Determining The Accuracy of Dwell Position by Using Electron Energy with Gafchromic Film in High Dose Rate Brachytherapy Systems

Abstract

Due to the general lack of darkroom and film processing equipment in many clinics, it is no longer possible to use radiation sensitive Xomat V radiographic film for High Dose Rate brachytherapy quality assurance. An alternative is to use radio chromic film that does not require processing. The aim of this study is to develop and clinically test the GafChromic film-based brachytherapy Quality Assurance (QA) system using different electron energies. As an electron source (6 MeV-9 MeV-12 MeV -15 MeV -18 MeV) (Elekta Synergy® Platform linear accelerator, Varian GM plus IX (Varian Medical Systems, Inc.USA), Varian brand cylinder, ring and tandem double ovoid applicators, RTQA2 and EBT3 GafChromic film were used. In RTQA2 films, images are obtained at high electron energies (12 MeV and above) at 300 Monitor Unit (MU), while images are obtained at all energies at 700 MU in irradiation using different electron energies and MUs. For the desired image quality depending on the material of the applicator used, it was determined that the image clarity increased as the energy, field size and MUs increased. In EBT3, the desired image could be obtained at 18 MeV and 2500 MU. It is possible to obtain the desired image quality by using high-energy electrons, especially RTQA2 Gafchromic film, in determining the accuracy of the dwell position in brachytherapy. Since it has been determined that this method can be used easily in quality control tests, we think that this method is suitable for clinical use when necessary.