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

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 (SiO 2 –Al 2 O 3 –CaF 2 –CaO–SmF 3 ) plates, which contain trivalent‐samarium‐doped calcium fluoride (CaF 2 :Sm 3+ ) nanocrystals, for use as a dosimetric detector material, particularly for MRT applications. Our approach utilizes the extent of Sm 3+ →Sm 2+ 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 Sm 3+ →Sm 2+ valence reduction takes place in CaF 2 nanocrystals, but not in the glass matrix. The Sm 2+ shows PL emission predominantly due to the fast 4 f 5 5 d 1 → 7 F 0 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 Sm 2+ 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 CaF 2 nanocrystals reported in this work shows potential for practical use in high‐dose and high‐resolution dosimetry for MRT .