Mercury iodide flat panel radiation detector for simultaneous acquisition of static and moving image

Mercuric iodide deposited on flat panel thin film transistor (TFT) array is one of the best alternate photoconductive materials for direct digital X-ray detectors for both static and moving image application in medical imaging. The mercuric iodide is coated onto the array by a Particle-In-Binder (PIB) process and scaled up to the 7inch 8.5inch size required in common medical imaging application. A TFT array with a pixel pitch of 139microns was used for detector. Mercuric iodide coating thickness around 200 microns was tested with beam energy between 40kVp and 100kVp utilizing exposure ranges typical for both static and dynamic imaging. Detector performances were evaluated by obtained images. Mercuric iodide deposited on flat panel thin film transistor (TFT) array is shown to exhibit high sensitivity to X-rays, excellent spatial resolution and high Detective Quantum Efficiency (DQE). Especially it is quite suitable for moving image because of low image lag. Resolution tests on resolution target phantoms showed that resolution is limited to the Nyquist frequency for the 139 microns (resolution ~3.6lp/mm) pixel detectors. The ability to operate at low voltages (~100V) gives adequate dark currents for most application and allows low voltage electronics designs. Also the detector can use exceptionally low dose-rate X-ray illumination because of the very high X-ray sensitivity, which exceeds any other known X-ray detector material. The fabricated detector represents the most advanced photoconductor material available today for flat panel, high resolution, x-ray, medical detector, which alternates conventional a-Se technology.