A novel 3D polymer gel dosimeter based on polymethyl methacrylate gel (PMMAG) for radiotherapy: Ultrasonic evaluation

This study investigates the characteristics of a novel polymer gel dosimeter (PMMAG) for radiotherapy applications, focusing on its radiation absorption and sensitivity properties. The PMMAG dosimeters were evaluated using both UV–vis spectrophotometry and ultrasonic techniques. The results of the study, UV–vis analysis revealed a significant increase in dose response with the introduction of a cross-linker, peaking at a monomer-to-cross-linker ratio of 5:3. Sensitivity analysis indicated optimal sensitivity at this ratio, with values reaching 0.021 a.u./Gy. Ultrasound evaluation showed that the speed of sound and attenuation coefficient demonstrated a linear relationship and a strong positive correlation with an increase in the applied radiation dose, with the highest sensitivity observed at 8 Gy. The optimal sample exhibited the highest dose-response values at both 4 Gy and 8 Gy doses. Sensitivity values ranged from 2.1 to 2.75. The ultrasonic measurements demonstrated a significantly larger dynamic range in dose response curves compared to UV–vis dose-response data. It is concluded that ultrasound shows great potential as a technique for the evaluation of polymer gel dosimeters. The PMMAG can be introduced as a novel dosimeter for ionizing radiation dosimetry, validated through both optical and ultrasound assessment methods. The consistent and reliable performance of the PMMAG dosimeters makes them suitable for various applications in radiation therapy.