Résumé
Objective: Simulating the photon transport process, recording the distribution of the dose which is caused by various of interactions and secondary particles, summarizing and analyzing the weightiness of each contribution. Methods: The PENELOPE package provides the basic Monte Carlo(MC) code which simulates the processes of photon and electron transport Considering the concerned physical problems, the author modifies the PENELOPE program to simulate the track of photon transport process, meanwhile records the contribution of dose which is provided by various of interactions and secondary particles in this article. Results: Firstly, in the same condition, recording the distribution from 4 source different energies(30 keV, 40keV, 50 keV, 60 keV), the distribution of the central axis total dose and the distributions which are caused by secondary Soft collision and secondary hard inelastic collision, and the distribution of the central axis dose provided by secondary particles. Secondly, in the same condition, recording the distribution of the central axis dose caused by secondary Compton scattering and secondary Photonelectric scattering. Conclusion: In different source of energy, the distribution of the central axis dose proffered by secondary soft collision play a major role; the contribution of secondary Photonelectric scattering decreased with the ascent of energy; the contribution from the first generation secondary particles is stronger than others.