Time walk correction of CdTe detectors using depth sensing technique

Nakhostin, M.; Walker, P. M.; Sellin, P.J.

doi:10.1016/j.nima.2010.05.033

Cited by 10 publications

(6 citation statements)

References 19 publications

(11 reference statements)

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“…By compensating the electron drift time, the timing resolution of CdZnTe detector could potentially be further improved using the depth sensing technique [23]. This would be very important for coincidence detection when CdZnTe detector is used for PET imaging application.…”

Section: Resultsmentioning

confidence: 99%

3-D Spatial Resolution of 350 $\mu$m Pitch Pixelated CdZnTe Detectors for Imaging Applications

Yin

Chen

et al. 2013

IEEE Trans. Nucl. Sci.

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We are currently investigating the feasibility of using highly pixelated Cadmium Zinc Telluride (CdZnTe) detectors for sub-500 μm resolution PET imaging applications. A 20 mm × 20 mm × 5 mm CdZnTe substrate was fabricated with 350 μm pitch pixels (250 μm anode pixels with 100 μm gap) and coplanar cathode. Charge sharing among the pixels of a 350 μm pitch detector was studied using collimated 122 keV and 511 keV gamma ray sources. For a 350 μm pitch CdZnTe detector, scatter plots of the charge signal of two neighboring pixels clearly show more charge sharing when the collimated beam hits the gap between adjacent pixels. Using collimated Co-57 and Ge-68 sources, we measured the count profiles and estimated the intrinsic spatial resolution of 350 μm pitch detector biased at −1000 V. Depth of interaction was analyzed based on two methods, i.e., cathode/anode ratio and electron drift time, in both 122 keV and 511 keV measurements. For single-pixel photopeak events, a linear correlation between cathode/anode ratio and electron drift time was shown, which would be useful for estimating the DOI information and preserving image resolution in CdZnTe PET imaging applications.

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Section: Resultsmentioning

confidence: 99%

3-D Spatial Resolution of 350 $\mu$m Pitch Pixelated CdZnTe Detectors for Imaging Applications

Yin

Chen

et al. 2013

IEEE Trans. Nucl. Sci.

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“…These measurements suggested that CZT has a time resolution on the order of a few nanoseconds and can be improved by using digital signal processing. [8,9] Du et al [10] have suggested that the temporal response of CZT may be unstable under intense irradiation. Bale et al [11] reported the lateral polarization effect generated in CZT detectors, which were fabricated from crystals with low hole transport properties, due to the hole trapping when exposed to the continuous high-flux x-rays.…”

Section: Introductionmentioning

confidence: 99%

Temporal pulsed x-ray response of CdZnTe: In detector

Guo¹,

Ye²,

Zha³

et al. 2018

Chinese Phys. B

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The temporal response of cadmium-zinc-telluride (CZT) crystals is evaluated at room temperature by using an ultrafast-pulsed x-ray source. The dynamics of carrier relaxation in a CZT single crystal is modeled at a microscopic level based on a multi-trapping effect. The effects of the irradiation flux and bias voltage on the amplitude and full width at half maximum (FWHM) of the transient currents are investigated. It is demonstrated that the temporal response process is affected by defect level occupation fraction. A fast photon current can be achieved under intense pulsed x-ray irradiation to be up to 2.78×10 9 photons mm −2 •s −1 . Meanwhile, it is found that high bias voltage could enhance carrier detrapping by suppressing the capture of structure defects and thus improve the temporal response of CZT detectors.

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“…Moreover, the spectroscopic performance of compound semiconductor detectors is still limited by the charge-trapping effect (Eisen et al 1999). Studies have suggested that, in principle, the timing and spectroscopic performances of the detectors can be improved by using the information in the shape of output pulses (Meng and He 2005, Mitchell et al 2008, Nakhostin et al 2010. However, the common front-end electronic systems based on analog application specific integrated circuits (ASICs) offer very limited flexibility to exploit the information in the shape of pulses.…”

Section: Introductionmentioning

confidence: 99%

Optimizing timing performance of CdTe detectors for PET

Nakhostin¹

2017

Phys. Med. Biol.

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Despite several attractive properties, the poor timing performance of compound semiconductor detectors such as CdTe and CdZnTe has hindered their use in commercial PET imaging systems. The standard method of pulse timing with such detectors is to employ a constant-fraction discriminator at the output of a timing filter which is fed by the pulses from a charge-sensitive preamplifier. The method has led to a time resolution of about 10 ns at full-width at half-maximum (FWHM) with 1 mm thick CdTe detectors. This paper presents a detailed investigation on the parameters limiting the timing performance of Ohmic contact planar CdTe detectors with the standard pulse timing method. The jitter and time-walk errors are studied through simulation and experimental measurements and it is revealed that the best timing results obtained with the standard timing method suffer from a significant loss of coincidence events (~50%). In order to improve the performance of the detectors with full detection efficiency, a new digital pulse timing method based on a simple pattern recognition technique was developed. A time resolution of 3.29 ± 0.10 ns (FWHM) in the energy range of 300-650 keV was achieved with an Ohmic contact planar CdTe detector (5 × 5 × 1 mm). The digital pulse processing method was also used to correct for the charge-trapping effect and an improvement in the energy resolution from 4.83 ± 0.66% to 2.780 ± 0.002% (FWHM) at 511 keV was achieved. Further improvement of time resolution through a moderate cooling of the detector and the application of the method to other detector structures are also discussed.

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Time walk correction of CdTe detectors using depth sensing technique

Cited by 10 publications

References 19 publications

3-D Spatial Resolution of 350 $\mu$m Pitch Pixelated CdZnTe Detectors for Imaging Applications

3-D Spatial Resolution of 350 $\mu$m Pitch Pixelated CdZnTe Detectors for Imaging Applications

Temporal pulsed x-ray response of CdZnTe: In detector

Optimizing timing performance of CdTe detectors for PET

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