RESUMO
PURPOSE: We compared the calculated percent depth dose curves of 6 MeV electron beam to that of measured to evaluate the usefulness of Monte-Carlo simulation method in radiation physics. MATERIALS AND METHODS: The radiation dose values of 6 MeV electron beam using EGS4 code with one million histories in water were compared values that were measured form the depth dose curve of electron beam irradiated by medical accelerator ML6M. The central exis dose values were calculated according the changing field size, such as 5 X 5, 10 X 10, 15 X 15, 20 X 20 cm2. RESULTS: The value calculated showed a very similar shape to depth dose curve. The calculated and measured value of Dmax at 10 X 10cm2 cone is 15mm and 14mm respectively. The calculated value of the surface radiation dose rate is 65.52% and measured one is 76.94%. The surface radiation dose rate has vaied from 64.43% to 66.99. The calculated values of Dmax are in the range between 15mm and 18mm. The calculated value was fitted well with measured value around the Dmax area, excluding build up range and below the 90% depth dose area. CONCLUSION: This result suggested that the calculation of dose value can be replace the direct measurement of the dose for radiation therapy. Also, EGS4 may be a very convenient program to assess the effect of radiation dose using by personal computers.