This study examined the response characteristics of three commercially available radiochromic films when exposed to very low energy (50 kVp) X-rays. The aim was to evaluate the films for potential use in 2D dosimetry for a low-kV intraoperative radiotherapy (IORT) device. Dose-response relationships were obtained for Gafchromic® EBT, XR-RV2 and XR-QA film in water at several distances from the IORT source in order to evaluate the effect of changes in X-ray spectrum on response. It was found that the dose-rates from the source were excessive for use of the XR-QA film, and that all three film types films showed significant energy dependence within the limits of measurement uncertainty. This is in contrast to previous studies indicating less or negligible energy response. All films showed non-linearity in response over the ranges examined. These results imply significant limitations for the use of these films for low-kV dosimetry.
Ebert, M., Asad, A. H., & Siddiqui, S. A. (2009). Suitability of radiochromic films for dosimetry of low energy X-rays. Journal of Applied Clinical Medical Physics, 10(4), N/A. https://doi.org/10.1120/jacmp.v10i4.2957