A 48/spl times/48 CdZnTe array with multiplexer readout

Abstract

We report results of gamma-ray imaging and energyresolution tests of a 48x48 CdZnTe array. Our detectors have 125 pm square pixel electrodes produced by photolithography and are indium-bump-bonded to a multiplexer readout circuit. Using a collimated beam of 140 keV gamma rays of 120 pm diameter centered on one pixel, we found that the majority of events produced significant charge deposition in nearby pixels. Charge and energy are transported out of the pixel by charge diffusion, photoelectron range, Compton scattering, and escape of K x rays. These effects also distort single-pixel spectra, although photopeaks are still discernible at 140 keV. When signals from neighboring pixels are summed together to correct for this charge spreading, an energy resolution of 10 keV is obtained at 140 keV. Corrections will be simpler and energy resolution should be better for the 380 pm pixels of the 64x64 CdZnTe arrays we are constructing for an ultrahigh-resolution brain imager. 0018-9499/96$05.00 0 1996 IEEE

Imaging performance comparison between a scintillator based and a CdTe semiconductor based photon counting compact gamma camera

“…The University of Arizona group developed CdZnTe detectors for gamma-ray imaging with submillimeter pitch, with most work dedicated to the development of 380 m pitch 64ϫ 64 detector arrays. [35][36][37][38][39] Prototype SPECT systems for small animal imaging using one such detector head have been reported. [36][37][38][39] The evolution of these prototypes leads to the recent realization of the very complex and high performance SemiSPECT small animal SPECT imager, 41 which employs eight compact detector heads based on CdZnTe detectors ͑64ϫ 64 pixels each, 380 m pitch, 2 mm thick-ness͒.…”

“…In the case of CdTe or CdZnTe, other groups have experimented hybrid detectors for nuclear medicine imaging with 1-6 mm thick detectors and with array sizes up to 64ϫ 64 and a pixel pitch in the range 1-4 mm ͑Refs. 27-31 and 66͒ or a fraction of a millimeter ͓e.g., 125 m, 35 27 Since a photon counting ͑hybrid͒ detector stores in each pixel only the total number of detected photons during the exposure, the information on the energy deposited by each photon in the detector volume is limited to the energy window selected. This is analogous to scintillator based detectors, where the energy windowing process allows to reject those photons depositing energy outside a range around the main photopeak for the specific gamma-ray source.…”

SPECT detectors: the Anger Camera and beyond

“…The clocked gated-integrator approach (Marks et al 1996) shares similarities with CCD and CMOS readout in that a fixed acquisition period is followed by readout of the accumulated signals on all channels. One benefit of gated integrators is that the control logic and readout is straightforward.…”

A new digital-analog multiplex method using an adder circuit

“…1 Introduction/motivation Two-or three-dimensional position-sensitive radiation detectors play an important role in the field of nuclear medicine, astrophysics, and homeland security [1]. Because recent two-or threedimensional detectors have hundreds of channels, a signal multiplex is needed to reduce read-out channels [2]. One well-known pulse-processing method in the field of radiation detection is the Time-over-Threshold (ToT) method [3], which converts the analogue pulse height into a digital pulse width using a comparator.…”