Optics-based X-ray Imaging systems and High Resolution Imaging Plates
There has been a revolution in X-ray imaging in the last twenty years, with traditional photographic film/phosphor methods being replaced by digital techniques, including storage phosphor, CCD/phosphor, CMOS/phosphor and photoconductor array methods.
Storage phosphors based on the photo-stimulated luminescence effect offer many advantages over film, but suffer from inferior spatial resolution. The problem lies in the light scattering from the powder grains of the storage phosphor (usually BaFBr:Eu). This problem rules out storage phosphors for mass radiography applications such as mammography.
Our research into nano-structured materials such as glass ceramics and polymer-nanocrystal composites seeks to combine good storage phosphor properties with high transparency.
Our objective for dual-energy plates is to make screens which can record not only the shadow image of an object for polyenergetic X-rays, but also the division of the image into separate energy bands. In practice, the image will be recorded for just two different X-ray energies, but this will yield invaluable information on the chemical content of the object being imaged, since elements with small atomic numbers are much more transparent to X-rays than those with high atomic numbers.
We are also working on stratified imaging screens which can distinguish neutron from gamma and x-ray radiation, and single mode plates for high resolution. The materials we work with include transparent glass ceramics and crystal-resin composites.
We are researching radiation dosimeter materials and devices. Our particular emphasis is on materials that have a response to radiation that is similar to tissue where the applications include quality assurance for medical linear accelerators and other radiation sources. We are studying bulk and nanoparticle fluoroperovskites where the materials exhibit radioluminescence during exposure to ionizing radiation and optically stimulated luminescence after exposure to ionizing radiation.