2D and 3D dose distribution determination in proton beam radiotherapy with GafChromic film detectors

This paper presents the results obtained using radiochromic (MD-55 GafChromic) film for the 2D and 3D dosimetric reconstruction of the dose delivered by a proton beam under the real conditions of a programme of radiotherapy treatment for ocular tumours. Standard microdensitometric measurements were used to determine the variation in film optical density (O.D.) vs dose. Calibration curves were obtained by least-square fitting of the experimental OD values using a second order polynomial. This allows conversion of O.D. to dose. With this procedure it was possible to determine the distribution of the dose delivered by the proton beam in a phantom composed of layers of GafChromic film, with high surface spatial resolution and, through sections, the complete mapping of the dose delivered to a volume subjected to irradiation, as in a course of radiotherapy treatment.