Effects of charge sharing in 3-D position sensitive CdZnTe gamma-ray spectrometers

He, Zhong; Li, W.; Knoll, G.F.; Wehe, D.K.; Du, Yuzhe

doi:10.1016/s0168-9002(99)00841-4

Cited by 25 publications

(11 citation statements)

References 6 publications

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“…Similar studies have been done by other groups with pixel detectors. Du et al [6] and He et al [7] investigated charge charing in 3-D position sensitive CdZnTe spectrometers and obtained sizes of electron clouds for different gamma-ray sources. Bolotnikov et al [8] studied the charge loss to inter-pixel gaps.…”

Section: Introductionmentioning

confidence: 99%

Investigation of charge sharing among electrode strips for a CdZnTe detector

Kalemci

Matteson

2002

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Introductionmentioning

confidence: 99%

Investigation of charge sharing among electrode strips for a CdZnTe detector

Kalemci

Matteson

2002

Nuclear Instruments and Methods in Physics Research Section A:

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“…For example, significant charge sharing was reported in CdZnTe pixel (Gaskin et al 2003, He et al 2000) and strip detectors (Kalemci and Matteson 2002) with pitches, crystal thicknesses and bias voltages similar to the photon-counting detector used in this study. On the other hand, significant charge sharing was also observed in a CdTe pixel detector with a 55 µm pitch (Maiorino et al 2006, Pennicard et al 2009).…”

Section: Resultsmentioning

confidence: 62%

MicroCT with energy-resolved photon-counting detectors

Meier

Mikkelsen

et al. 2011

Phys. Med. Biol.

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The goal of this paper was to investigate the benefits that could be realistically achieved on a microCT imaging system with an energy-resolved photon-counting x-ray detector. To this end, we built and evaluated a prototype microCT system based on such a detector. The detector is based on cadmium telluride (CdTe) radiation sensors and application-specific integrated circuit (ASIC) readouts. Each detector pixel can simultaneously count x-ray photons above six energy thresholds, providing the capability for energy-selective x-ray imaging. We tested the spectroscopic performance of the system using polychromatic x-ray radiation and various filtering materials with Kabsorption edges. Tomographic images were then acquired of a cylindrical PMMA phantom containing holes filled with various materials. Results were also compared with those acquired using an intensity-integrating x-ray detector and single-energy (i.e. non-energy-selective) CT. This paper describes the functionality and performance of the system, and presents preliminary spectroscopic and tomographic results. The spectroscopic experiments showed that the energy-resolved photon-counting detector was capable of measuring energy spectra from polychromatic sources like a standard x-ray tube, and resolving absorption edges present in the energy range used for imaging. However, the spectral quality was degraded by spectral distortions resulting from degrading factors, including finite energy resolution and charge sharing. We developed a simple charge-sharing model to reproduce these distortions. The tomographic experiments showed that the availability of multiple energy thresholds in the photon-counting detector allowed us to simultaneously measure target-to-background contrasts in different energy ranges. Compared with single-energy CT with an integrating detector, this feature was especially useful to improve differentiation of materials with different attenuation coefficient energy dependences.

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“…Alternatively, sophisticated processing of events that involve multiple anode pixels may allow one to utilize all events detected by small anode pixel CdZnTe detectors for imaging purposes. Although the characteristics of the CdZnTe detectors have been widely investigated over the last decade (Bolotnikov et al 1999, He et al 2000, Meng and He 2005), little has been reported about CdZnTe as a PET detector (Vaska et al 2007, Gu et al 2011) and we did not find any publication about a CdZnTe PET detector with anode pixel size less than 0.5 mm.…”

Section: Introductionmentioning

confidence: 76%

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications

Komarov

Yin

et al. 2012

Phys. Med. Biol.

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We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 μm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 μm in x,y-plane and ~0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 μm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 μm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods.

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Effects of charge sharing in 3-D position sensitive CdZnTe gamma-ray spectrometers

Cited by 25 publications

References 6 publications

Investigation of charge sharing among electrode strips for a CdZnTe detector

Investigation of charge sharing among electrode strips for a CdZnTe detector

MicroCT with energy-resolved photon-counting detectors

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications

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