Monte Carlo investigation of charge‐transport effects on energy resolution and detection efficiency of pixelated CZT detectors for SPECT/PET applications

Myronakis, Marios; Darambara, Dimitra G.

doi:10.1118/1.3532825

Cited by 40 publications

(39 citation statements)

References 33 publications

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“…The first is the increased overall thickness achieved, leading to improved PET statistics without the need to grow a thicker CdZnTe crystal. The second advantage is the impact on the induced signal from the charge transport effects which is less in detectors with 1 mrn pixel size and 0.5 cm thickness than in thicker detectors with the same pixel size [7]. The third is the use of the first detector in each stack to perform SPECT imaging using conventional collimator (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…1), whereas at 140 keY a detector with thickness equal to 0.5 cm is enough to obtain detection efficiency greater than 90%. Based on previous work from our team [7], [9] we designed PET/SPECT systems composed of detector stacks arranged in cylindrical fashion. Each stack has seven detectors with thickness of 0.5 cm and pixel size equal to 1.0 mm (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Computational models of the imaging systems were constructed using a unique modeling framework developed by our team [7], [8]. The aim of the project is the design of an integrated breast-specific PET/SPECT imaging system that could be further integrated with DBT, CT or MR.…”

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confidence: 99%

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Integrated PET/SPECT system for breast imaging with CdZnTe: Computational assessment

Myronakis

Zvelebil

Darambara

2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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Breast specific gamma-ray imaging is gaining research attention as a mean to improve lesion detectability and patient management. Multimodality imaging is currently a hot topic of research with a gradually increasing number of systems installed in hospitals and new trends such as PET/MR and SPECT/MR. Cadmium Zinc Telluride (CdZnTe) pixelated detectors have the potential to lead in both these trends, allowing the design of flexible systems that can perform PET and SPECTimaging with the same detector material whereas being compact enough to be integrated with current MR systems. In the current study, the computational models of integrated PET/SPECT systems employing pixelated CdZnTe detectors in a stacked arrangement to achieve high detection efficiency were assessed in terms of spatial resolution. In addition to classic collimators for SPECT imaging, the possibility for electronic collimation is also investigated to greatly enhance the flexibility of the system. The models were constructed using a unique and realistic modeling framework that accurately handles charge transport effects in the detector and particle interactions in the system. Current preliminary results for PET imaging suggest that sub-centimeter resolution can be achieved.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Integrated PET/SPECT system for breast imaging with CdZnTe: Computational assessment

Myronakis

Zvelebil

Darambara

2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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“…The small pixel effect can be seen clearly in the vicinity of the pixel's anode. Right: the correlation between weighting potential and interaction distance from the anode [41] (Image courtesy of American Association of Physicists in Medicine).…”

Section: Figurementioning

confidence: 99%

Progress in the Development of CdZnTe Unipolar Detectors for Different Anode Geometries and Data Corrections

Zhang

et al. 2013

Sensors

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CdZnTe detectors have been under development for the past two decades, providing good stopping power for gamma rays, lightweight camera heads and improved energy resolution. However, the performance of this type of detector is limited primarily by incomplete charge collection problems resulting from charge carriers trapping. This paper is a review of the progress in the development of CdZnTe unipolar detectors with some data correction techniques for improving performance of the detectors. We will first briefly review the relevant theories. Thereafter, two aspects of the techniques for overcoming the hole trapping issue are summarized, including irradiation direction configuration and pulse shape correction methods. CdZnTe detectors of different geometries are discussed in detail, covering the principal of the electrode geometry design, the design and performance characteristics, some detector prototypes development and special correction techniques to improve the energy resolution. Finally, the state of art development of 3-D position sensing and Compton imaging technique are also discussed. Spectroscopic performance of CdZnTe semiconductor detector will be greatly improved even to approach the statistical limit on energy resolution with the combination of some of these techniques.

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“…20 The development of a semiconductor based photon counting detector for breast CT is very challenging with a number of factors contributing to the degradation of image quality including characteristic x-rays, 21 trapping, and spreading of charge as it propagates to the detector elements, [22][23][24][25] pulsepileup, 26,27 and inhomogeneity in response between detector elements among others. Of these factors, the degradation of characteristic x-rays is an inherent phenomena in cadmium zinc telluride (CZT) that will always be present and cannot be reduced regardless of detector operating parameters (e.g., charge sharing can be reduced with increased bias voltage, pulse pileup can be reduced by lower the input flux etc.).…”

Section: Introductionmentioning

confidence: 99%

Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions

Glick

Didier²

2013

Journal of Applied Physics

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A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5-3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 lm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 lm and lower kV settings. Characteristic x-rays produced increasing distortion in the spectral response with decreasing detector element size.

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Monte Carlo investigation of charge‐transport effects on energy resolution and detection efficiency of pixelated CZT detectors for SPECT/PET applications

Cited by 40 publications

References 33 publications

Integrated PET/SPECT system for breast imaging with CdZnTe: Computational assessment

Integrated PET/SPECT system for breast imaging with CdZnTe: Computational assessment

Progress in the Development of CdZnTe Unipolar Detectors for Different Anode Geometries and Data Corrections

Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions

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