Impact of Monte Carlo simulation for radiotherapy

This paper explained the application of Monte Carlo simulation in the radiotherapy field, and verified its utility. Firstly, it explained the basis of Monte Carlo method, took up the beam modeling of the photon beam and electron beam of medical linear accelerators using EGS4/BEAM code, and verified the precision of modeling through comparison between the dose distributions inside a water phantom obtained from the measurement and calculation. It also calculated energy spectrum and water/air collision stopping power ratio at the incidence plane of the phantom. Secondly, in order to verify the dose calculation precision in the heterogeneous region of the calculation algorithm of radiotherapy program, it compared the results of EGSnrc Monte Carlo code and the dosimetry by means of ionization chamber, using a lung phantom as a model. It further compared the dose distribution and dose volume histogram (DVH) of the calculation algorithm in stereotactic lung radiotherapy. Finally, in order to evaluate the exposure dose of kV-CBCT in image-induced radiotherapy, it conducted beam modeling using EGSnrc/BEAMnrc code and DOSXYZnrc code. Thus, it obtained DVH from energy spectrum at phantom incidence plane and dose distribution calculation at the pelvis part, and calculated the organ dose. (A.O.)