RESUMO
PURPOSE: The purpose of this study was to understand the PDD and OAR during electron beam therapy using lead cutout on the body surface. METHODS: The Monte Carlo code PHITS version 3.24 was used to simulate PDD and OAR. The simulation results were compared with actual measurements using a silicon diode detector to evaluate the validity of the simulation results. RESULTS: The simulated PDD and OAR parameters of the linac agreed with the measured values within 2 mm. When the lead cutout on the body surface was used, all parameters except for R100 agreed with the measured values within 2 mm. The cutout sizes of the broad-beam square irradiation fields were 3 cm for 6 MeV, 5 cm for 12 MeV, and 8 cm for 18 MeV when the lead cutout on the body surface was used. CONCLUSION: The Monte Carlo simulation was useful for understanding the PDD and OAR of the lead cutout irradiation fields, which are difficult to measure.
