UV radiation dosimetry using EBT3 detector optimized by ion beam-modified PET barrier

Monitoring ultraviolet radiation (UVR) levels over time is crucial, as it can impact human health. This study examines the use of modified polyethylene terephthalate (PET) film as a barrier to control the performance of external beam therapy (EBT3) detectors in long-term UVR dosimetry. The investigation begins with a thorough characterization of the modified films surface. Atomic force microscopy (AFM) showed an increased surface roughness from 2.3 nm for the pristine PET film up to 17.6 nm for the sample irradiated by the highest ion fluence. The crystallite size reduction is also confirmed by X-ray diffraction (XRD) analysis due to the destruction and disordering of the original lamellar structure. Fourier Transform Infrared (FTIR) spectroscopy revealed increased oxygen-containing groups (C--O, O-C--O, and C-O), enhancing wettability. Also, the surface free energy components are found to increase after irradiation by 200% larger than the pristine PET film. UV-vis spectroscopy showed that the ion beam-modified PET maintained high visible light transparency, 86% and 77%, for the lowest and highest ion fluence, respectively. While modified PET film showed controlled UVR barrier properties, 99% of UVC, 92% of UVB, and 69% of UVA were blocked for the highest applied fluence. Finally, the modified PET films are tested as protective barriers for EBT3 detectors. EBT3 detectors shielded by pristine PET barriers have a limited UVR detection range of 4-50 J/cm2. However, modifying the PET barrier with a higher ion beam fluence extends the UVR detection range to 520 J/cm2. This allows EBT3 detectors to operate for an extended period, surpassing their counterparts with no barriers, which can only detect up to 25 J/cm2. The current research emphasizes the ion beam's capability to tailor the surface characteristics of PET film, making it a valuable tool for optimizing the optical response of EBT3 detectors for long-term UVR dosimetry.