Radiochromic polymer film dosimeters are strong candidates for radiation therapy dosimetry due to high spatial resolution, tissue-equivalency, relative ease of use, and the ability to provide two-dimensional measurement. In this work, we studied the growth kinetics of optical density of EBT3 and EBT-XD radiochromic film models, irradiated using megavoltage photon and proton therapy beams, over a period of 5 min to 120 hours post-irradiation.
Radiochromic films, owing to their high spatial resolution, are well-suited for radiation therapy dosimetry and quality assurance purposes. However, their spectroscopic response to radiotherapy beams has not been comprehensively investigated, except for a limited subset of beam qualities. In this work, we explore the spectral response of the EBT3 and EBT-XD radiochromic film models to different clinical radiation beam qualities including photons and protons. The spectral response of EBT3 and EBT-XD films showed two peaks at 585 nm and 635 nm for both photon and proton irradiation. Beyond a certain batch- and model-dependent dose threshold a saturation behavior was observed in the primary absorption peak. For beam qualities studied in this work, the spectral response of proton-irradiated films showed a systematic under-response compared to their photon-irradiated counterparts in both EBT-3 and EBTXD radiochromic films models.
Radiochromic films are commonly used in radiation therapy dosimetry and quality assurance. However, their spectral response is studied only for a limited set of beam qualities used in radiation therapy. In this work, we investigate the spectral response of the EBT3 radiochromic films for a broad range of megavoltage photon and electron radiation beam qualities. Dose, dose rate, and inter-batch dependencies are investigated. For beam qualities studied in this work, we found that for a given batch, the spectral response of the EBT-3 radiochromic films is beam quality and dose-rate independent. However, the spectral response of the films is batch-dependent.