Dosimetric evaluation of electron beams on scalp using EBT2 films and rando phantom

Abstract

BackgroundIn radiotherapy, electron beam irradiation is an effective modality for superficial tumours. Electron beams have good coverage of tumours which involve the skin, however there is an issue about electron scattering and tissue heterogeneity. This subsequently demands dosimetric analysis of electron beam behaviour, particularly in the treatment of lesions on the scalp requiring the application of treatment to scalp curvatures. There are various methods which are used to treat scalp malignancies including photons and electrons, but, the later needs precise dosimetry before each session of treatment. The purpose of the study was to undertake a detailed analysis of the dosimetry of electron beams when applied to the curved surface of the scalp using Gafchromic® EBT2 films.Methods and materialsA rando phantom and Gafchromic® EBT2 films were used for dosimetric analysis. A gafchromic calibration curve was plotted and an in-treatment beam dosimetric analysis was carried out using dosimetry films placed on the scalp. Electron behaviour was assessed by introducing five electron fields in particular curvature regions of scalp.ResultThere was an acceptable dose range through all five fields and hotspots occurred in the curved borders. In our study, skin doses and doses at the field junctions, with no gaps, were between 78–97% and 80–97%, respectively.ConclusionsElectron beams are a good modality for treating one flat field, but in the special topography of the scalp, whole scalp treatment requires precise field matching and dosimetry. In undertaking this detailed dosimetric analysis using a rando phantom and Gafchromic® EBT2 films, it is concluded that this method requires further detailed analysis before using in clinics.