In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting
(ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4 cm x 4.4
cm, which is pixelated into 128 x 128 square pixels with a pitch size of 350 μm 350 μm. The current detector consists
of multiple detector hybrids, each with a CdTe crystal of 1.1 cm x 2.2 cm x 1 mm, bump-bonded onto a customdesigned
application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 3264
array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry, and an analog-todigital
converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two
8-bit DACs are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a
high spatial resolution, a wide dynamic range of 12-200 keV and a good energy resolution of 3-4 keV. The hybrid
detector configuration provides a flexible detection area that can be easily tailored for different imaging applications.
The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results
We present an update on a novel direct digital X-ray imaging device and system. The system comprises a mosaic of hybrid solid state semiconductor devices removably mount onto a master plane covering an imaging surface of any desirable shape and size. Each imaging device comprises a pixel semiconductor detector flip-chip joined to a CMOS ASIC. Monolithic CdZnTe and Si pixel detectors with dimensions 12.2 X 4.2 mm2 and 18.9 X 9.6 mm2 have been implemented with a pixel pitch of 35 micrometer. Each circuit on the ASIC, corresponding to a detector pixel, is capable of accumulating thousands of X-rays in the diagnostic energy spectrum with high efficiency (CdZnTe) and user accumulation times ranging from just a few ms to a few s. Individual, removable tiles are combined in a mosaic providing continuous large area imaging with no inactive regions. This tiling approach allows for cost efficient replacement of defective tiles. The packaging delivers a compact, lightweight, portable cassette whose thickness is around 2.0 cm. The basic hybrid detector design and tiling scheme are generic and may be used in mammography, conventional radiography and fluoroscopy. A special tiling scheme has been designed for use in intraoral imaging. We present our measured Modulation Transfer Function (MTF) and Detective Quantum Efficiency (DQE). Images taken with hard objects, phantoms and soft tissue further demonstrate system functionality and provide a comparison with radiographic film and CR plates. The first application of the new technology is intended for the field of dental imaging, mammographic biopsy and other small area medical applications (approximately 10 - 30 cm2 imaging area) as well as Small Area Non Destructive Testing.