Feasibility study on CaF₂:N films for 2D real-time dose mapping under ultra-high dose rate electron beams in FLASH radiotherapy

Le résumé fourni par la source

Ultra-high dose rate radiotherapy (UHDR-RT) is an emerging cancer treatment technique that triggers the FLASH effect which minimizes healthy tissue damage while controlling tumors. However, clinical implementation of UHDR-RT is hindered by the lack of dedicated machines and standardized dosimetric procedures. Accurate UHDR-RT dosimetry requires advanced detectors that address challenges such as saturation and dose rate dependence. Radioluminescence has emerged as a promising technique for UHDR dosimetry, offering high spatial and temporal resolution for real time multidimensional measurements. This study evaluates 2D RL films based on natural Brazilian calcium fluoride (CaF₂:N) for UHDR electron beam dosimetry. Films with different grain sizes and CaF₂ concentrations were irradiated using an ElectronFlash linac, assessing pulse length dependence, field size, and dose linearity. The CaF₂:N films were explored for dosimetry application in conventional mode for comparison. Results demonstrated linear RL dose-response in both conventional and UHDR modes, with higher RL intensity for films containing 54% CaF₂ and larger grains. Field size analysis matched Gafchromic films, though signal attenuation occurred due to phantom surface artifacts. Despite energy dependence, CaF₂:N films exhibited spatial homogeneity and flexibility, and desirable dosimetric features, making them suitable for 2D dose mapping. With optimized acquisition systems and reduced luminescent lifetime, CaF₂:N films could advance UHDR-RT dosimetry by combining real time, high-resolution, and cost-effective dose monitoring.

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