Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis

Meng, Ling-Jian; He, Zhong

doi:10.1016/j.nima.2005.04.076

Cited by 39 publications

(35 citation statements)

References 7 publications

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“…The time taken by electrons to drift through the entire detector thickness can be accurately determined using pulse waveform analysis [10], [11]. A typical cathode pulse waveform is shown in Fig.…”

Section: B Electron Mobility and Lifetime Measurementsmentioning

confidence: 99%

Spectroscopic performance of thick HgI/sub 2/ detectors

Meng

Alexander

et al. 2006

IEEE Trans. Nucl. Sci.

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This paper presents the spectroscopic performance of two newly developed pixelated HgI 2 detectors. These detectors are 1 × 1 × 0.814 cm 3 and 1 × 1 × 1.016 cm 3 in size. Each detector has four closely packed 1 × mm 2 anode pixels at the center of one of the 1 × 1 cm 2 surfaces. These anode pixels are surrounded by a large anode. All results presented here are based on events from a sub-volume underneath the anode pixels. In these detectors, signals were read out by a discrete electronics based on multiple A-250 pre-amplifiers and a digital oscilloscope for sampling pulse waveforms. Depth sensing technique was used to correct the depth-dependent variation in photopeak amplitude. Main results presented are: (1) energy resolutions of 0.85 ~ 1.3% have been achieved on these detectors; (2) the electron mobility-lifetime product was measured to be ~1 × 10 −2 cm 2 /V and the measured electron lifetime was ~200 μs and (3) variation in electron drifting properties under different anode pixels were observed. Significant non-uniformity in internal electric field strength was also experimentally demonstrated.

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Section: B Electron Mobility and Lifetime Measurementsmentioning

confidence: 99%

Spectroscopic performance of thick HgI/sub 2/ detectors

Meng

Alexander

et al. 2006

IEEE Trans. Nucl. Sci.

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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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“…The result is that CZT detectors have more timing jitter and time walk, which degrades the coincidence time resolution. Meng and He (2005) have shown that time resolution of ~10 ns may be achieved if the full waveform from each event were digitized for analysis. However, our RENA-3 based data acquisition system does not enable this as it samples only the pulse peak value, and uses a leading edge discriminator for time pick-off.…”

Section: Discussionmentioning

confidence: 99%

Study of electrode pattern design for a CZT-based PET detector

Gu¹,

Levin²

2014

Phys. Med. Biol.

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We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3-D positioning Cadmium Zinc Telluride (CZT) photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 mm and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 ns to ~127.5 ns FWHM for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 ns to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger “small pixel” effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 V to −80 V w.r.t the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 μm vs. 100 μm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

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Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis

Cited by 39 publications

References 7 publications

Spectroscopic performance of thick HgI/sub 2/ detectors

Spectroscopic performance of thick HgI/sub 2/ detectors

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

Study of electrode pattern design for a CZT-based PET detector

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