Development of a simplified simulation model for performance characterization of a pixellated CdZnTe multimodality imaging system

Abstract

Current requirements of molecular imaging lead to the complete integration of complementary modalities in a single hybrid imaging system to correlate function and structure. Among the various existing detector technologies, which can be implemented to integrate nuclear modalities (PET and/or single-photon emission computed tomography with x-rays (CT) and most probably with MR, pixellated wide bandgap room temperature semiconductor detectors, such as CdZnTe and/or CdTe, are promising candidates. This paper deals with the development of a simplified simulation model for pixellated semiconductor radiation detectors, as a first step towards the performance characterization of a multimodality imaging system based on CdZnTe. In particular, this work presents a simple computational model, based on a 1D approximate solution of the Schockley-Ramo theorem, and its integration into the Geant4 application for tomographic emission (GATE) platform in order to perform accurately and, therefore, improve the simulations of pixellated detectors in different configurations with a simultaneous cathode and anode pixel readout. The model presented here is successfully validated against an existing detailed finite element simulator, the multi-geometry simulation code, with respect to the charge induced at the anode, taking into consideration interpixel charge sharing and crosstalk, and to the detector charge induction efficiency. As a final point, the model provides estimated energy spectra and time resolution for (57)Co and (18)F sources obtained with the GATE code after the incorporation of the proposed model.

A study of pixilated CdZnTe detectors for neutrino research

“…As explained in Ref. [12], the weighing potential under the pixel can spread outside the material located under the pixel and induced current can flow in the opposite direction to produce negative waveforms [13]. The bipolar pulses observed in this particular event may contain contributions from different charge induction mechanisms among of which are:…”

Room-temperature X-ray response of cadmium–zinc–telluride pixel detectors grown by the vertical Bridgman technique

“…As well documented in the literature (Bolotnikov et al, 2005;Guerra et al, 2008), sub-millimetre CZT pixel detectors typically suffer from charge sharing and cross-talk distortions. These phenomena mainly occur in the region near the interpixel gaps of the detector arrays.…”

Spectral correction algorithm for multispectral CdTe x-ray detectors

“…The latter distortion arises from many factors, and using the descriptions in Ref. 11, 12, 14 they can be explained as follows:…”

“…We use the Multix ME100 v2 CdTe detector to develop and test the algorithm. The algorithm corrects the spectra for the well described effects of charge sharing, weighting potential cross talk, pulse pileup, and escape peaks, 11,12 which we correct by making models based on the physical origin of these detector effects. Further, we develop a model to account for a flux dependent incomplete charge collection.…”