Samarium‐Doped Oxyfluoride Glass‐Ceramic as a New Fast Erasable Dosimetric Detector Material for Microbeam Radiation Cancer Therapy Applications at the Canadian Synchrotron

Abstract

There is a special need to develop a dosimetry technique with a large‐dynamic range and high‐spatial resolution to characterize the microstructured X‐ray beams used in microbeam radiation therapy (MRT) for cancer. We report the synthesis and characterization of oxyfluoride glass‐ceramic (SiO2–Al2O3–CaF2–CaO–SmF3) plates, which contain trivalent‐samarium‐doped calcium fluoride (CaF2:Sm3+) nanocrystals, for use as a dosimetric detector material, particularly for MRT applications. Our approach utilizes the extent of Sm3+→Sm2+ valence reduction caused by X‐ray irradiation as a probe of the X‐ray dose delivered; and confocal fluorescent microscopy is used to read out the distribution of valence reduction through the photoluminescence (PL) signal. Our study showed that the Sm3+→Sm2+ valence reduction takes place in CaF2 nanocrystals, but not in the glass matrix. The Sm2+ shows PL emission predominantly due to the fast 4f55d1→7F0 transition, which allows us to read out the detector plate at a high scanning speed. Further, our experiments showed that the detection dose range reaches several thousands of grays, and X‐ray dose distribution is detected at a micrometer scale. In addition, the Sm2+ signal can be erased either by heating the irradiated sample at a suitable high temperature or by exposing it to UV light; and the erased glass‐ceramic plate is reusable. The new Sm‐doped oxyfluoride glass‐ceramic with CaF2 nanocrystals reported in this work shows potential for practical use in high‐dose and high‐resolution dosimetry for MRT.