculational results of. this algorithm are also given in the article and compared with corresponding data of Monte Carlo siamultions, and experimental mea measurements. The comparison shows that the algorithm can precisely predict the coenergy of high-energy electron beam penetrating in light media. Furthermore, two common forinulae for electron beam mean energy calculation in radiotherapy dosealgorithms. i. e., the Harder formula and Brahme.formula, are discussed ;and a more accurate semi-empirinal formula is recommended in this paper as well.