The Effect of Non-carbon Fiber Base Plates on Skin Dose Increase in Radiotherapy of Breast Cancer Using Gaf-Chromic Films

Background and Due to creation of scattered radiation when using non-carbon fiber base plates particularly in treating breast cancer, applying this device can affect skin and body surface dose. Recently, using Gaf-Chromic films have led to obtaining good results in skin dosimetry. The purpose of this study was the estimation of skin dose in applying non-carbon fiber base plates using water phantom and Gaf-chromic films. In an experimental study, calibration curves in 6 and 15 MV photon mode of operation of a Siemens Primus were derived for the EB2 Gaf-Chromic films. To obtain these curves parallel plate Roos dosimeter was utilized. To measure the effect of non-carbon fiber base plate, films were attached to the bottom of a 30×30×30 cm3 water phantom and were exposed in two different energies with and without placing the non-carbon fiber base plate on the Linac coach. Calibration curves for both energies were fairly correlated to linear functions. Percentage difference for the mentioned situations (with and without using base plate) for 6 and 15 MV energies were 16.56% and 5.27%, respectively. In breast cancer radiation therapy, applying non-carbon fiber base plate, can increase the skin dose in posterior supraclavicular field. In this study the increase was more pronounced in 6 MV energy than 15 MV.