Estimation of Contralateral Breast Dose for Tangential Breast Irradiation Using Gafchromic Film Ebt2

Abstract

The dose to the contralateral breast for tangential breast irradiation has been estimated using Gafchromic films EBT2. The data collected consisted of measurements taken with anthropomorphic female Rando phantom. The EBT2 films were scanned and read using ScanMaker 9800XL plus and ImageJ software. A calibration curve was constructed using fourth – order polynomial fit to the data and a calibration equation was obtained from the graph which was used to convert the grey values into doses. Comparison of dose to the contralateral breast using different wedge angles and different photon beam energies has been done. The mean dose to the contralateral breast recorded were 1.93 Gy and 3.14 Gy for 6 MV and 15 MV photon beams respectively. The results show that the mean dose to the contralateral breast for 6 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30Oand 15O wedges respectively. Similarly the mean dose to the contralateral breast for 15 MV using 60O motorised wedge produced higher surface dose to the contralateral breast than 30O and 15O wedges respectively. Results from this study show that the dose to the contralateral breast increases with increasing wedge angle. Analysis of the results from the 6 MV and 15 MV shows that the 15MV photon beam produced a higher doses to the contralateral breast as compared with the 6 MV photon beam by 6.42%.