Optical response characterization of dyed-polymethyl methacrylate (PMMA) dosimeters under high-dose X-ray irradiation

This study assesses the suitability of commercial dyed polymethyl methacrylate (PMMA) dosimeters for high-dose radiation applications extending into the hundreds of kilograys. Three PMMA dosimeter types (Gammachrome YR+, Amber 3042, and Red 4034) were investigated using both online and post-irradiation optical transmission measurements in the visible spectral range. The objective was to evaluate their dose sensitivity beyond nominal operational limits and to characterize their optical response through multi-wavelength transmittance and radiation-induced attenuation (RIA) analyses. Dosimeters were exposed to X-rays at dose rates of 0.9 and 1.2 Gy[H 2 O]/s, covering doses from 0.1 Gy to 282 kGy. Monte Carlo simulations using the PHITS code were performed to model radiation transport and dose deposition in the different materials. The results demonstrate a clear, dose-dependent optical response of dyed PMMA, with wavelength-specific behavior indicative of color-center formation and evolution. Recovery measurements show that the RIA signal is highly stable over several hours at nominal wavelengths, with only minor relaxation observed in the near-infrared region, supporting the applicability of these dosimeters for both real-time and passive measurements. Comparisons with Radiophotoluminescent (RPL) FD-7 dosimeters reveal consistent trends, suggesting the potential for establishing a conversion between RPL and PMMA dose responses. Overall, the findings support the extension of dyed-PMMA dosimetry beyond current commercial limits and contribute to the development of robust dosimetry techniques for extreme radiation environments. • Dyed-polymethyl methacrylate (PMMA) dosimeters (Gammachrome YR+, Amber 3042, Red 4034) were systematically characterized under high-dose X-ray irradiation up to 280 kGy. • Monte Carlo simulations (PHITS) quantified energy deposition uniformity and established a robust conversion factor (0.73 ±0.07) between dose-to-water and dose-to-PMMA. • Online radiation-induced attenuation (RIA) and post-irradiation absorbance measurements revealed stable, dose-dependent optical responses across visible wavelengths. • RIA recovery below 3% at dosimetric wavelengths confirms dyed-PMMA’s suitability for real-time and passive high-dose dosimetry in industrial and accelerator environments.