Author: Kuan Ling Chen, Jiajin Fan, Rao Khan, Robabeh Rahimi 👨🔬
Affiliation: University of Maryland, Inova Schar Cancer Institute, Howard University 🌍
Purpose: This study evaluates the dose response, energy dependency, sensitivity, reproducibility, temporal response, and LET dependency along and in the plane perpendicular to a clinical proton beam for radiochromic film models EBT3 and EBT4.
Methods: Pieces of radiochromic film models EBT3 and EBT4 were irradiated in a clinical proton beam of various energies and doses. Multiple batches of new EBT4 films were used to assess inter-batch and intra batch variations. Films reproducibility was also studied by irradiation on different days. The irradiated films were scanned using a flatbed scanner and analyzed with ImageJ software. Calibration curves were developed, and the films were assessed for their dose response, sensitivity, reproducibility, energy dependency, LET dependency in the beam path and in the plane perpendicular. For temporal evolution, films were scanned from 0-120 hours after irradiation at various intervals.
Results: The EBT4 films demonstrated reliable dose-response characteristics, reproducibility, and acceptable inter-batch consistency. Sensitivity and temporal evolution were also verified. EBT4 films require LET correction for accurate dosimetry at the Bragg peak and penumbra region. Comparably, these characteristics were found to be similar to those of EBT3 films.
Conclusion: EBT4 films satisfy the required accuracy and reliability and have the potential to be integrated into clinical proton beam therapy dosimetry.