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Singh P, Dosovitskiy G, Bekenstein Y. Bright Innovations: Review of Next-Generation Advances in Scintillator Engineering. ACS NANO 2024; 18:14029-14049. [PMID: 38781034 PMCID: PMC11155248 DOI: 10.1021/acsnano.3c12381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 04/28/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024]
Abstract
This review focuses on modern scintillators, the heart of ionizing radiation detection with applications in medical diagnostics, homeland security, research, and other areas. The conventional method to improve their characteristics, such as light output and timing properties, consists of improving in material composition and doping, etc., which are intrinsic to the material. On the contrary, we review recent advancements in cutting-edge approaches to shape scintillator characteristics via photonic and metamaterial engineering, which are extrinsic and introduce controlled inhomogeneity in the scintillator's surface or volume. The methods to be discussed include improved light out-coupling using photonic crystal (PhC) coating, dielectric architecture modification producing the Purcell effect, and meta-materials engineering based on energy sharing. These approaches help to break traditional bulk scintillators' limitations, e.g., to deal with poor light extraction efficiency from the material due to a typically large refractive index mismatch or improve timing performance compared to bulk materials. In the Outlook section, modern physical phenomena are discussed and suggested as the basis for the next generations of scintillation-based detectors and technology, followed by a brief discussion on cost-effective fabrication techniques that could be scalable.
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Affiliation(s)
- Pallavi Singh
- Solid
State Institute, Technion-Israel Institute
of Technology, Haifa 32000, Israel
| | - Georgy Dosovitskiy
- Solid
State Institute, Technion-Israel Institute
of Technology, Haifa 32000, Israel
| | - Yehonadav Bekenstein
- Solid
State Institute, Technion-Israel Institute
of Technology, Haifa 32000, Israel
- Department
of Materials Science and Engineering, Technion-Israel
Institute of Technology, Haifa 32000, Israel
- The
Nancy and Stephen Grand Technion Energy Program, Technion-Israel Institute of Technology, 32000 Haifa, Israel
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2
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Piller M, Castilla AM, Terragni G, Alozy J, Auffray E, Ballabriga R, Campbell M, Deutschmann B, Gascon D, Gola A, Merzi S, Michalowska-Forsyth A, Penna M, Gómez S, Kratochwil N. Performance evaluation of the FastIC readout ASIC with emphasis on Cherenkov emission in TOF-PET. Phys Med Biol 2024; 69:115014. [PMID: 38657637 DOI: 10.1088/1361-6560/ad42fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 04/24/2024] [Indexed: 04/26/2024]
Abstract
Objective.The efficient usage of prompt photons like Cherenkov emission is of great interest for the design of the next generation, cost-effective, and ultra-high-sensitivity time-of-flight positron emission tomography (TOF-PET) scanners. With custom, high power consuming, readout electronics and fast digitization the prospect of sub-300 ps FWHM with PET-sized BGO crystals have been shown. However, these results are not scalable to a full system consisting of thousands of detector elements.Approach.To pave the way toward a full TOF-PET scanner, we examine the performance of the FastIC ASIC with Cherenkov-emitting scintillators (BGO), together with one of the most recent SiPM detector developments based on metal trenching from FBK. The FastIC is a highly configurable ASIC with 8 input channels, a power consumption of 12 mW ch-1and excellent linearity on the energy measurement. To put the timing performance of the FastIC into perspective, comparison measurements with high-power consuming readout electronics are performed.Main results.We achieve a best CTR FWHM of 330 ps for 2 × 2 × 3 mm3and 490 ps for 2 × 2 × 20 mm3BGO crystals with the FastIC. In addition, using 20 mm long LSO:Ce:Ca crystals, CTR values of 129 ps FWHM have been measured with the FastIC, only slightly worse to the state-of-the-art of 95 ps obtained with discrete HF electronics.Significance.For the first time, the timing capability of BGO with a scalable ASIC has been evaluated. The findings underscore the potential of the FastIC ASIC in the development of cost-effective TOF-PET scanners with excellent timing characteristics.
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Affiliation(s)
- Markus Piller
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
- Graz University of Technology, Institute of Electronics, A-8010 Graz, Austria
| | | | - Giulia Terragni
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
- Technical University of Vienna, Austria
| | - Jerome Alozy
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
| | | | - Rafael Ballabriga
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
- University of Barcelona, Spain
| | | | - Bernd Deutschmann
- Graz University of Technology, Institute of Electronics, A-8010 Graz, Austria
| | | | - Alberto Gola
- Fondazione Bruno Kessler, Via Sommarive, 18 I-38123, Trento, Italy
| | - Stefano Merzi
- Fondazione Bruno Kessler, Via Sommarive, 18 I-38123, Trento, Italy
| | | | - Michele Penna
- Fondazione Bruno Kessler, Via Sommarive, 18 I-38123, Trento, Italy
| | - Sergio Gómez
- University of Barcelona, Spain
- Serra Hunter Fellow at Polytechnic University of Catalonia, Spain
| | - Nicolaus Kratochwil
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
- Department of Biomedical Engineering, University of California, Davis, United States of America
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Yi M, Ko GB, Lee JS. Pushing the limit of BGO-based dual-ended Cherenkov PET detectors through photon transit time correction. Phys Med Biol 2024; 69:025005. [PMID: 38091614 DOI: 10.1088/1361-6560/ad1549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/13/2023] [Indexed: 01/06/2024]
Abstract
Objective. The high production cost of commonly used lutetium-based fast scintillators and the development of silicon photomultipliers technology have made bismuth germanate (BGO) a promising candidate for time-of-flight positron emission tomography (TOF PET) detectors owing to its generation of prompt Cherenkov photons. However, using BGO as a hybrid scintillator is disadvantageous owing to its low photon statistics and distribution that does not conform well to a single Gaussian. To mitigate this, a proposal was made to increase the likelihood of detecting the first Cherenkov photons by positioning two photosensors in opposition at the entrance and exit faces of the scintillator and subsequently selectively picking an earlier timestamp. Nonetheless, the timing variation arising from the photon transit time remains affected by the entire length of the crystal, thereby presenting a possibility for further enhancement.Approach. In this study, we aimed to improve the timing performance of the dual-ended BGO Cherenkov TOF PET detector by capitalizing on the synergistic advantages of applying depth-of-interaction (DOI) information and crystal surface finishes or reflector properties. A dual-ended BGO detector was implemented using a 3 × 3 × 15 mm3BGO crystal. Coincidence events were acquired against a 3 × 3 × 3 mm3LYSO:Ce:Mg reference detector. The timing performance of the dual-ended BGO detectors was analyzed using conventionally proposed timestamp methods before and after DOI correction.Results. Through a DOI-based correction of photon transit time spread, we demonstrated a further improvement in the timing resolution of the BGO-based Cherenkov TOF PET detector utilizing a dual-ended detector configuration and adaptive arrival time pickoff. We achieved further improvements in timing resolution by correcting the offset spread induced by the fluctuation of timing signal rise time in the dual-ended detector.Significance. Although polishing the crystal surface was still favorable in terms of full-width-half-maximum value, incorporating DOI information from the unpolished crystal to compensate for photon travel time facilitated additional enhancement in the overall timing performance, thereby surpassing that achieved with the polished crystal.
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Affiliation(s)
- Minseok Yi
- Interdisciplinary Program in Bioengineering, College of Engineering, Seoul National Graduate School, Seoul, Republic of Korea
- Department of Nuclear Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Integrated Major in Innovative Medical Science, Seoul National Graduate School, Seoul, Republic of Korea
| | - Guen Bae Ko
- Brightonix Imaging Inc., Seoul, Republic of Korea
- Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae Sung Lee
- Interdisciplinary Program in Bioengineering, College of Engineering, Seoul National Graduate School, Seoul, Republic of Korea
- Department of Nuclear Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
- Integrated Major in Innovative Medical Science, Seoul National Graduate School, Seoul, Republic of Korea
- Brightonix Imaging Inc., Seoul, Republic of Korea
- Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine, Seoul, Republic of Korea
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4
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Nadig V, Hornisch M, Oehm J, Herweg K, Schulz V, Gundacker S. 16-channel SiPM high-frequency readout with time-over-threshold discrimination for ultrafast time-of-flight applications. EJNMMI Phys 2023; 10:76. [PMID: 38044383 PMCID: PMC10694125 DOI: 10.1186/s40658-023-00594-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023] Open
Abstract
BACKGROUND Over the past five years, ultrafast high-frequency (HF) readout concepts have advanced the timing performance of silicon photomultipliers (SiPMs). The shown impact in time-of-flight (TOF) techniques can further push the limits in light detection and ranging (LiDAR), time-of-flight positron-emission tomography (TOF-PET), time-of-flight computed tomography (TOF-CT) or high-energy physics (HEP). However, upscaling these electronics to a system-applicable, multi-channel readout, has remained a challenging task, posed by the use of discrete components and a high power consumption. To this day, there are no means to exploit the high TOF resolution of these electronics on system scale or to measure the actual timing performance limits of a full detector block. METHODS In this work, we present a 16-channel HF readout board, including leading-edge discrimination and a linearized time-over-threshold (TOT) method, which is fully compatible with a high-precision time-to-digital converters (TDCs), such as the picoTDC developed at CERN. The discrete implementation allows ideal adaptation of this readout to a broad range of detection tasks. As a first step, the functionality of the circuit has been tested using the TOFPET2 ASIC as back-end electronics to emulate the TDC, also in view of its properties as a highly scalable data acquisition solution. RESULTS The produced board is able to mitigate influences of baseline shifts in the TOFPET2 front end, which has been shown in experiments with a pulsed laser, increasing the achievable intrinsic coincidence timing resolution (CTR) of the TOFPET2 readout electronics from 70 ps (FWHM) to 62 ps (FWHM). Single-channel coincidence experiments including a [Formula: see text]-source, 2[Formula: see text]2[Formula: see text]3 mm[Formula: see text] LYSO:Ce,Ca crystals and Broadcom NUV-MT SiPMs resulted in a CTR of 118 ps (FWHM). For a 4[Formula: see text]4 matrix of 3.88[Formula: see text]3.88[Formula: see text]19 mm[Formula: see text] LYSO:Ce,Ca crystals one-to-one coupled to a 4[Formula: see text]4 array of Broadcom NUV-MT SiPMs, an average CTR of 223 ps (FWHM) was obtained. CONCLUSION The implemented 16-channel HF electronics are fully functionall and have a negligible influence on the timing performance of the back-end electronics used, here the TOFPET2 ASIC. The ongoing integration of the picoTDC with the 16-channel HF board is expected to further set the path toward sub-100 ps TOF-PET and sub-30ps TOF resolution for single-photon detection.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Matthias Hornisch
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Jakob Oehm
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Katrin Herweg
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, Pauwelsstraße 19, 52074, Aachen, Germany
- III. Physikalisches Institut B, RWTH Aachen University, Otto-Blumenthal-Straße, 52074, Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, Forckenbeckstraße 55, 52074, Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstraße 55, 52074, Aachen, Germany.
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Loignon-Houle F, Toussaint M, Bertrand É, Lemyre FC, Lecomte R. Timing Estimation and Limits in TOF-PET Detectors Producing Prompt Photons. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2023; 7:692-703. [PMID: 38156329 PMCID: PMC10751813 DOI: 10.1109/trpms.2023.3279455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2023]
Abstract
The production of prompt photons providing high photon time densities is a promising avenue to reach ultrahigh coincidence time resolution (CTR) in time-of-flight PET. Detectors producing prompt photons are receiving high interest experimentally, ignited by past exploratory theoretical studies that have anchored some guiding principles. Here, we aim to consolidate and extend the foundations for the analytical modeling of prompt generating detectors. We extend the current models to a larger range of prompt emission kinetics where more stringent requirements on the prompt photon yield rapidly emerge as a limiting factor. Lower bound and estimator evaluations are investigated with different underlying models, notably by merging or keeping separate the prompt and scintillation photon populations. We further show the potential benefits of knowing the proportion of prompt photons within a detection set to improve the CTR by mitigating the detrimental effect of population (prompt vs scintillation) mixing. Taking into account the fluctuations on the average number of detected prompt photons in the model reveals a limited influence when prompt photons are accompanied by fast scintillation (e.g., LSO:Ce:Ca) but a more significant effect when accompanied by slower scintillation (e.g., BGO). Establishing performance characteristics and limitations of prompt generating detectors is paramount to gauging and targeting the best possible timing capabilities they can offer.
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Affiliation(s)
- Francis Loignon-Houle
- Sherbrooke Molecular Imaging Center of CRCHUS and with the Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada, currently with Instituto de Instrumentación para Imagen Molecular, Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - Maxime Toussaint
- Sherbrooke Molecular Imaging Center of CRCHUS and with the Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Émilie Bertrand
- CRCHUS and with the Department of Mathematics, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Félix Camirand Lemyre
- CRCHUS and with the Department of Mathematics, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Roger Lecomte
- Sherbrooke Molecular Imaging Center of CRCHUS and with the Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada, and also with IR&T Inc., Sherbrooke, QC, Canada
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6
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Gundacker S, Borghi G, Cherry SR, Gola A, Lee D, Merzi S, Penna M, Schulz V, Kwon SI. On timing-optimized SiPMs for Cherenkov detection to boost low cost time-of-flight PET. Phys Med Biol 2023; 68:165016. [PMID: 37467766 PMCID: PMC10410404 DOI: 10.1088/1361-6560/ace8ee] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/10/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Objective.Recent SiPM developments and improved front-end electronics have opened new doors in TOF-PET with a focus on prompt photon detection. For instance, the relatively high Cherenkov yield of bismuth-germanate (BGO) upon 511 keV gamma interaction has triggered a lot of interest, especially for its use in total body positron emission tomography (PET) scanners due to the crystal's relatively low material and production costs. However, the electronic readout and timing optimization of the SiPMs still poses many questions. Lab experiments have shown the prospect of Cherenkov detection, with coincidence time resolutions (CTRs) of 200 ps FWHM achieved with small pixels, but lack system integration due to an unacceptable high power uptake of the used amplifiers.Approach.Following recent studies the most practical circuits with lower power uptake (<30 mW) have been implemented and the CTR performance with BGO of newly developed SiPMs from Fondazione Bruno Kessler tested. These novel SiPMs are optimized for highest single photon time resolution (SPTR).Main results.We achieved a best CTR FWHM of 123 ps for 2 × 2 × 3 mm3and 243 ps for 3 × 3 × 20 mm3BGO crystals. We further show that with these devices a CTR of 106 ps is possible using commercially available 3 × 3 × 20 mm3LYSO:Ce,Mg crystals. To give an insight in the timing properties of these SiPMs, we measured the SPTR with black coated PbF2of 2 × 2 × 3 mm3size. We confirmed an SPTR of 68 ps FWHM published in literature for standard devices and show that the optimized SiPMs can improve this value to 42 ps. Pushing the SiPM bias and using 1 × 1 mm2area devices we measured an SPTR of 28 ps FWHM.Significance.We have shown that advancements in readout electronics and SiPMs can lead to improved CTR with Cherenkov emitting crystals. Enabling time-of-flight with BGO will trigger a high interest for its use in low-cost and total-body PET scanners. Furthermore, owing to the prompt nature of Cherenkov emission, future CTR improvements are conceivable, for which a low-power electronic implementation is indispensable. In an extended discussion we will give a roadmap to best timing with prompt photons.
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Affiliation(s)
- Stefan Gundacker
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrae 55, D-52074 Aachen, Germany
| | - Giacomo Borghi
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
| | - Alberto Gola
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Daehee Lee
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
| | - Stefano Merzi
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
| | - Michele Penna
- Fondazione Bruno Kessler, via Sommarive 18, Trento I-38123, Italy
- Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Forckenbeckstrae 55, D-52074 Aachen, Germany
| | - Sun Il Kwon
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States of America
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Nadig V, Herweg K, Chou MMC, Lin JWC, Chin E, Li CA, Schulz V, Gundacker S. Timing advances of commercial divalent-ion co-doped LYSO:Ce and SiPMs in sub-100 ps time-of-flight positron emission tomography. Phys Med Biol 2023; 68. [PMID: 36808914 DOI: 10.1088/1361-6560/acbde4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/21/2023] [Indexed: 02/23/2023]
Abstract
Objective.Together with novel photodetector technologies and emerging electronic front-end designs, scintillator material research is one of the key aspects to obtain ultra-fast timing in time-of-flight positron emission tomography (TOF-PET). In the late 1990s, Cerium-doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) has been established as the state-of-the-art PET scintillator due to its fast decay time, high light yield and high stopping power. It has been shown that co-doping with divalent ions, such as Ca2+and Mg2+, is beneficial for its scintillation characteristics and timing performance. Therefore, this work aims to identify a fast scintillation material to combine it with novel photosensor technologies to push the state of the art in TOF-PET.Approach.This study evaluates commercially available LYSO:Ce,Ca and LYSO:Ce,Mg samples manufactured by Taiwan Applied Crystal Co., LTD regarding their rise and decay times as well as their coincidence time resolution (CTR) with both ultra-fast high-frequency (HF) readout and commercially available readout electronics, i.e. the TOFPET2 ASIC.Main results.The co-doped samples exhibit state-of-the-art rise times of on average 60 ps and effective decay times of on average 35 ns. Using the latest technological improvements made on NUV-MT SiPMs by Fondazione Bruno Kessler and Broadcom Inc., a 3 × 3 × 19 mm3LYSO:Ce,Ca crystal achieves a CTR of 95 ps (FWHM) with ultra-fast HF readout and 157 ps (FWHM) with the system-applicable TOFPET2 ASIC. Evaluating the timing limits of the scintillation material, we even show a CTR of 56 ps (FWHM) for small 2 × 2 × 3 mm3pixels. A complete overview of the timing performance obtained with different coatings (Teflon, BaSO4) and different crystal sizes coupled to standard Broadcom AFBR-S4N33C013 SiPMs will be presented and discussed.Significance.This work thoroughly evaluates commercially available co-doped LYSO:Ce crystals and, in combination with novel NUV-MT SiPMs, shows a TOF performance that significantly exceeds the current state of the art.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
| | - Katrin Herweg
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
| | | | - Jack W C Lin
- Taiwan Applied Crystal Co., LTD, Kaohsiung 80424, Taiwan
| | - Edmund Chin
- Taiwan Applied Crystal Co., LTD, Kaohsiung 80424, Taiwan
| | - Chu-An Li
- Center of Crystal Research, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
- Hyperion Hybrid Imaging Systems GmbH, D-52074 Aachen, Germany
- Physics Institute IIIB, RWTH Aachen University, D-52074 Aachen, Germany
- Fraunhofer Institute for Digital Medicine MEVIS, D-52074 Aachen, Germany
| | - Stefan Gundacker
- Department of Physics of Molecular Imaging Systems (PMI), Institute for Experimental Molecular Imaging (ExMI), RWTH Aachen University, D-52074 Aachen, Germany
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8
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He X, Trigila C, Ariño-Estrada G, Roncali E. Potential of Depth-of-Interaction-Based Detection Time Correction in Cherenkov Emitter Crystals for TOF-PET. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2023; 7:233-240. [PMID: 36994147 PMCID: PMC10042439 DOI: 10.1109/trpms.2022.3226950] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cherenkov light can improve the timing resolution of Positron Emission Tomography (PET) radiation detectors, thanks to its prompt emission. Coincidence time resolutions (CTR) of ~30 ps were recently reported when using 3.2 mm-thick Cherenkov emitters. However, sufficient detection efficiency requires thicker crystals, causing the timing resolution to be degraded by the optical propagation inside the crystal. We report on depth-of-interaction (DOI) correction to mitigate the time-jitter due to the photon time spread in Cherenkov-based radiation detectors. We simulated the Cherenkov and scintillation light generation and propagation in 3 × 3 mm2 lead fluoride, lutetium oxyorthosilicate, bismuth germanate, thallium chloride, and thallium bromide. Crystal thicknesses varied from 9 to 18 mm with a 3-mm step. A DOI-based time correction showed a 2-to-2.5-fold reduction of the photon time spread across all materials and thicknesses. Results showed that highly refractive crystals, though producing more Cherenkov photons, were limited by an experimentally obtained high-cutoff wavelength and refractive index, restricting the propagation and extraction of Cherenkov photons mainly emitted at shorter wavelengths. Correcting the detection time using DOI information shows a high potential to mitigate the photon time spread. These simulations highlight the complexity of Cherenkov-based detectors and the competing factors in improving timing resolution.
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Affiliation(s)
- Xuzhi He
- Department of Biomedical Engineering at the University of California Davis, Davis, CA 95616 USA
| | - Carlotta Trigila
- Department of Biomedical Engineering at the University of California Davis, Davis, CA 95616 USA
| | - Gerard Ariño-Estrada
- Department of Biomedical Engineering at the University of California Davis, Davis, CA 95616 USA
| | - Emilie Roncali
- Department of Biomedical Engineering at the University of California Davis, Davis, CA 95616 USA
- Department of Radiology at University of California Davis, Sacramento, CA 95817 USA
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9
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Cates JW, Choong WS. Low power implementation of high frequency SiPM readout for Cherenkov and scintillation detectors in TOF-PET. Phys Med Biol 2022; 67:195009. [PMID: 35961297 PMCID: PMC9829384 DOI: 10.1088/1361-6560/ac8963] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/07/2022] [Accepted: 08/12/2022] [Indexed: 01/25/2023]
Abstract
State-of-the-art (SoA) electronic readout for silicon photomultiplier (SiPM)-based scintillation detectors that demonstrate experimental limits in achievable coincidence time resolution (CTR) leverage low noise, high frequency signal processing to facilitate a single photon time response that is near the limit of the SiPMs architecture. This readout strategy can optimally exploit fast luminescence and prompt photon populations, and promising measurements show detector concepts employing this readout can greatly advance PET detector CTR, relative to SoA in clinical systems. However, the technique employs power hungry components which make the electronics chain impractical for channel-dense time-of-flight (TOF)-PET detectors. We have developed and tested a low noise and high frequency readout circuit which is performant at low power and consists of discrete elements with small footprints, making it feasible for integration into TOF-PET detector prototypes. A 3 × 3 mm2Broadcom SiPM with this readout chain exhibited sub-100 ps single photon time resolution at 10 mW of power consumption, with a relatively minor performance degradation to 120 ± 2 ps FWHM at 5 mW. CTR measurements with 3 × 3 × 20 mm3LYSO and fast LGSO scintillators demonstrated 127 ± 3 ps and 113 ± 2 ps FWHM at optimal power operation and 133 ± 2 ps and 121 ± 3 ps CTR at 5 mW. BGO crystals 3 × 3 × 20 mm3in size show 271 ± 5 ps FWHM CTR (1174 ± 14 ps full-width-at-tenth-maximum (FWTM)) at optimal power dissipation and 289 ± 8 ps (1296 ± 33 ps FWTM) at 5 mW. The compact and low power readout topology that achieves this performance thereby offers a platform to greatly advance PET system CTR and also opportunities to provide high performance TOF-PET at reduced material cost.
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Affiliation(s)
- Joshua W Cates
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Woon-Seng Choong
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
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Park H, Yi M, Lee JS. Silicon photomultiplier signal readout and multiplexing techniques for positron emission tomography: a review. Biomed Eng Lett 2022; 12:263-283. [PMID: 35892029 PMCID: PMC9308856 DOI: 10.1007/s13534-022-00234-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/21/2022] [Accepted: 05/30/2022] [Indexed: 12/03/2022] Open
Abstract
In recent years, silicon photomultiplier (SiPM) is replacing the photomultiplier tube (PMT) in positron emission tomography (PET) systems due to its superior properties, such as fast single-photon timing response, small gap between adjacent photosensitive pixels in the array, and insensitivity to magnetic fields. One of the technical challenges when developing SiPM-based PET systems or other position-sensitive radiation detectors is the large number of output channels coming from the SiPM array. Therefore, various signal multiplexing methods have been proposed to reduce the number of output channels and the load on the subsequent data acquisition (DAQ) system. However, the large PN-junction capacitance and quenching resistance of the SiPM yield undesirable resistance–capacitance delay when multiple SiPMs are combined, which subsequently causes the accumulation of dark counts and signal fluctuation of SiPMs. Therefore, without proper SiPM signal handling and processing, the SiPMs may yield worse timing characteristics than the PMTs. This article reviews the evolution of signal readout and multiplexing methods for the SiPM. In this review, we focus primarily on analog electronics for SiPM signal multiplexing, which allows for the reduction of DAQ channels required for the SiPM-based position-sensitive detectors used in PET and other radiation detector systems. Although the applications of most technologies described in the article are not limited to PET systems, the review highlights efforts to improve the physical performance (e.g. spatial, energy, and timing resolutions) of PET detectors and systems.
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Affiliation(s)
- Haewook Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 South Korea
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
| | - Minseok Yi
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
- Interdisciplinary Program in Bioengineering, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Integrated Major in Innovative Medical Science, Seoul National University College of Engineering, Seoul, 03080 South Korea
| | - Jae Sung Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 South Korea
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
- Interdisciplinary Program in Bioengineering, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Integrated Major in Innovative Medical Science, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Brightonix Imaging Inc, Seoul, 04782 South Korea
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Pagano F, Kratochwil N, Salomoni M, Pizzichemi M, Paganoni M, Auffray E. Advances in heterostructured scintillators: toward a new generation of detectors for TOF-PET. Phys Med Biol 2022; 67. [PMID: 35609611 DOI: 10.1088/1361-6560/ac72ee] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/24/2022] [Indexed: 11/12/2022]
Abstract
Objective.Time-of-flight-positron emission tomography would highly benefit from a coincidence time resolution (CTR) below 100 ps: improvement in image quality and patient workflow, and reduction of delivered dose are among them. This achievement proved to be quite challenging, and many approaches have been proposed and are being investigated for this scope. One of the most recent consists in combining different materials with complementary properties (e.g. high stopping power for 511 keVγ-ray and fast timing) in a so-calledheterostructure,metascintillatorormetapixel. By exploiting a mechanism of energy sharing between the two materials, it is possible to obtain a fraction of fast events which significantly improves the overall time resolution of the system.Approach.In this work, we present the progress on this innovative technology. After a simulation study using the Geant4 toolkit, aimed at understanding the optimal configuration in terms of energy sharing, we assembled four heterostructures with alternating plates of BGO and EJ232 plastic scintillator. We fabricated heterostructures of two different sizes (3 × 3 × 3 mm3and 3 × 3 × 15 mm3), each made up of plates with two different thicknesses of plastic plates. We compared the timing of these pixels with a standard bulk BGO crystal and a structure made of only BGO plates (layeredBGO).Main results.CTR values of 239 ± 12 ps and 197 ± 10 ps FWHM were obtained for the 15 mm long heterostructures with 100µm and 200µm thick EJ232 plates (both with 100µm thick BGO plates), compared to 271 ± 14 ps and 303 ± 15 ps CTR for bulk and layered BGO, respectively.Significance.Significant improvements in timing compared to standard bulk BGO were obtained for all the configurations tested. Moreover, for the long pixels, depth of interaction (DOI) collimated measurements were also performed, allowing to validate a simple model describing light transport inside the heterostructure.
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Affiliation(s)
- Fiammetta Pagano
- CERN, Esplanade de Particules 1, 1211 Meyrin (Geneva), Switzerland.,University of Milano-Bicocca, Piazza dell'Ateneo Nuovo 1, I-20126 Milan, Italy
| | - Nicolaus Kratochwil
- CERN, Esplanade de Particules 1, 1211 Meyrin (Geneva), Switzerland.,University of Vienna, Universitaetsring 1, A-1010 Vienna, Austria
| | - Matteo Salomoni
- CERN, Esplanade de Particules 1, 1211 Meyrin (Geneva), Switzerland
| | - Marco Pizzichemi
- CERN, Esplanade de Particules 1, 1211 Meyrin (Geneva), Switzerland.,University of Milano-Bicocca, Piazza dell'Ateneo Nuovo 1, I-20126 Milan, Italy
| | - Marco Paganoni
- CERN, Esplanade de Particules 1, 1211 Meyrin (Geneva), Switzerland.,University of Milano-Bicocca, Piazza dell'Ateneo Nuovo 1, I-20126 Milan, Italy
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