Direct-conversion x-ray imaging detectors for medical nondestructive testing (NDT) and other applications

Direct conversion of x-ray energy into electrical charge has been extensively developed into imaging products in the past few years. Applications include general radiography, mammography, x-ray crystallography, portal imaging, and non-destructive testing. Direct methods avoid intermediate conversion of x-rays into light prior to generating a measurable electrical charge. This eliminates light scattering effects on image sharpness, allowing detectors to be designed to the limit of the theoretical modulation transfer function for a discrete-pixel sensor. Working exposure range can be customized by adjusting bias and thickness of sensor layers in coordination with readout-electronics specifications. Mature amorphous selenium technology and recent progress on high-quality Thin-Film Transistor (TFT) arrays for computer displays have allowed development of practical large-area high-resolution flat-panel x-ray imaging systems. A variety of design optimizations enable direct-conversion technology to satisfy a wide range of applications.

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