On the spectral characterization of radiochromic films irradiated with clinical proton beams.

On the spectral characterization of radiochromic films irradiated with clinical proton beams. Phys Med Biol. 2019 Jul 05;64(13):135016 Authors: Darafsheh A, León-Marroquín EY, Mulrow DJ, Baradaran-Ghahfarokhi M, Zhao T, Khan R Abstract Radiochromic films have been widely studied for clinical dosimetry in conventional external beam radiation therapy. With an increase in practice of proton therapy, such films are being conveniently used; however, their spectroscopic characterization for this modality is lacking. This work investigated the response of the EBT3 radiochromic films irradiated in a Mevion S250™ clinical proton beam. Dose, dose rate, inter-batch, sensitivity, and linear energy transfer (LET) dependencies of the films were studied. Pieces of the radiochromic films from different batches were irradiated using a spread-out Bragg peak (SOBP) proton beam at dose levels between 0.1-15 Gy. Absorption spectra were measured in the wavelength range of 400-800 nm with 2.5 nm resolution. For comparison, the optical density of the films was measured using a flatbed scanner. The net absorbance spectra showed two characteristic absorption bands centered at 636 nm and 585 nm. However, a saturation effect, manifested as broadening/splitting appearance, was observed in the 636 nm band for doses beyond a certain batch-dependent level ~4-10 Gy, in the three different film batches studied. The differences in the spectral shape led ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research