A Study on the dosimetry in boundary of shielding block in high energy irradiation

Kim, Myung Se; Kim, Sung Kyu; Shin, Sei One

Abstract

Scatter-air ratios are used for the purpose of calculating scattered dose in the medium. The computation of the primary and the scattered dose separately is particularly useful in the dosimetry of irregular fields with shielding block in radiation field, dose distribution of scattered radiation using 18MeV Linear accelerator and Co-60 teletherapy measured. The effect of scattered radiation dose by protecting block was been ignored in radiation therapy, 2-3% of scattered radiation may be 90-200cGy which could be influence vital complication such as cataract, oligospermia or sterility. So that exact calculate scattered radiation by protecting block exactly for irregular field c small protection of vital organ is very important. The purpose of this article is to calculate scattered radiation by protecting block exactly for irregular field c Linac or Co-60 irradiation and to applicate these data in clinical radiation field. Authors could obtain following results. 1. The lesser angle between shielding block showed more scattered radiation. 2. With decreasing distance between shielding blocks, the dependent of scattered radiation were increased. 3. Output of 18 MeV Linear accelerator and Co-60 was related linear proportion on field size, but independent according to the size of shielding block in 18 MeV Linear accelerator.