Fluorochlorozirconate Glass Ceramics for Computed Radiography

Heat treating fluorochlorozirconate (FCZ) glasses nucleates nanocrystals in the glass matrix, resulting in a glass ceramic that has optical properties suitable for use as a medical imaging plate. As the temperature of heat treatment rises, the resulting FCZ glass-ceramic becomes increasingly more opaque as the size of the orthorhombic phase BaCl­₂[barium chloride] nanocrystals grow within the glass matrix. This opaqueness negatively affects imaging. The effect of adding Fe³⁺[iron] on the valence state of zirconium and overall glass quality was investigated.

Samples were synthesized and characterized with differential scanning calorimetry to determine the temperature of the orthorhombic BaCl₂[barium chloride] phase transition. Samples were then heat treated to create a glass ceramic with the desired storage phosphor properties. Phosphorimetry and x-ray diffraction (XRD) experiments were performed on the glass ceramics to confirm crystal phases. Finally, photostimulated luminescence (PSL) experiments were performed to measure light output. Results showed that the addition of small amounts of FeCl₃[iron chloride] (1-2%) to a ZBLAN glass composition allows for the precipitation of orthorhombic phase BaCl₂[barium chloride] crystals while maintaining transparency of the glass-ceramic.

Additionally, larger FCZ plates were synthesized and heat treated for performance testing as a storage phosphor image plate. Plates were exposed at various x-ray energies (45 keV - 1 MeV) and used to image numerous phantoms and everyday items. The suitability of fluorochlorozirconate glass as a storage phosphor imaging plate for computed radiography was evaluated.