X ray storage performance of KCl:Eu with high cumulated dose.

The effects of high cumulative radiation dose on the luminescence properties of KCl:Eu are investigated. Pellet samples of KCl:Eu were given doses of up to 200 kGy at the Louisiana State University Synchrotron facility. After synchrotron irradiation, samples were optically bleached and given a clinical dose of 2 Gy from a 6 MV medical linear accelerator. Optical properties were evaluated using photostimulated luminescence (PSL), photoluminescence (PL), and temperature-dependent PSL measurements. For a cumulated dose of up to 5-10 kGy, the PSL emission intensity increased by 15% compared to the PSL signal with no radiation history. For doses higher than 10 kGy, the PSL emission intensity retained at least 70% of the original intensity. Spatial correlation of the charge storage centers increased for doses up to 5 kGy and then decreased for higher cumulative doses. Emission band at 975 nm was attributed to transitions of Eu. PL spectra showed an intense peak centered at 420 nm for all cumulative doses. The results of this work show that KCl:Eu storage phosphors are excellent reusable materials for radiation therapy dosimetry.