|
In digital X-ray imaging, a crucial factor determining image resolution of all indirect detection systems is the spread of light in the X-ray scintillator. Currently deployed clinical x-ray detectors, with a resolution between 75 and 300 microns, are affected by such spread of light. This work demonstrates the significantly improved the resolution of an indirect X-ray scintillation detector using a new structuring approach The new structured scintillator consists of three main components: a high optical quality ‘channel plate’, a reflective material within the capillaries of the channel plate, and a polymer-based scintillating material that is incorporated in the capillaries. Channel plates, which are utilized for a variety of optical applications, are produced from bundles of hollow drawn borosilicate glass fibers, with repeated bundling and drawing reducing the diameter of the core and capillary pores down to values as low as 5 microns. These bundles are then cut to make high quality plates (‘channel plates’) with a thickness around 1 mm. Channel plates contain geometrically ordered capillary channels (about 5 million channels per square cm). The channel walls were coated with a 70 nm thick coating of Al2O3:W using atomic layer deposition (ALD) to optically confine the photoemission within the channel. The optical channel plates were infiltrated with a new bismuth-based scintillating polymer developed at Lawrence Livermore National Laboratory, with a photon yield of > 30,600 photons/keV for X-ray energies of 20-30 keV, a range of interest for mammography. The new scintillator plate was used to experimentally demonstrate an X-ray resolution of 10 microns (or 50 linepairs/ mm), an approximately 7 times improvement over existing scintillating detectors. A structured scintillator plate, coupled with a digital detection system may be used to improve the spatial resolution in applications such as mammography, radiography, and computed tomography.
|
