An approach to 3D dose mapping using Gafchromic film

The tissue equivalent composition of the Gafchromic films makes them particularly suitable for the mapping of 2D and 3D treatment fields. This paper presents the results obtained using MD-55 film for the verification of real radiotherapy treatments through proton beam irradiation of suitable phantoms at the Clatterbridge Centre for Oncology (CCO) in Bebington (UK). After exposure, the variation in optical density of the films was measured using a CCD100 Microdensitometer (source at 665 nm). Holes of calibrated diameter, made during the assembly phase of the phantom, are identified by the MIRA software, used for data analysis, and allow the rendering of the films. The surface dose distributions were obtained from the variation in optical density of each of the films making up the phantom. Their elaboration to duplicate their position within the phantom, performed by 3D-doctor software, allows the volumetric reconstruction of the dose distribution.