Feasibility of an overhead scanning system for radiochromic film dosimetry of therapeutic X-rays

Abstract Gafchromic films, commercially available self-developing radiochromic films, are useful for two-dimensional radiation dosimetry. However, the effects of film orientation and lateral response artifact (LRA) can lower the accuracy of determined doses. In this study, we investigate the feasibility of a new film-scanning method with an overhead scanner (OHS), compared to those with a conventional flatbed scanner (FBS). Gafchromic EBT3, EBT4, and EBT-XD films irradiated with LINAC 6 MV X-rays used for radiotherapy were scanned in portrait (standard) and landscape (perpendicular) orientations using OHS (CZUR Aura) and FBS (EPSON GT-X980), and the optical density (OD) profiles of the RGB color channels were analyzed. All film types, particularly EBT-XD, showed more linear dose responses and less orientation effects in OHS scanning than in FBS scanning, whereas dose profiles obtained with OHS and FBS showed comparable LRA effects in both orientations. These findings indicate the potential of the OHS scanning system for establishing a more reliable dosimetry using Gafchromic films. Further investigation to reduce the LRA effects is required for the implementation of this OHS scanning system for radiotherapy.