Thallium Bromide Gamma-Ray Spectrometers and Pixel Arrays

Kim, Hadong; Ogorodnik, Y. V.; Kargar, Alireza; Cirignano, L.; Thrall, Crystal L.; Koehler, W. F.; O’Neal, Sean; He, Zhong; Swanberg, E.; Payne, Stephen A.; Squillante, Michael R.; Shah, K.S.

doi:10.3389/fphy.2020.00055

Cited by 19 publications

(13 citation statements)

References 34 publications

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“…A CCI TlBr device operated in coincidence with a reference detector achieved a CTR of 330 ps FWHM by reading out theČerenkov light. It is expected that CCI TlBr detectors achieve an energy resolution comparable to state-of-the-art TlBr devices only using charge induction readout, namely, ∼1.5% at 662 keV [14]. Arrays with 1-mm pixel pitch have shown DOI accuracy down to 1 mm [15].…”

Section: Introductionmentioning

confidence: 99%

Study of Čerenkov Light Emission in the Semiconductors TlBr and TlCl for TOF-PET

Ariño‐Estrada

Roncali

et al. 2021

IEEE Trans. Radiat. Plasma Med. Sci.

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Thallium bromide (TlBr) and thallium chloride (TlCl) are semiconductor materials with high transparency to visible light, a high index of refraction, and high detection efficiency for gamma rays and annihilation photons. This manuscript reports on measurements of the light intensity and timing response ofČerenkov light emitted in one 3 mm × 3 mm × 5 mm slab of each of these materials operated in coincidence with a lutetium fine silicate (LFS) crystal with dimensions of 3 mm × 3 mm × 20 mm. A 22 Na radioactive source was used. The measured average number of detected photons per event was 1.5 photons for TlBr and 2.8 photons for TlCl when these materials were coupled to a silicon photomultiplier. The simulation predicts these results with an overestimation of 12%. The best coincidence time resolution (CTR) for events in TlBr and TlCl was 329 ± 9 and 316 ± 9 ps, respectively, when events with four photons and >7 photons were selected. The simulation showed the CTR degraded from 120 to 405 ps in TlCl, and from 160 to 700 ps in TlBr when the first or sec-ondČerenkov photon was selected. Results of this work show that TlCl has a strongerČerenkov light emission compared to TlBr and a greater potential to obtain the best timing measurements. Results also stress the importance of improving detection efficiency and transport of light to capture the firstČerenkov photon in timing measurements. Index Terms-Čerenkov charge induction (CCI) detectors, Cerenkov light, fast timing, thallium bromide (TlBr), thallium chloride (TlCl), time-of-flight positron emission tomography (TOF-PET).

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Section: Introductionmentioning

confidence: 99%

Study of Čerenkov Light Emission in the Semiconductors TlBr and TlCl for TOF-PET

Ariño‐Estrada

Roncali

et al. 2021

IEEE Trans. Radiat. Plasma Med. Sci.

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“…A possible alternative for finely-pixelated CZT detectors are Thallium Bromide (TlBr) detectors. The high atomic number of Thallium (81) make TlBr more efficient for photoelectric interactions than CZT, and Kim et al (2020) report sub-1% energy resolutions. Germanium based Charge Coupled Devices (Ge-CCDs) may be another competitor, but still suffer from yield issues (Leitz et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Cadmium Zinc Telluride Detectors for a Next-Generation Hard X-ray Telescope

Tang,

Kislat,

Krawczynski

2021

Preprint

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We are currently developing Cadmium Zinc Telluride (CZT) detectors for a next-generation space-borne hard X-ray telescope which can follow up on the highly successful NuSTAR (Nuclear Spectroscopic Telescope Array) mission. Since the launch of NuSTAR in 2012, there have been major advances in the area of X-ray mirrors, and state-of-the-art X-ray mirrors can improve on NuSTAR's angular resolution of ∼1 arcmin Half Power Diameter (HPD) to 15 or even 5 HPD. Consequently, the size of the detector pixels must be reduced to match this resolution. This paper presents detailed simulations of relatively thin (1 mm thick) CZT detectors with hexagonal pixels at a next-neighbor distance of 150 µm. The simulations account for the non-negligible spatial extent of the deposition of the energy of the incident photon, and include detailed modeling of the spreading of the free charge carriers as they move toward the detector electrodes. We discuss methods to reconstruct the energies of the incident photons, and the locations where the photons hit the detector. We show that the charge recorded in the brightest pixel and six adjacent pixels suffices to obtain excellent energy and spatial resolutions. The simulation results are being used to guide the design of a hybrid application-specific integrated circuit (ASIC)-CZT detector package.

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“…Energy resolutions for TlBr detectors have also been reported as 6.4% at 511 keV on less than 1 mm thick detectors [52]. Additionally, 5 mm thick TlBr detectors have been shown to have 2.85% ± 0.88% at 662 keV [63].…”

Section: Semiconductor Detectorsmentioning

confidence: 97%

State-of-the-art challenges and emerging technologies in radiation detection for nuclear medicine imaging: A review

Enlow

Abbaszadeh

2023

Front. Phys.

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Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are established medical imaging modalities that have been implemented for decades, but improvements in detector design and camera electronics are needed for advancement of both imaging technologies. Detectors are arguably the most important aspect of the systems. Similar to SPECT, PET typically relies on indirect conversion of gamma radiation via scintillators coupled with photosensors used to convert optical photons produced by the scintillator into an electrical signal. PET detectors are defined by their energy resolution, timing resolution, and spatial resolution, all of which affect and determine the image quality. Improvements in energy resolution have been shown by increasing the brightness of the scintillator utilizing materials like cerium bromide (CeBr3) or switching to a direct conversion detector, such as cadmium zinc telluride (CZT) or thallium bromide (TlBr). Timing resolution for PET is a focal point of the current research. Improving the timing resolution improves the signal-to-noise of the PET system and is integral to the implementation of time-of-flight PET. By utilizing novel configurations, such as side readouts on scintillators, timing resolution has been improved dramatically. Similarly, metascintillators, which use complex combinations for the scintillator material, have also shown improvements to the timing resolution. Additional research has focused on using Cherenkov light emission in scintillators to further improve the timing resolution. Other research is focused on using convolutional neural networks and other signal processing to enhance timing resolution. Lastly, aside from acollinearity and positron range, spatial resolution is impacted by the PET detector, therefore improving the intrinsic spatial resolution of the detector will allow for smaller features to be imaged. One method for improving the spatial resolution is to use unique configurations with layered scintillators. Additionally, monolithic scintillators have also been shown to have reduced spatial resolution. The future for both SPECT and PET image system advancement will depend on continued development of the detectors via many different pathways including materials, signal processing, physics, and novel configurations. In this review article, we will discuss challenges and emerging technologies for state-of-the-art radiation detectors utilized in PET and SPECT.

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Thallium Bromide Gamma-Ray Spectrometers and Pixel Arrays

Cited by 19 publications

References 34 publications

Study of Čerenkov Light Emission in the Semiconductors TlBr and TlCl for TOF-PET

Study of Čerenkov Light Emission in the Semiconductors TlBr and TlCl for TOF-PET

Cadmium Zinc Telluride Detectors for a Next-Generation Hard X-ray Telescope

State-of-the-art challenges and emerging technologies in radiation detection for nuclear medicine imaging: A review

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