1
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Mingels C, Chung KJ, Pantel AR, Rominger A, Alberts I, Spencer BA, Nardo L, Pyka T. Total-Body PET/CT: Challenges and Opportunities. Semin Nucl Med 2024:S0001-2998(24)00076-X. [PMID: 39341688 DOI: 10.1053/j.semnuclmed.2024.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Revised: 08/16/2024] [Accepted: 08/19/2024] [Indexed: 10/01/2024]
Abstract
Long-axial field-of-view (LAFOV) systems have changed the field of molecular imaging. Since their introduction, many PET centers have installed these next-generation digital systems to provide more detailed imaging and acquire PET images in a single bed position. Indeed, vertex to thigh imaging for oncological indications can be obtained in most of the population with the currently available LAFOV systems. Moreover, Total Body (TB) PET, a subtype of LAFOV, enables imaging the entire patient-from vertex through the toes-with one bed-position for most of the population. This review aims to identify possible challenges and opportunities for PET-centers working with TB and LAFOV systems. Emphasis is placed on the strength and weaknesses in clinical routine of currently available and upcoming TB and LAFOV PET systems.
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Affiliation(s)
- Clemens Mingels
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Department of Radiology, University of California Davis, Sacramento, CA.
| | - Kevin J Chung
- Department of Radiology, University of California Davis, Sacramento, CA
| | - Austin R Pantel
- Department of Nuclear Medicine Imaging and Therapy, University of Pennsylvania, Philadelphia, PA
| | - Axel Rominger
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Ian Alberts
- Department of Molecular Imaging and Therapy, BC Cancer, Vancouver, British Columbia, Canada; University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Lorenzo Nardo
- Department of Radiology, University of California Davis, Sacramento, CA
| | - Thomas Pyka
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; TUM School of Medicine and Health, Munich, Germany
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2
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Dong Q, Ullah MN, Innes D, Watkins RD, Chang CM, Zou SJ, Groll A, Sacco I, Chinn G, Levin CS. PETcoil: first results from a second-generation RF-penetrable TOF-PET brain insert for simultaneous PET/MRI. Phys Med Biol 2024; 69:185007. [PMID: 39168156 DOI: 10.1088/1361-6560/ad7221] [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: 07/08/2024] [Accepted: 08/21/2024] [Indexed: 08/23/2024]
Abstract
Simultaneous positron emission tomography (PET)/magnetic resonance imaging provides concurrent information about anatomic, functional, and molecular changes in disease. We are developing a second generation MR-compatible RF-penetrable TOF-PET insert. The insert has a smaller scintillation crystal size and ring diameter compared to clinical whole-body PET scanners, resulting in higher spatial resolution and sensitivity. This paper reports the initial system performance of this full-ring PET insert. The global photopeak energy resolution and global coincidence time resolution, 11.74 ± 0.03 % FWHM and 238.1 ± 0.5 ps FWHM, respectively, are preserved as we scaled up the system to a full ring comprising 12, 288 LYSO-SiPM channels (crystal size: 3.2 × 3.2 × 20 mm3). Throughout a ten-hour experiment, the system performance remained stable, exhibiting a less than 1% change in all measured parameters. In a resolution phantom study, the system successfully resolved all 2.8 mm diameter rods, achieving an average VPR of 0.28 ± 0.08 without TOF and 0.24 ± 0.07 with TOF applied. Moreover, the implementation of TOF in the Hoffman phantom study also enhanced image quality. Initial MR compatibility studies of the full PET ring were performed with it unpowered as a milestone to focus on looking for material and geometry-related artifacts. During all MR studies, the MR body coil functioned as both the transmit and receive coil, and no observable artifacts were detected. As expected, using the body coil also as the RF receiver, MR image signal-to-noise ratio exhibited degradation (∼30%), so we are developing a high quality receive-only coil that resides inside the PET ring.
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Affiliation(s)
- Qian Dong
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Muhammad Nasir Ullah
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Derek Innes
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Ronald D Watkins
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Chen-Ming Chang
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Sarah J Zou
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Andrew Groll
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Ilaria Sacco
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Garry Chinn
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
| | - Craig S Levin
- Molecular Imaging Instrumentation Laboratory, Department of Radiology, Stanford University, Stanford, CA, United States of America
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3
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Orehar M, Dolenec R, El Fakhri G, Korpar S, Križan P, Razdevšek G, Marin T, Žontar D, Pestotnik R. Design Optimisation of a Flat-Panel, Limited-Angle TOF-PET Scanner: A Simulation Study. Diagnostics (Basel) 2024; 14:1976. [PMID: 39272760 DOI: 10.3390/diagnostics14171976] [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: 07/22/2024] [Revised: 08/21/2024] [Accepted: 09/02/2024] [Indexed: 09/15/2024] Open
Abstract
In time-of-flight positron emission tomography (TOF-PET), a coincidence time resolution (CTR) below 100 ps reduces the angular coverage requirements and, thus, the geometric constraints of the scanner design. Among other possibilities, this opens the possibility of using flat-panel PET detectors. Such a design would be more cost-accessible and compact and allow for a higher degree of modularity than a conventional ring scanner. However, achieving adequate CTR is a considerable challenge and requires improvements at every level of detection. Based on recent results in the ongoing development of optimised TOF-PET photodetectors and electronics, we expect that within a few years, a CTR of about 75 ps will be be achievable at the system level. In this work, flat-panel scanners with four panels and various design parameters were simulated, assessed and compared to a reference scanner based on the Siemens Biograph Vision using NEMA NU 2-2018 metrics. Point sources were also simulated, and a method for evaluating spatial resolution that is more appropriate for flat-panel geometry is presented. We also studied the effects of crystal readout strategies, comparing single-crystal and module readout levels. The results demonstrate that with a CTR below 100 ps, a flat-panel scanner can achieve image quality comparable to that of a reference clinical scanner, with considerable savings in scintillator material.
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Affiliation(s)
- Matic Orehar
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Rok Dolenec
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
- Jožef Stefan Institute, 1000 Ljubljana, Slovenia
| | | | - Samo Korpar
- Jožef Stefan Institute, 1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor, Slovenia
| | - Peter Križan
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
- Jožef Stefan Institute, 1000 Ljubljana, Slovenia
| | | | - Thibault Marin
- PET Center at Yale School of Medicine, New Haven, CT 06510, USA
| | - Dejan Žontar
- Jožef Stefan Institute, 1000 Ljubljana, Slovenia
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4
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Yoshida E, Yamaya T. PET detectors with depth-of-interaction and time-of-flight capabilities. Radiol Phys Technol 2024; 17:596-609. [PMID: 38888821 DOI: 10.1007/s12194-024-00821-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/09/2024] [Accepted: 06/09/2024] [Indexed: 06/20/2024]
Abstract
In positron emission tomography (PET), measurements of depth-of-interaction (DOI) information and time-of-flight (TOF) information are important. DOI information reduces the parallax error, and TOF information reduces noise by measuring the arrival time difference of the annihilation photons. Historically, these have been studied independently, and there has been less implementation of both DOI and TOF capabilities because previous DOI detectors did not have good TOF resolution. However, recent improvements in PET detector performance have resulted in commercial PET scanners achieving a coincidence resolving time of around 200 ps, which result in an effect even for small objects. This means that TOF information can now be utilized even for a brain PET scanner, which also requires DOI information. Therefore, various methods have been proposed to obtain better DOI and TOF information. In addition, the cost of PET detectors is also an important factor to consider, since several hundred detectors are used per PET scanner. In this paper, we review the latest DOI-TOF detectors including the history of detector development. When put into practical use, these DOI-TOF detectors are expected to contribute to the improvement of imaging performance in brain PET scanners.
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Affiliation(s)
- Eiji Yoshida
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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5
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Li C, Zhang A, Xue Z, Qiu P, Zhang Z, Zhao S, Ding D. Efficient and Ultrafast Oxyorthosilicate Scintillator by Activator Valence State Manipulation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:45197-45206. [PMID: 39150429 DOI: 10.1021/acsami.4c09739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
There is an urgent need for faster, brighter, and more controllable scintillation materials in advanced nuclear medicine, high-energy physical experiments, and dark matter particle detection. Nevertheless, the trade-off between high emission efficiency and fast timing characteristics remains a common challenge in the entire optical field. To address this issue, we develop a composition engineering strategy that involves multisite selective doping. This strategy aims to transform nearly all Ce3+ into fast-emitting Ce4+ while synergistically suppressing the electron traps. Even at very low doping concentrations, the designed Ca2+, Al3+, and Ce3+ tridoped oxyorthosilicate exhibits a scintillation decay (τd) acceleration of 20%, accompanied by a 25% increase in light yield (LY). The ratio of emission efficiency and timing characteristics (LY/τd) can be enhanced by 56%, which realizes the perfect balance of high LY and fast τd. Our work provides a method for designing efficient, ultrafast, and controllable scintillators in multicomponent systems, thus paving the way for high-resolution radiation detection and imaging applications.
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Affiliation(s)
- Chengyi Li
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Aochen Zhang
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhongjun Xue
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
| | - Peng Qiu
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhe Zhang
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
| | - Shuwen Zhao
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
| | - Dongzhou Ding
- Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 585 Heshuo Road, Shanghai 201899, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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6
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Buchsbaum J, Capala J, Obcemea C, Keppel C, Asai M, Chen GH, Christy ME, Fakhri GE, Gueye P, Pogue B, Ruckman L, Tourassi G, Vetter K, Zhao W, Squires A, Saboury B, Wang G, Domurat-Sousa K, Weisenberger A. The United States Department of Energy and National Institutes of Health Collaboration: Medical Care Advances by Discovery in Radiation Detection. Med Phys 2024. [PMID: 39177300 DOI: 10.1002/mp.17333] [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: 06/27/2024] [Accepted: 07/18/2024] [Indexed: 08/24/2024] Open
Abstract
A National Institutes of Health (NIH) and U.S. Department of Energy (DOE) Office of Science virtual workshop on shared general topics was held in July of 2021 and reported on in this publication in January of 2023. Following the inaugural 2021 joint meeting representatives from the DOE Office of Science and NIH met to discuss organizing a second joint workshop that would concentrate on radiation detection to bring together teams from both agencies and their grantee populations to stimulate collaboration and efficiency. To meet this scientific mission within the NIH and DOE radiation detection space, the organizers assembled workshop sessions covering the state-of-the-art in cameras, detectors, and sensors for radiation external and internal (diagnostic and therapeutic) to human, data acquisition and electronics, image reconstruction and processing, and the application of artificial intelligence. NIH and DOE are committed to continuing the process of convening a joint workshop every 12-24 months. This Special Report recaps the findings of this second workshop. Beyond showing only the innovations and areas of success, important gaps in our knowledge were defined and presented. We summarize by defining four areas of greatest opportunity and need that emerged from the unique, dynamic dialogue the in-person workshop provided the attendees.
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Affiliation(s)
| | - Jacek Capala
- National Cancer Institute, Bethesda, Maryland, USA
| | | | - Cynthia Keppel
- Experimental Nuclear Physics, Thomas Jefferson National Accelerator Facility, Newport News, Virginia, USA
| | - Makoto Asai
- Computational Sciences & Technology, Thomas Jefferson National Accelerator Facility, Newport News, Virginia, USA
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - M Eric Christy
- Experimental Nuclear Physics, Thomas Jefferson National Accelerator Facility, Newport News, Virginia, USA
| | - Georges El Fakhri
- Yale PET Center, Department of Radiology & Biomedical Imaging, Department of Bioinformatics & Data Science, Yale University, New Haven, Connecticut, USA
| | - Paul Gueye
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan, USA
| | - Brian Pogue
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Larry Ruckman
- Department of Electronics Systems, SLAC National Accelerator Laboratory, Menlo Park, California, USA
| | - Georgia Tourassi
- National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Kai Vetter
- Department of Nuclear Engineering, University of California, Berkeley, California, USA
| | - Wei Zhao
- Department of Radiology, Stony Brook University, Stony Brook, New York, USA
| | - Allison Squires
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Babak Saboury
- Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Ge Wang
- Biomedical Imaging Center, Rensselaer Polytechnical Institute, Troy, New York, USA
| | - Kepler Domurat-Sousa
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Andrew Weisenberger
- Experimental Nuclear Physics, Thomas Jefferson National Accelerator Facility, Newport News, Virginia, USA
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7
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Yoshida E, Obata F, Yamaya T. Optical crosstalk of protective cover on MPPC array for TOF PET detector. Phys Med Biol 2024; 69:125012. [PMID: 38815615 DOI: 10.1088/1361-6560/ad5268] [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: 03/18/2024] [Accepted: 05/30/2024] [Indexed: 06/01/2024]
Abstract
Objective. Time-of-flight (TOF) is an important factor that directly affects the image quality of PET systems, and various attempts have been made to improve the coincidence resolving time (CRT) of PET detectors. For independent readout detectors, the timing is acquired for each silicon photomultiplier (SiPM), so they are less sensitive to diffused scintillation light, resulting in a better CRT. Further improvement can be expected if the light can be focused on a single SiPM. However, existing SiPM arrays have a thin protective cover on the SiPM and the gap between the SiPMs is filled with either air or the protective cover, so the light must diffuse through the cover. In this work, we investigated optical crosstalk in the protective cover to improve the CRT.Approach. We used 3.1 × 3.1 × 20 mm3fast LGSO crystals and 3 mm square 8 × 8 multi pixel photon counter (MPPC) arrays. Pitch of the MPPCs was 3.2 mm and thickness of the protective cover on them was 150μm. To reduce diffusion of scintillation light in the protective cover, the part of the inactive areas on the MPPC array were optically separated using reflective material. Specifically, 50, 100, 150, and 350μm deep grid-shaped slits were made along the inactive area of the MPPCs and they were filled with BaSO4powder as the reflective material.Main results. Coincidence counts were measured with a pair of TOF detectors, and the CRT was shorter with a deeper slit depth. The CRT before improvement was 235 ps, and using the cover having the 350μm deep slits filled with reflective material lowered the CRT to 211 ps.Significance. Up to 10% of the scintillation light was diffused to other MPPCs by the protective cover, and the CRT was degraded by 10% due to optical crosstalk of the cover. The proposed method promises to improve the CRT of the TOF detector.
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Affiliation(s)
- Eiji Yoshida
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Fujino Obata
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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8
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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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9
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Ye W, Yong Z, Go M, Kowal D, Maddalena F, Tjahjana L, Wang H, Arramel A, Dujardin C, Birowosuto MD, Wong LJ. The Nanoplasmonic Purcell Effect in Ultrafast and High-Light-Yield Perovskite Scintillators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309410. [PMID: 38235521 DOI: 10.1002/adma.202309410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 01/14/2024] [Indexed: 01/19/2024]
Abstract
The development of X-ray scintillators with ultrahigh light yields and ultrafast response times is a long sought-after goal. In this work, a fundamental mechanism that pushes the frontiers of ultrafast X-ray scintillator performance is theoretically predicted and experimentally demonstrated: the use of nanoscale-confined surface plasmon polariton modes to tailor the scintillator response time via the Purcell effect. By incorporating nanoplasmonic materials in scintillator devices, this work predicts over tenfold enhancement in decay rate and 38% reduction in time resolution even with only a simple planar design. The nanoplasmonic Purcell effect is experimentally demonstrated using perovskite scintillators, enhancing the light yield by over 120% to 88 ± 11 ph/keV, and the decay rate by over 60% to 2.0 ± 0.2 ns for the average decay time, and 0.7 ± 0.1 ns for the ultrafast decay component, in good agreement with the predictions of our theoretical framework. Proof-of-concept X-ray imaging experiments are performed using nanoplasmonic scintillators, demonstrating 182% enhancement in the modulation transfer function at four line pairs per millimeter spatial frequency. This work highlights the enormous potential of nanoplasmonics in optimizing ultrafast scintillator devices for applications including time-of-flight X-ray imaging and photon-counting computed tomography.
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Affiliation(s)
- Wenzheng Ye
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Zhihua Yong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Michael Go
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Dominik Kowal
- Łukasiewicz Research Network-PORT Polish Center for Technology Development, Stabłowicka 147, 54-066, Wrocław, Poland
| | - Francesco Maddalena
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Liliana Tjahjana
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Hong Wang
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
| | - Arramel Arramel
- Nano Center Indonesia, Jalan Raya PUSPIPTEK, South Tangerang, Banten, 15314, Indonesia
| | - Christophe Dujardin
- Universite Claude Bernard Lyon 1, Institut Lumière Matière, UMR 5306 CNRS, Villeurbanne, F-69622, France
- Institut Universitaire de France, 1 Rue Descartes, Paris, Île-de-France, 75005, Paris, France
| | - Muhammad Danang Birowosuto
- Łukasiewicz Research Network-PORT Polish Center for Technology Development, Stabłowicka 147, 54-066, Wrocław, Poland
| | - Liang Jie Wong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- CINTRA (CNRS-International-NTU-THALES Research Alliance), IRL 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore, 637553, Singapore
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10
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Onishi Y, Hashimoto F, Ote K, Ota R. Whole Reconstruction-Free System Design for Direct Positron Emission Imaging From Image Generation to Attenuation Correction. IEEE TRANSACTIONS ON MEDICAL IMAGING 2024; 43:1654-1663. [PMID: 38109238 DOI: 10.1109/tmi.2023.3344095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Direct positron emission imaging (dPEI), which does not require a mathematical reconstruction step, is a next-generation molecular imaging modality. To maximize the practical applicability of the dPEI system to clinical practice, we introduce a novel reconstruction-free image-formation method called direct μCompton imaging, which directly localizes the interaction position of Compton scattering from the annihilation photons in a three-dimensional space by utilizing the same compact geometry as that for dPEI, involving ultrafast time-of-flight radiation detectors. This unique imaging method not only provides the anatomical information about an object but can also be applied to attenuation correction of dPEI images. Evaluations through Monte Carlo simulation showed that functional and anatomical hybrid images can be acquired using this multimodal imaging system. By fusing the images, it is possible to simultaneously access various object data, which ensures the synergistic effect of the two imaging methodologies. In addition, attenuation correction improves the quantification of dPEI images. The realization of the whole reconstruction-free imaging system from image generation to quantitative correction provides a new perspective in molecular imaging.
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11
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Hashimoto F, Onishi Y, Ote K, Tashima H, Reader AJ, Yamaya T. Deep learning-based PET image denoising and reconstruction: a review. Radiol Phys Technol 2024; 17:24-46. [PMID: 38319563 PMCID: PMC10902118 DOI: 10.1007/s12194-024-00780-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 02/07/2024]
Abstract
This review focuses on positron emission tomography (PET) imaging algorithms and traces the evolution of PET image reconstruction methods. First, we provide an overview of conventional PET image reconstruction methods from filtered backprojection through to recent iterative PET image reconstruction algorithms, and then review deep learning methods for PET data up to the latest innovations within three main categories. The first category involves post-processing methods for PET image denoising. The second category comprises direct image reconstruction methods that learn mappings from sinograms to the reconstructed images in an end-to-end manner. The third category comprises iterative reconstruction methods that combine conventional iterative image reconstruction with neural-network enhancement. We discuss future perspectives on PET imaging and deep learning technology.
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Affiliation(s)
- Fumio Hashimoto
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan.
- Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-Ku, Chiba, 263-8522, Japan.
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan.
| | - Yuya Onishi
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan
| | - Kibo Ote
- Central Research Laboratory, Hamamatsu Photonics K. K, 5000 Hirakuchi, Hamana-Ku, Hamamatsu, 434-8601, Japan
| | - Hideaki Tashima
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan
| | - Andrew J Reader
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, SE1 7EH, UK
| | - Taiga Yamaya
- Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-Ku, Chiba, 263-8522, Japan
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba, 263-8555, Japan
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12
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Cates JW, Choong WS, Brubaker E. Scintillation and cherenkov photon counting detectors with analog silicon photomultipliers for TOF-PET. Phys Med Biol 2024; 69:045025. [PMID: 38252971 PMCID: PMC10861944 DOI: 10.1088/1361-6560/ad2125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/05/2024] [Accepted: 01/22/2024] [Indexed: 01/24/2024]
Abstract
Objective.Standard signal processing approaches for scintillation detectors in positron emission tomography (PET) derive accurate estimates for 511 keV photon time of interaction and energy imparted to the detection media from aggregate characteristics of electronic pulse shapes. The ultimate realization of a scintillation detector for PET is one that provides a unique timestamp and position for each detected scintillation photon. Detectors with these capabilities enable advanced concepts for three-dimensional (3D) position and time of interaction estimation with methods that exploit the spatiotemporal arrival time kinetics of individual scintillation photons.Approach.In this work, we show that taking into consideration the temporal photon emission density of a scintillator, the channel density of an analog silicon photomultiplier (SiPM) array, and employing fast electronic readout with digital signal processing, a detector that counts and timestamps scintillation photons can be realized. To demonstrate this approach, a prototype detector was constructed, comprising multichannel electronic readout for a bismuth germanate (BGO) scintillator coupled to an SiPM array.Main Results.In proof-of-concept measurements with this detector, we were able to count and provide unique timestamps for 66% of all optical photons, where the remaining 34% (two-or-more-photon pulses) are also independently counted, but each photon bunch shares a common timestamp. We show this detector concept can implement 3D positioning of 511 keV photon interactions and thereby enable corrections for time of interaction estimators. The detector achieved 17.6% energy resolution at 511 keV and 237 ± 10 ps full-width-at-half-maximum coincidence time resolution (CTR) (fast spectral component) versus a reference detector. We outline the methodology, readout, and approach for achieving this detector capability in first-ever, proof-of-concept measurements for scintillation photon counting detector with analog silicon photomultipliers.Significance.The presented detector concept is a promising design for large area, high sensitivity TOF-PET detector modules that can implement advanced event positioning and time of interaction estimators, which could push state-of-the-art performance.
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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
| | - Erik Brubaker
- Sandia National Laboratories, Livermore, CA, United States of America
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13
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Jeong D, Tao L, Song XR, Adams Z, Zhang X, Wang J, Levin CS. Simulation of ionization charge carrier cascade time and density for a new radiation detection method based on modulation of optical properties. Med Phys 2024; 51:1383-1395. [PMID: 38064645 PMCID: PMC10922253 DOI: 10.1002/mp.16855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 02/10/2024] Open
Abstract
BACKGROUND In time-of-flight PET, image quality and accuracy can be enhanced by improving the annihilation photon pair coincidence time resolution, which is the variation in the arrival time difference between the two annihilation photons emitted from each positron decay in the patient. Recent studies suggest direct detection of ionization tracks and their resulting modulation of optical properties, instead of scintillation, can improve the CTR significantly, potentially down to less than 10 ps CTR. However, the arrival times of the 511 keV photons are not predictable, leading to challenges in the spatiotemporal localization characterization of the induced charge carriers in the detector crystal. PURPOSE To establish an optimized experimental setup for measuring ionization induced modulation of optical properties, it is critical to develop a versatile simulation algorithm that can handle multiple detector material properties and time-resolved charge carrier dynamics. METHODS We expanded our previous algorithm and simulated ionization tracks, cascade time and induced charge carrier density over time in different materials. For designing a proof-of-concept experiment, we simulated ultrafast electrons and free-electron x-ray photons for timing characterization along with alpha and beta particles for higher spatial localization. RESULTS With 3 MeV ultrafast electrons, by reducing detector crystal thickness, we can effectively reduce the ionization cascade time to 0.79 ps and deposited energy to 198.5 keV, which is on the order of the desired 511 keV energy. Alpha source simulations produced a cascade time of 2.45 ps and charge carrier density of 6.39 × 1020 cm-3 . Compared to the previous results obtained from 511 keV photon-induced ionization track simulations, the cascade time displayed similar characteristics, while the charge density was found to be higher. These findings suggest that alpha sources have the potential to generate a stronger ionization-induced signal using the modulation of optical properties as the detection mechanism. CONCLUSIONS This work provides a guideline to understand, design and optimize an experimental platform that is highly sensitive and temporally precise enough to detect single 511 keV photon interactions with a goal to advance CTR for ToF-PET.
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Affiliation(s)
- Diana Jeong
- Department of Radiology, Stanford University, Stanford, USA
| | - Li Tao
- Department of Radiology, Stanford University, Stanford, USA
- Department of Electrical Engineering, Stanford University, Stanford, USA
| | - Xin Ran Song
- Department of Radiology, Stanford University, Stanford, USA
| | - Zander Adams
- Department of Radiology, Stanford University, Stanford, USA
| | - Xin Zhang
- Department of Radiology, Stanford University, Stanford, USA
| | - Jinghui Wang
- Department of Radiation Oncology, Stanford University, Stanford, USA
| | - Craig S Levin
- Department of Radiology, Stanford University, Stanford, USA
- Department of Electrical Engineering, Stanford University, Stanford, USA
- Department of Physics, Stanford University, Stanford, USA
- Department of Bioengineering, Stanford University, Stanford, USA
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14
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Sanaat A, Amini M, Arabi H, Zaidi H. The quest for multifunctional and dedicated PET instrumentation with irregular geometries. Ann Nucl Med 2024; 38:31-70. [PMID: 37952197 PMCID: PMC10766666 DOI: 10.1007/s12149-023-01881-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/09/2023] [Indexed: 11/14/2023]
Abstract
We focus on reviewing state-of-the-art developments of dedicated PET scanners with irregular geometries and the potential of different aspects of multifunctional PET imaging. First, we discuss advances in non-conventional PET detector geometries. Then, we present innovative designs of organ-specific dedicated PET scanners for breast, brain, prostate, and cardiac imaging. We will also review challenges and possible artifacts by image reconstruction algorithms for PET scanners with irregular geometries, such as non-cylindrical and partial angular coverage geometries and how they can be addressed. Then, we attempt to address some open issues about cost/benefits analysis of dedicated PET scanners, how far are the theoretical conceptual designs from the market/clinic, and strategies to reduce fabrication cost without compromising performance.
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Affiliation(s)
- Amirhossein Sanaat
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - Mehdi Amini
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - Hossein Arabi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva, Switzerland.
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, 9700 RB, Groningen, The Netherlands.
- Department of Nuclear Medicine, University of Southern Denmark, 500, Odense, Denmark.
- University Research and Innovation Center, Óbuda University, Budapest, Hungary.
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15
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Lee JS, Lee MS. Advancements in Positron Emission Tomography Detectors: From Silicon Photomultiplier Technology to Artificial Intelligence Applications. PET Clin 2024; 19:1-24. [PMID: 37802675 DOI: 10.1016/j.cpet.2023.06.003] [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] [Indexed: 10/08/2023]
Abstract
This review article focuses on PET detector technology, which is the most crucial factor in determining PET image quality. The article highlights the desired properties of PET detectors, including high detection efficiency, spatial resolution, energy resolution, and timing resolution. Recent advancements in PET detectors to improve these properties are also discussed, including the use of silicon photomultiplier technology, advancements in depth-of-interaction and time-of-flight PET detectors, and the use of artificial intelligence for detector development. The article provides an overview of PET detector technology and its recent advancements, which can significantly enhance PET image quality.
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Affiliation(s)
- Jae Sung Lee
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 03080, South Korea; Brightonix Imaging Inc., Seoul 04782, South Korea
| | - Min Sun Lee
- Environmental Radioactivity Assessment Team, Nuclear Emergency & Environmental Protection Division, Korea Atomic Energy Research Institute, Daejeon 34057, South Korea.
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16
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Nuyts J, Defrise M, Morel C, Lecoq P. The SNR of time-of-flight positron emission tomography data for joint reconstruction of the activity and attenuation images. Phys Med Biol 2023; 69:10.1088/1361-6560/ad078c. [PMID: 37890469 PMCID: PMC10811362 DOI: 10.1088/1361-6560/ad078c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/27/2023] [Indexed: 10/29/2023]
Abstract
Objective.Measurement of the time-of-flight (TOF) difference of each coincident pair of photons increases the effective sensitivity of positron emission tomography (PET). Many authors have analyzed the benefit of TOF for quantification and hot spot detection in the reconstructed activity images. However, TOF not only improves the effective sensitivity, it also enables the joint reconstruction of the tracer concentration and attenuation images. This can be used to correct for errors in CT- or MR-derived attenuation maps, or to apply attenuation correction without the help of a second modality. This paper presents an analysis of the effect of TOF on the variance of the jointly reconstructed attenuation and (attenuation corrected) tracer concentration images.Approach.The analysis is performed for PET systems that have a distribution of possibly non-Gaussian TOF-kernels, and includes the conventional Gaussian TOF-kernel as a special case. Non-Gaussian TOF-kernels are often observed in novel detector designs, which make use of two (or more) different mechanisms to convert the incoming 511 keV photon to optical photons. The analytical result is validated with a simple 2D simulation.Main results.We show that if two different TOF-kernels are equivalent for image reconstruction with known attenuation, then they are also equivalent for joint reconstruction of the activity and the attenuation images. The variance increase in the activity, caused by also jointly reconstructing the attenuation image, vanishes when the TOF-resolution approaches perfection.Significance.These results are of interest for PET detector development and for the development of stand-alone PET systems.
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Affiliation(s)
- Johan Nuyts
- KU Leuven, University of Leuven, Department of Imaging and Pathology, Nuclear Medicine & Molecular imaging; Medical Imaging Research Center (MIRC), B-3000, Leuven, Belgium
| | - Michel Defrise
- Department of Nuclear Medicine, Vrije Universiteit Brussel, B-1090, Brussels, Belgium
| | | | - Paul Lecoq
- Polytechnic University of Valencia, Spain
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17
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Iwao Y, Akamatsu G, Tashima H, Takahashi M, Yamaya T. Pre-acquired CT-based attenuation correction with automated headrest removal for a brain-dedicated PET system. Radiol Phys Technol 2023; 16:552-559. [PMID: 37819445 DOI: 10.1007/s12194-023-00744-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 10/13/2023]
Abstract
Attenuation correction (AC) is essential for quantitative positron emission tomography (PET) images. Attenuation coefficient maps (μ-maps) are usually generated from computed tomography (CT) images when PET-CT combined systems are used. If CT has been performed prior to PET imaging, pre-acquired CT can be used for brain PET AC, because the human head is almost rigid. This pre-acquired CT-based AC approach is suitable for stand-alone brain-dedicated PET, such as VRAIN (ATOX Co. Ltd., Tokyo, Japan). However, the headrest of PET is different from the headrest in pre-acquired CT images, which may degrade the PET image quality. In this study, we prepared three different types of μ-maps: (1) based on the pre-acquired CT, where namely the headrest is different from the PET system (μ-map-diffHr); (2) manually removing the headrest from the pre-acquired CT (μ-map-noHr); and (3) artificially replacing the headrest region with the headrest of the PET system (μ-map-sameHr). Phantom images by VRAIN using each μ-map were investigated for uniformity, noise, and quantitative accuracy. Consequently, only the uniformity of the images using μ-map-diffHr was out of the acceptance criteria. We then proposed an automated method for removing the headrest from pre-acquired CT images. In comparisons of standardized uptake values in nine major brain regions from the 18F-fluoro-2-deoxy-D-glucose-PET of 10 healthy volunteers, no significant differences were found between the μ-map-noHr and the μ-map-sameHr. In conclusion, pre-acquired CT-based AC with automated headrest removal is useful for brain-dedicated PET such as VRAIN.
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Affiliation(s)
- Yuma Iwao
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-Ku, Chiba, 263-8555, Japan.
| | - Go Akamatsu
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-Ku, Chiba, 263-8555, Japan.
| | - Hideaki Tashima
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-Ku, Chiba, 263-8555, Japan
| | - Miwako Takahashi
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-Ku, Chiba, 263-8555, Japan
| | - Taiga Yamaya
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-Ku, Chiba, 263-8555, Japan.
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18
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Erroi A, Mecca S, Zaffalon ML, Frank I, Carulli F, Cemmi A, Di Sarcina I, Debellis D, Rossi F, Cova F, Pauwels K, Mauri M, Perego J, Pinchetti V, Comotti A, Meinardi F, Vedda A, Auffray E, Beverina L, Brovelli S. Ultrafast and Radiation-Hard Lead Halide Perovskite Nanocomposite Scintillators. ACS ENERGY LETTERS 2023; 8:3883-3894. [PMID: 37705701 PMCID: PMC10497040 DOI: 10.1021/acsenergylett.3c01396] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/03/2023] [Indexed: 09/15/2023]
Abstract
The use of scintillators for the detection of ionizing radiation is a critical aspect in many fields, including medicine, nuclear monitoring, and homeland security. Recently, lead halide perovskite nanocrystals (LHP-NCs) have emerged as promising scintillator materials. However, the difficulty of affordably upscaling synthesis to the multigram level and embedding NCs in optical-grade nanocomposites without compromising their optical properties still limits their widespread use. In addition, fundamental aspects of the scintillation mechanisms are not fully understood, leaving the scientific community without suitable fabrication protocols and rational guidelines for the full exploitation of their potential. In this work, we realize large polyacrylate nanocomposite scintillators based on CsPbBr3 NCs, which are synthesized via a novel room temperature, low waste turbo-emulsification approach, followed by their in situ transformation during the mass polymerization process. The interaction between NCs and polymer chains strengthens the scintillator structure, homogenizes the particle size distribution and passivates NC defects, resulting in nanocomposite prototypes with luminescence efficiency >90%, exceptional radiation hardness, 4800 ph/MeV scintillation yield even at low NC loading, and ultrafast response time, with over 30% of scintillation occurring in the first 80 ps, promising for fast-time applications in precision medicine and high-energy physics. Ultrafast radioluminescence and optical spectroscopy experiments using pulsed synchrotron light further disambiguate the origin of the scintillation kinetics as the result of charged-exciton and multiexciton recombination formed under ionizing excitation. This highlights the role of nonradiative Auger decay, whose potential impact on fast timing applications we anticipate via a kinetic model.
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Affiliation(s)
- Andrea Erroi
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Sara Mecca
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Matteo L. Zaffalon
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Isabel Frank
- CERN, Esplanade des Particules 1, 1211 Meyrin, Switzerland
- LMU
Munich, Geschwister-Scholl-Platz
1, 80539 Munich, Germany
| | - Francesco Carulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Alessia Cemmi
- ENEA
Fusion and Technology for Nuclear Safety and Security Department,
Casaccia R.C., Via Anguillarese 301, 00123 Rome, Italy
| | - Ilaria Di Sarcina
- ENEA
Fusion and Technology for Nuclear Safety and Security Department,
Casaccia R.C., Via Anguillarese 301, 00123 Rome, Italy
| | - Doriana Debellis
- Electron
Microscopy Facility, Istituto Italiano di
Tecnologia, 16163 Genova, Italy
| | - Francesca Rossi
- IMEM-CNR
Institute, Parco Area
delle Scienze 37/A, 43124 Parma, Italy
| | - Francesca Cova
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Kristof Pauwels
- ESRF
- The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Michele Mauri
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Jacopo Perego
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Valerio Pinchetti
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Angiolina Comotti
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Francesco Meinardi
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Anna Vedda
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | | | - Luca Beverina
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
| | - Sergio Brovelli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi Milano - Bicocca, via R. Cozzi 55, 20126 Milan, Italy
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19
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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: 1] [Impact Index Per Article: 1.0] [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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Cuny T, Fargette C, Taïeb D. Imaging of multiple endocrine neoplasia type 1 patients in the era of somatostatin receptor positron emission tomography–computed tomography: “no place to hide for neuroendocrine tumours”. Eur J Endocrinol 2023; 188:C9-C10. [PMID: 37220756 DOI: 10.1093/ejendo/lvad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 04/22/2023] [Accepted: 05/10/2023] [Indexed: 05/13/2023]
Affiliation(s)
- Thomas Cuny
- APHM, Marseille Medical Genetics, Inserm U1251, Conception Hospital, Endocrinology Department, Aix Marseille University , Marseille , France
| | - Christelle Fargette
- Department of Nuclear Medicine, La Timone University Hospital, European Center for Research in Medical Imaging, Aix-Marseille University , Marseille , France
| | - David Taïeb
- Department of Nuclear Medicine, La Timone University Hospital, European Center for Research in Medical Imaging, Aix-Marseille University , Marseille , France
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21
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Llosá G, Rafecas M. Hybrid PET/Compton-camera imaging: an imager for the next generation. EUROPEAN PHYSICAL JOURNAL PLUS 2023; 138:214. [PMID: 36911362 PMCID: PMC9990967 DOI: 10.1140/epjp/s13360-023-03805-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 02/11/2023] [Indexed: 06/18/2023]
Abstract
Compton cameras can offer advantages over gamma cameras for some applications, since they are well suited for multitracer imaging and for imaging high-energy radiotracers, such as those employed in radionuclide therapy. While in conventional clinical settings state-of-the-art Compton cameras cannot compete with well-established methods such as PET and SPECT, there are specific scenarios in which they can constitute an advantageous alternative. The combination of PET and Compton imaging can benefit from the improved resolution and sensitivity of current PET technology and, at the same time, overcome PET limitations in the use of multiple radiotracers. Such a system can provide simultaneous assessment of different radiotracers under identical conditions and reduce errors associated with physical factors that can change between acquisitions. Advances are being made both in instrumentation developments combining PET and Compton cameras for multimodal or three-gamma imaging systems, and in image reconstruction, addressing the challenges imposed by the combination of the two modalities or the new techniques. This review article summarizes the advances made in Compton cameras for medical imaging and their combination with PET.
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Affiliation(s)
- Gabriela Llosá
- Instituto de Física Corpuscular (IFIC), CSIC-UV, Catedrático Beltrán, 2., 46980 Paterna, Valencia, Spain
| | - Magdalena Rafecas
- Institute of Medical Engineering (IMT), Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
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22
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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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23
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Sundberg C, Persson M, Wikner JJ, Danielsson M. Timing resolution in double-sided silicon photon-counting computed tomography detectors. J Med Imaging (Bellingham) 2023; 10:023502. [PMID: 36969328 PMCID: PMC10035543 DOI: 10.1117/1.jmi.10.2.023502] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 02/22/2023] [Indexed: 03/25/2023] Open
Abstract
Purpose Our purpose is to investigate the timing resolution in edge-on silicon strip detectors for photon-counting spectral computed tomography. Today, the timing for detection of individual x-rays is not measured, but in the future, timing information can be valuable to accurately reconstruct the interactions caused by each primary photon. Approach We assume a pixel size of 12 × 500 μ m 2 and a detector with double-sided readout with low-noise CMOS electronics for pulse processing for every pixel on each side. Due to the electrode width in relation to the wafer thickness, the induced current signals are largely dominated by charge movement close to the collecting electrodes. By employing double-sided readout electrodes, at least two signals are generated for each interaction. By comparing the timing of the induced current pulses, the time of the interaction can be determined and used to identify interactions that originate from the same incident photon. Using a Monte Carlo simulation of photon interactions in combination with a charge transport model, we evaluate the performance of estimating the time of the interaction for different interaction positions. Results Our simulations indicate that a time resolution of 1 ns can be achieved with a noise level of 0.5 keV. In a detector with no electronic noise, the corresponding time resolution is ∼ 0.1 ns . Conclusions Time resolution in edge-on silicon strip CT detectors can potentially be used to increase the signal-to-noise-ratio and energy resolution by helping in identifying Compton scattered photons in the detector.
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Affiliation(s)
- Christel Sundberg
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden
- Prismatic Sensors, Part of GE Healthcare, AlbaNova University Center, Stockholm, Sweden
| | - Mats Persson
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden
- MedTechLabs, BioClinicum, Karolinska University Hospital, Solna, Sweden
| | - J. Jacob Wikner
- Prismatic Sensors, Part of GE Healthcare, AlbaNova University Center, Stockholm, Sweden
- Linköping University, Department of Electrical Engineering, Linköping, Sweden
| | - Mats Danielsson
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden
- MedTechLabs, BioClinicum, Karolinska University Hospital, Solna, Sweden
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24
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Lyu Q, Neph R, Sheng K. Tomographic detection of photon pairs produced from high-energy X-rays for the monitoring of radiotherapy dosing. Nat Biomed Eng 2023; 7:323-334. [PMID: 36280738 PMCID: PMC10038801 DOI: 10.1038/s41551-022-00953-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 09/14/2022] [Indexed: 01/07/2023]
Abstract
Measuring the radiation dose reaching a patient's body is difficult. Here we report a technique for the tomographic reconstruction of the location of photon pairs originating from the annihilation of positron-electron pairs produced by high-energy X-rays travelling through tissue. We used Monte Carlo simulations on pre-recorded data from tissue-mimicking phantoms and from a patient with a brain tumour to show the feasibility of this imaging modality, which we named 'pair-production tomography', for the monitoring of radiotherapy dosing. We simulated three image-reconstruction methods, one applicable to a pencil X-ray beam scanning through a region of interest, and two applicable to the excitation of tissue volumes via broad beams (with temporal resolution sufficient to identify coincident photon pairs via filtered back projection, or with higher temporal resolution sufficient for the estimation of a photon's time-of-flight). In addition to the monitoring of radiotherapy dosing, we show that image contrast resulting from pair-production tomography is highly proportional to the material's atomic number. The technique may thus also allow for element mapping and for soft-tissue differentiation.
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Affiliation(s)
- Qihui Lyu
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA
| | - Ryan Neph
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA
| | - Ke Sheng
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA.
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25
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Zatcepin A, Ziegler SI. Detectors in positron emission tomography. Z Med Phys 2023; 33:4-12. [PMID: 36208967 PMCID: PMC10082375 DOI: 10.1016/j.zemedi.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/25/2022] [Indexed: 11/05/2022]
Abstract
Positron emission tomography is a highly sensitive molecular imaging modality, based on the coincident detection of annihilation photons after positron decay. The most used detector is based on dense, fast, and luminous scintillators read out by light sensors. This review covers the various detector concepts for clinical and preclinical systems.
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Affiliation(s)
- Artem Zatcepin
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Sibylle I Ziegler
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany.
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26
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Kiyokawa M, Kang HG, Yamaya T. Tracking the same fast-LGSO crystals by changing surface treatments for better coincidence timing resolution in PET. Biomed Phys Eng Express 2023; 9. [PMID: 36689772 DOI: 10.1088/2057-1976/acb552] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/23/2023] [Indexed: 01/24/2023]
Abstract
Achieving fast coincidence timing resolution (CTR) is an important issue in clinical time-of-flight positron emission tomography (TOF-PET) to improve the reconstructed image quality. One of the major factors affecting the CTR is the crystal surface treatment, which is often parameterized as surface roughness. However, previous studies on the crystal surface treatment optimization had two limitations of crystal-by-crystal variation and worse CTR over 200 ps. Here, we report the effects of the crystal surface treatment on the performance of a 20 mm long fast-LGSO crystal based TOF detector by tracking the same crystals in the sub-180 ps CTR regime. The light collection efficiency (LCE), energy resolution (ER) and CTR of the TOF detector were evaluated with six different crystal surface treatments of chemically polished (C.P), C.P half side roughened (1/2S) treatment, and then the C.P one side roughened (1S) treatment, mechanically polished (M.P) treatment, M.P 1/2S treatment, and M.P 1S treatment. The four lateral surfaces of each crystal were wrapped by using enhanced specular reflector film while the top surface was covered by using Teflon tape. The bottom surface of the crystal was optically coupled to a silicon photomultiplier. The timing and energy signals were extracted by using a custom-made high-frequency readout circuit, and then digitized by using a waveform digitizer. All the experimental conditions were same except the crystal surface treatment. Among the six different crystal surface treatments, the M.P 1S would be the optimal crystal surface treatment which balanced enhancements in the CTR (165 ± 3 ps) and ER (10.5 ± 0.5%). Unlike the M.P 1S, the C.P 1S did not enhance the CTR and ER. Hence, the C.P without roughening would be the second-best optimal crystal surface treatment which balanced the CTR (169 ± 3 ps) and ER (10.5 ± 0.5%).
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Affiliation(s)
- Miho Kiyokawa
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba, Japan.,Department of Medical Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba, 263-8522, Japan
| | - Han Gyu Kang
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba, Japan.,Center for Frontier Medical Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba, 263-8522, Japan
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27
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Parodi K, Yamaya T, Moskal P. Experience and new prospects of PET imaging for ion beam therapy monitoring. Z Med Phys 2023; 33:22-34. [PMID: 36446691 PMCID: PMC10068545 DOI: 10.1016/j.zemedi.2022.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 10/11/2022] [Accepted: 11/02/2022] [Indexed: 11/27/2022]
Abstract
Pioneering investigations on the usage of positron-emission-tomography (PET) for the monitoring of ion beam therapy with light (protons, helium) and heavier (stable and radioactive neon, carbon and oxygen) ions started shortly after the first realization of planar and tomographic imaging systems, which were able to visualize the annihilation of positrons resulting from irradiation induced or implanted positron emitting nuclei. And while the first clinical experience was challenged by the utilization of instrumentation directly adapted from nuclear medicine applications, new detectors optimized for this unconventional application of PET imaging are currently entering the phase of (pre)clinical testing for more reliable monitoring of treatment delivery during irradiation. Moreover, recent advances in detector technologies and beam production open several new exciting opportunities which will not only improve the performance of PET imaging under the challenging conditions of in-beam applications in ion beam therapy, but will also likely expand its field of application. In particular, the combination of PET and Compton imaging can enable the most efficient utilization of all possible radiative emissions for both stable and radioactive ion beams, while positronium lifetime imaging may enable probing new features of the underlying tumour and normal tissue environment. Thereby, PET imaging will not only provide means for volumetric reconstruction of the delivered treatment and in-vivo verification of the beam range, but can also shed new insights for biological optimization of the treatment or treatment response assessment.
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Affiliation(s)
- Katia Parodi
- Ludwig-Maximilians-Universität München, Lehrstuhl für Experimental Physik - Medizinische Physik, Garching b. München, Germany.
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Pawel Moskal
- M. Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland; Center for Theranostics, Jagiellonian University, Krakow, Poland
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28
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Konstantinou G, Latella R, Moliner L, Zhang L, Benlloch JM, Gonzalez AJ, Lecoq P. A proof-of-concept of cross-luminescent metascintillators: testing results on a BGO:BaF 2metapixel. Phys Med Biol 2023; 68. [PMID: 36595320 DOI: 10.1088/1361-6560/acac5f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
Objective: Time-of-flight positron emission tomography (PET) is the next frontier in improving the effective sensitivity. To achieve superior timing for time-of-flight PET, combined with high detection efficiency and cost-effectiveness, we have studied the applicability of BaF2 in metascintillators driven by the timing of cross-luminescence photon production.Approach: Based on previous simulation studies of energy sharing and analytic multi-exponential scintillation pulse, as well as sensitivity characteristics, we have experimentally tested a pixel of 3 × 3 × 15 mm3 based on 300μm BGO and 300μm BaF2 layers. To harness the deep ultraviolet cross-luminescent light component, which carries improved timing, we use the FBK VUV SiPM. Metascintillator energy sharing is addressed through a double integration approach.Main results: We reach an energy resolution of 22%, comparable to an 18% resolution of simple BGO pixels using the same readout, through the optimized use of the integrals of the metascintillator pulse in energy sharing calculation. We measure the energy sharing extent of each pulse with a resolution of 25% and demonstrate that experimental and simulation results agree well. Based on the energy sharing, a timewalk correction is applied, exhibiting significant improvements for both the coincidence time resolution (CTR) and the shape of the timing histogram. We reach 242 ps CTR for the entire photopeak, while for a subset of 13% of the most shared events, the CTR value improves to 108 ps, comparable to the 3 × 3 × 5 mm3 LYSO:Ce:Ca reference crystal.Significance: While we are considering different ways to improve further these results, this proof-of-concept demonstrates the applicability of cross-luminescence for metascintillator designs through the application of VUV compatible SiPM coupling, and easily implementable digital algorithms. This is the first test of BaF2-based metascintillators of sufficient stoppng power to be included in a PET scanner, demonstrating the industrial applicability of such cross-luminescent metascintillators.
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Affiliation(s)
- G Konstantinou
- Multiwave Metacrystal S.A., 34 Route de la Galaise, 1228, Geneva, Switzerland.,Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - R Latella
- Multiwave Metacrystal S.A., 34 Route de la Galaise, 1228, Geneva, Switzerland.,Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - L Moliner
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - L Zhang
- Multiwave Metacrystal S.A., 34 Route de la Galaise, 1228, Geneva, Switzerland
| | - J M Benlloch
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - A J Gonzalez
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
| | - P Lecoq
- Multiwave Metacrystal S.A., 34 Route de la Galaise, 1228, Geneva, Switzerland.,Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
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29
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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: 8] [Impact Index Per Article: 4.0] [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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30
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Sarrut D, Arbor N, Baudier T, Borys D, Etxebeste A, Fuchs H, Gajewski J, Grevillot L, Jan S, Kagadis GC, Kang HG, Kirov A, Kochebina O, Krzemien W, Lomax A, Papadimitroulas P, Pommranz C, Roncali E, Rucinski A, Winterhalter C, Maigne L. The OpenGATE ecosystem for Monte Carlo simulation in medical physics. Phys Med Biol 2022; 67:10.1088/1361-6560/ac8c83. [PMID: 36001985 PMCID: PMC11149651 DOI: 10.1088/1361-6560/ac8c83] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/24/2022] [Indexed: 11/12/2022]
Abstract
This paper reviews the ecosystem of GATE, an open-source Monte Carlo toolkit for medical physics. Based on the shoulders of Geant4, the principal modules (geometry, physics, scorers) are described with brief descriptions of some key concepts (Volume, Actors, Digitizer). The main source code repositories are detailed together with the automated compilation and tests processes (Continuous Integration). We then described how the OpenGATE collaboration managed the collaborative development of about one hundred developers during almost 20 years. The impact of GATE on medical physics and cancer research is then summarized, and examples of a few key applications are given. Finally, future development perspectives are indicated.
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Affiliation(s)
- David Sarrut
- Université de Lyon; CREATIS; CNRS UMR5220; Inserm U1294; INSA-Lyon; Université Lyon 1, Léon Bérard cancer center, Lyon, France
| | - Nicolas Arbor
- Université de Strasbourg, IPHC, CNRS, UMR7178, F-67037 Strasbourg, France
| | - Thomas Baudier
- Université de Lyon; CREATIS; CNRS UMR5220; Inserm U1294; INSA-Lyon; Université Lyon 1, Léon Bérard cancer center, Lyon, France
| | - Damian Borys
- Department of Systems Biology and Engineering, Silesian University of Technology, Gliwice, Poland
| | - Ane Etxebeste
- Université de Lyon; CREATIS; CNRS UMR5220; Inserm U1294; INSA-Lyon; Université Lyon 1, Léon Bérard cancer center, Lyon, France
| | - Hermann Fuchs
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Medical University of Vienna, Department of Radiation Oncology, Vienna, Vienna, Währinger Gürtel 18-20, A-1090 Wien, Austria
| | - Jan Gajewski
- Institute of Nuclear Physics Polish Academy of Sciences, Krakow, Poland
| | | | - Sébastien Jan
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale (BioMaps), F-91401 Orsay, France
| | - George C Kagadis
- 3DMI Research Group, Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece
| | - Han Gyu Kang
- National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Assen Kirov
- Memorial Sloan Kettering Cancer, New York, NY 10021, United States of America
| | - Olga Kochebina
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale (BioMaps), F-91401 Orsay, France
| | - Wojciech Krzemien
- High Energy Physics Division, National Centre for Nuclear Research, Otwock-Świerk, Poland
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Lojasiewicza 11, 30-348 Krakow, Poland
- Centre for Theranostics, Jagiellonian University, Kopernika 40 St, 31 501 Krakow, Poland
| | - Antony Lomax
- Center for Proton Therapy, PSI, Switzerland
- Department of Physics, ETH Zurich, Switzerland
| | | | - Christian Pommranz
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tuebingen, Roentgenweg 13, D-72076 Tuebingen, Germany
- Institute for Astronomy and Astrophysics, Eberhard Karls University Tuebingen, Sand 1, D-72076 Tuebingen, Germany
| | - Emilie Roncali
- University of California Davis, Departments of Biomedical Engineering and Radiology, Davis, CA 95616, United States of America
| | - Antoni Rucinski
- Institute of Nuclear Physics Polish Academy of Sciences, Krakow, Poland
| | - Carla Winterhalter
- Center for Proton Therapy, PSI, Switzerland
- Department of Physics, ETH Zurich, Switzerland
| | - Lydia Maigne
- Université Clermont Auvergne, Laboratoire de Physique de Clermont, CNRS, UMR 6533, F-63178 Aubière, France
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31
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Lecoq P. On the way to the 10 ps time-of-flight PET challenge. EUROPEAN PHYSICAL JOURNAL PLUS 2022; 137:964. [PMID: 36043223 PMCID: PMC9411838 DOI: 10.1140/epjp/s13360-022-03159-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
There is a consensus for gathering the multidisciplinary academic and industrial medical imaging community around the ambitious challenge to develop a 10 ps Time-of-Flight PET scanner (TOFPET). The goal is to reduce the radiation dose (currently 5-25 mSv for whole-body PET/CT) and/or scan time (currently > 10 min) by an order of magnitude, with a significant gain in the patient comfort and cost per exam (currently in the range of 1000 € per scan). To achieve this very ambitious goal it is essential to significantly improve the performance of each component of the detection chain: light production, light transport, photodetection, readout electronics. Speeding up progress in this direction is the goal of the challenge and will have an important impact on the development of a new generation of ionization radiation detectors. The possibility to reach 10 ps time-of-flight resolution at small energies (511 keV), as required in finely granulated calorimeters and PET scanners, although extremely challenging, is not limited by physical barriers and a number of disruptive technologies, such as multifunctional heterostructures, combining the high stopping power of well-known scintillators with the ultrafast photon emission resulting from the 1D, 2D or 3D quantum confinement of the excitons in nanocrystals, photonic crystals, photonic fibers, as well as new concepts of 3D digital SiPM structures, open the way to new radiation detector concepts with unprecedented performance.
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Affiliation(s)
- P. Lecoq
- Instituto de Instrumentación Para Imagen Molecular (I3M), Valencia, Spain
- Multiwave Metacrystal S.A., Geneva, Switzerland
- CERN, Geneva, Switzerland
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32
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Schramm G. Reconstruction-free positron emission imaging: Fact or fiction? FRONTIERS IN NUCLEAR MEDICINE (LAUSANNE, SWITZERLAND) 2022; 2:936091. [PMID: 39354988 PMCID: PMC11440944 DOI: 10.3389/fnume.2022.936091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/05/2022] [Indexed: 10/03/2024]
Affiliation(s)
- Georg Schramm
- Division of Nuclear Medicine, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
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33
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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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34
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Krause P, Rogers E, Birowosuto MD, Pei Q, Auffray E, Vasil'ev AN, Bizarri G. Design rules for time of flight Positron Emission Tomography (ToF-PET) heterostructure radiation detectors. Heliyon 2022; 8:e09754. [PMID: 35800729 PMCID: PMC9253360 DOI: 10.1016/j.heliyon.2022.e09754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 05/24/2022] [Accepted: 06/15/2022] [Indexed: 11/25/2022] Open
Abstract
Despite the clinical acceptance of ToF-PET, there is still a gap between the technology's performance and the end-user's needs. Core to bridging this gap is the ability to develop radiation detectors combining a short attenuation length and a sub-nanosecond time response. Currently, the detector of choice, Lu2SiO5:Ce3+ single crystal, is not selected for its ability to answer the performance needs, but as a trade-off between requirements and availability. To bypass the current performance limitations, in particular restricted time response, the concept of the heterostructured detector has been proposed. The concept aims at splitting the scintillation mechanisms across two materials, one acting primarily as an absorber and one as an ultra-fast emitter. If the concept has attracted the interest of the medical and material communities, little has been shown in terms of the benefits/limitations of the approach. Based on Monte Carlo simulations, we present a survey of heterostructure performance versus detector design. The data allow for a clear understanding of the design/performance relationship. This, in turn, enables the establishment of design rules toward the development and optimization of heterostructured detectors that could supersede the current detector technology in the medical imaging field but also across multiple sectors (e.g. high-energy physics, security).
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Optically stimulated luminescence in state-of-the-art LYSO:Ce scintillators enables high spatial resolution 3D dose imaging. Sci Rep 2022; 12:8301. [PMID: 35585168 PMCID: PMC9117671 DOI: 10.1038/s41598-022-12255-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 05/06/2022] [Indexed: 11/08/2022] Open
Abstract
In this contribution, we study the optically stimulated luminescence (OSL) exhibited by commercial \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Lu}_{(2-x)}\hbox {Y}_x\hbox {SiO}_5$$\end{document}Lu(2-x)YxSiO5:Ce crystals. This photon emission mechanism, complementary to scintillation, can trap a fraction of radiation energy deposited in the material and provides sufficient signal to develop a novel post-irradiation 3D dose readout. We characterize the OSL emission through spectrally and temporally resolved measurements and monitor the dose linearity response over a broad range. The measurements show that the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Ce}^{3+}$$\end{document}Ce3+ centers responsible for scintillation also function as recombination centers for the OSL mechanism. The capture to OSL-active traps competes with scintillation originating from the direct non-radiative energy transfer to the luminescent centers. An OSL response on the order of 100 ph/MeV is estimated. We demonstrate the imaging capabilities provided by such an OSL photon yield using a proof-of-concept optical readout method. A 0.1 \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {mm}^3$$\end{document}mm3 spatial resolution for doses as low as 0.5 Gy is projected using a cubic crystal to image volumetric dose profiles. While OSL degrades the intrinsic scintillating performance by reducing the number of scintillation photons emitted following the passage of ionizing radiation, it can encode highly resolved spatial information of the interaction point of the particle. This feature combines ionizing radiation spectroscopy and 3D reusable dose imaging in a single material.
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Zarif Yussefian N, Gaudin E, Lecomte R, Fontaine R. Predicting Small Lesion Detectability for a Small Animal TOF PET Scanner. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2022. [DOI: 10.1109/trpms.2021.3105945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nikta Zarif Yussefian
- Department of Electrical and Computer Engineering and the Interdisciplinary Institute for Technological Innovation 3IT, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Emilie Gaudin
- Sherbrooke Molecular Imaging Center and the Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Roger Lecomte
- Sherbrooke Molecular Imaging Center and the Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Rejean Fontaine
- Department of Electrical and Computer Engineering and the Interdisciplinary Institute for Technological Innovation 3IT, Université de Sherbrooke, Sherbrooke, QC, Canada
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Xue S, Guo R, Bohn KP, Matzke J, Viscione M, Alberts I, Meng H, Sun C, Zhang M, Zhang M, Sznitman R, El Fakhri G, Rominger A, Li B, Shi K. A cross-scanner and cross-tracer deep learning method for the recovery of standard-dose imaging quality from low-dose PET. Eur J Nucl Med Mol Imaging 2022; 49:1843-1856. [PMID: 34950968 PMCID: PMC9015984 DOI: 10.1007/s00259-021-05644-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 11/30/2021] [Indexed: 11/12/2022]
Abstract
PURPOSE A critical bottleneck for the credibility of artificial intelligence (AI) is replicating the results in the diversity of clinical practice. We aimed to develop an AI that can be independently applied to recover high-quality imaging from low-dose scans on different scanners and tracers. METHODS Brain [18F]FDG PET imaging of 237 patients scanned with one scanner was used for the development of AI technology. The developed algorithm was then tested on [18F]FDG PET images of 45 patients scanned with three different scanners, [18F]FET PET images of 18 patients scanned with two different scanners, as well as [18F]Florbetapir images of 10 patients. A conditional generative adversarial network (GAN) was customized for cross-scanner and cross-tracer optimization. Three nuclear medicine physicians independently assessed the utility of the results in a clinical setting. RESULTS The improvement achieved by AI recovery significantly correlated with the baseline image quality indicated by structural similarity index measurement (SSIM) (r = -0.71, p < 0.05) and normalized dose acquisition (r = -0.60, p < 0.05). Our cross-scanner and cross-tracer AI methodology showed utility based on both physical and clinical image assessment (p < 0.05). CONCLUSION The deep learning development for extensible application on unknown scanners and tracers may improve the trustworthiness and clinical acceptability of AI-based dose reduction.
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Affiliation(s)
- Song Xue
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
| | - Rui Guo
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China
| | - Karl Peter Bohn
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
| | - Jared Matzke
- Department of Informatics, Technical University of Munich, Munich, Germany
| | - Marco Viscione
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
| | - Ian Alberts
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
| | - Hongping Meng
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China
| | - Chenwei Sun
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China
| | - Miao Zhang
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China
| | - Min Zhang
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China
| | | | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Axel Rominger
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
| | - Biao Li
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Ruijin Center, Shanghai, China.
| | - Kuangyu Shi
- Department of Nuclear Medicine, University of Bern, Bern, Switzerland
- Department of Informatics, Technical University of Munich, Munich, Germany
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Liu Z, Niu M, Kuang Z, Ren N, Wu S, Cong L, Wang X, Sang Z, Williams C, Yang Y. High resolution detectors for whole-body PET scanners by using dual-ended readout. EJNMMI Phys 2022; 9:29. [PMID: 35445890 PMCID: PMC9023628 DOI: 10.1186/s40658-022-00460-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/08/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Most current whole-body positron emission tomography (PET) scanners use detectors with high timing resolution to measure the time-of-flight of two 511 keV photons, improving the signal-to-noise ratio of PET images. However, almost all current whole-body PET scanners use detectors without depth-encoding capability; therefore, their spatial resolution can be affected by the parallax effect. METHODS In this work, four depth-encoding detectors consisting of LYSO arrays with crystals of 2.98 × 2.98 × 20 mm3, 2.98 × 2.98 × 30 mm3, 1.95 × 1.95 × 20 mm3, and 1.95 × 1.95 × 30 mm3, respectively, were read at both ends, with 6 × 6 mm2 silicon photomultiplier (SiPM) pixels in a 4 × 4 array being used. The timing signals of the detectors were processed individually using an ultrafast NINO application-specific integrated circuit (ASIC) to obtain good timing resolution. The 16 energy signals of the SiPM array were read using a row and column summing circuit to obtain four position-encoding energy signals. RESULTS The four PET detectors provided good flood histograms in which all crystals could be clearly resolved, the crystal energy resolutions measured being 10.2, 12.1, 11.4 and 11.7% full width at half maximum (FWHM), at an average crystal depth of interaction (DOI) resolution of 3.5, 3.9, 2.7, and 3.0 mm, respectively. The depth dependence of the timing of each SiPM was measured and corrected, the timing of the two SiPMs being used as the timing of the dual-ended readout detector. The four detectors provided coincidence time resolutions of 180, 214, 239, and 263 ps, respectively. CONCLUSIONS The timing resolution of the dual-ended readout PET detector was approximately 20% better than that of the single-ended readout detector using the same LYSO array, SiPM array, and readout electronics. The detectors developed in this work used long crystals with small cross-sections and provided good flood histograms, DOI, energy, and timing resolutions, suggesting that they could be used to develop whole-body PET scanners with high sensitivity, uniform high spatial resolution, and high timing resolution.
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Affiliation(s)
- Zheng Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ming Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ning Ren
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - San Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Longhan Cong
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Xiaohui Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ziru Sang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Crispin Williams
- European Centre for Nuclear Research (CERN), Geneva, Switzerland
| | - Yongfeng Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
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Roques-Carmes C, Rivera N, Ghorashi A, Kooi SE, Yang Y, Lin Z, Beroz J, Massuda A, Sloan J, Romeo N, Yu Y, Joannopoulos JD, Kaminer I, Johnson SG, Soljačić M. A framework for scintillation in nanophotonics. Science 2022; 375:eabm9293. [DOI: 10.1126/science.abm9293] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Bombardment of materials by high-energy particles often leads to light emission in a process known as scintillation. Scintillation has widespread applications in medical imaging, x-ray nondestructive inspection, electron microscopy, and high-energy particle detectors. Most research focuses on finding materials with brighter, faster, and more controlled scintillation. We developed a unified theory of nanophotonic scintillators that accounts for the key aspects of scintillation: energy loss by high-energy particles, and light emission by non-equilibrium electrons in nanostructured optical systems. We then devised an approach based on integrating nanophotonic structures into scintillators to enhance their emission, obtaining nearly an order-of-magnitude enhancement in both electron-induced and x-ray–induced scintillation. Our framework should enable the development of a new class of brighter, faster, and higher-resolution scintillators with tailored and optimized performance.
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Affiliation(s)
- Charles Roques-Carmes
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nicholas Rivera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ali Ghorashi
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Steven E. Kooi
- Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yi Yang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, University of Hong Kong, Hong Kong, China
| | - Zin Lin
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Justin Beroz
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aviram Massuda
- Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jamison Sloan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nicolas Romeo
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yang Yu
- Raith America Inc., Troy, NY 12180, USA
| | - John D. Joannopoulos
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ido Kaminer
- Department of Electrical and Computer Engineering, Technion, Haifa 32000, Israel
| | - Steven G. Johnson
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, University of Hong Kong, Hong Kong, China
| | - Marin Soljačić
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Onishi Y, Hashimoto F, Ote K, Ota R. Unbiased TOF estimation using leading-edge discriminator and convolutional neural network trained by single-source-position waveforms. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac508f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 01/31/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. Convolutional neural networks (CNNs) are a strong tool for improving the coincidence time resolution (CTR) of time-of-flight (TOF) positron emission tomography detectors. However, several signal waveforms from multiple source positions are required for CNN training. Furthermore, there is concern that TOF estimation is biased near the edge of the training space, despite the reduced estimation variance (i.e. timing uncertainty). Approach. We propose a simple method for unbiased TOF estimation by combining a conventional leading-edge discriminator (LED) and a CNN that can be trained with waveforms collected from one source position. The proposed method estimates and corrects the time difference error calculated by the LED rather than the absolute time difference. This model can eliminate the TOF estimation bias, as the combination with the LED converts the distribution of the label data from discrete values at each position into a continuous symmetric distribution. Main results. Evaluation results using signal waveforms collected from scintillation detectors show that the proposed method can correctly estimate all source positions without bias from a single source position. Moreover, the proposed method improves the CTR of the conventional LED. Significance. We believe that the improved CTR will not only increase the signal-to-noise ratio but will also contribute significantly to a part of the direct positron emission imaging.
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Shibuya K, Saito H, Tashima H, Yamaya T. Using inverse Laplace transform in positronium lifetime imaging. Phys Med Biol 2022; 67. [PMID: 35008076 DOI: 10.1088/1361-6560/ac499b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/10/2022] [Indexed: 11/11/2022]
Abstract
Positronium (Ps) lifetime imaging is gaining attention to bring out additional biomedical information from positron emission tomography (PET). The lifetime of Psin vivocan change depending on the physical and chemical environments related to some diseases. Due to the limited sensitivity, Ps lifetime imaging may require merging some voxels for statistical accuracy. This paper presents a method for separating the lifetime components in the voxel to avoid information loss due to averaging. The mathematics for this separation is the inverse Laplace transform (ILT), and the authors examined an iterative numerical ILT algorithm using Tikhonov regularization, namely CONTIN, to discriminate a small lifetime difference due to oxygen saturation. The separability makes it possible to merge voxels without missing critical information on whether they contain abnormally long or short lifetime components. The authors conclude that ILT can compensate for the weaknesses of Ps lifetime imaging and extract the maximum amount of information.
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Affiliation(s)
- Kengo Shibuya
- Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan.,Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan
| | - Haruo Saito
- Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
| | - Hideaki Tashima
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan
| | - Taiga Yamaya
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan
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Total-body PET. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00118-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Lin Z, Lv S, Yang Z, Qiu J, Zhou S. Structured Scintillators for Efficient Radiation Detection. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2102439. [PMID: 34761546 PMCID: PMC8805559 DOI: 10.1002/advs.202102439] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/04/2021] [Indexed: 05/02/2023]
Abstract
Scintillators, which can convert high-energy ionizing radiation into visible light, have been serving as the core component in radiation detectors for more than a century of history. To address the increasing application demands along with the concern on nuclear security, various strategies have been proposed to develop a next-generation scintillator with a high performance in past decades, among which the novel approach via structure control has received great interest recently due to its high feasibility and efficiency. Herein, the concept of "structure engineering" is proposed for the exploration of this type of scintillators. Via internal or external structure design with size ranging from micro size to macro size, this promising strategy cannot only improve scintillator performance, typically radiation stopping power and light yield, but also extend its functionality for specific applications such as radiation imaging and therapy, opening up a new range of material candidates. The research and development of various types of structured scintillators are reviewed. The current state-of-the-art progresses on structure design, fabrication techniques, and the corresponding applications are discussed. Furthermore, an outlook focusing on the current challenges and future development is proposed.
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Affiliation(s)
- Ziyu Lin
- State Key Laboratory of Luminescent Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesGuangzhou510640China
| | - Shichao Lv
- State Key Laboratory of Luminescent Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesGuangzhou510640China
| | - Zhongmin Yang
- State Key Laboratory of Luminescent Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesGuangzhou510640China
| | - Jianrong Qiu
- College of Optical Science and EngineeringZhejiang UniversityHangzhou310027China
| | - Shifeng Zhou
- State Key Laboratory of Luminescent Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesGuangzhou510640China
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Konstantinou G, Lecoq P, Benlloch JM, Gonzalez AJ. Metascintillators for Ultrafast Gamma Detectors: A Review of Current State and Future Perspectives. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2022. [DOI: 10.1109/trpms.2021.3069624] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Moskal P, Stępień EŁ. New trends in theranostics. BIO-ALGORITHMS AND MED-SYSTEMS 2021. [DOI: 10.1515/bams-2021-0204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Paweł Moskal
- Faculty of Physics, Astronomy and Applied Computer Science , M. Smoluchowski Institute of Physics, Jagiellonian University , Krakow , Poland
- Total-Body Jagiellonian-PET Laboratory , Jagiellonian University , Kraków , Poland
- Theranostics Center , Jagiellonian University , Kraków , Poland
| | - Ewa Ł. Stępień
- Faculty of Physics, Astronomy and Applied Computer Science , M. Smoluchowski Institute of Physics, Jagiellonian University , Krakow , Poland
- Total-Body Jagiellonian-PET Laboratory , Jagiellonian University , Kraków , Poland
- Theranostics Center , Jagiellonian University , Kraków , Poland
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Matulewicz T. Radioactive nuclei for β
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γ PET and theranostics: selected candidates. BIO-ALGORITHMS AND MED-SYSTEMS 2021. [DOI: 10.1515/bams-2021-0142] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Positron emission tomography (PET) is an established medical diagnostic imaging method. Continuous improvements are aimed at refining image reconstruction, reducing the amount of radioactive tracer and combining with targeted therapy. Time-of-flight (TOF)-PET provides the localization of the tracer through improved time resolution, nuclear physics may contribute to this goal via selection of radioactive nuclei emitting additional γ-rays. This additional radiation, when properly detected, localizes the decay of the tracer at the line of response (LoR) determined by two detected 511 keV quanta. Selected candidates are presented. Some are particularly interesting, as they are strong candidates for theranostic applications.
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Děcká K, Král J, Hájek F, Průša P, Babin V, Mihóková E, Čuba V. Scintillation Response Enhancement in Nanocrystalline Lead Halide Perovskite Thin Films on Scintillating Wafers. NANOMATERIALS 2021; 12:nano12010014. [PMID: 35009964 PMCID: PMC8746850 DOI: 10.3390/nano12010014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 12/16/2022]
Abstract
Lead halide perovskite nanocrystals of the formula CsPbBr3 have recently been identified as potential time taggers in scintillating heterostructures for time-of-flight positron emission tomography (TOF-PET) imaging thanks to their ultrafast decay kinetics. This study investigates the potential of this material experimentally. We fabricated CsPbBr3 thin films on scintillating GGAG:Ce (Gd2.985Ce0.015Ga2.7Al2.3O12) wafer as a model structure for the future sampling detector geometry. We focused this study on the radioluminescence (RL) response of this composite material. We compare the results of two spin-coating methods, namely the static and the dynamic process, for the thin film preparation. We demonstrated enhanced RL intensity of both CsPbBr3 and GGAG:Ce scintillating constituents of a composite material. This synergic effect arises in both the RL spectra and decays, including decays in the short time window (50 ns). Consequently, this study confirms the applicability of CsPbBr3 nanocrystals as efficient time taggers for ultrafast timing applications, such as TOF-PET.
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Affiliation(s)
- Kateřina Děcká
- Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic; (J.K.); (V.Č.)
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic; (F.H.); (P.P.); (V.B.); (E.M.)
- Correspondence:
| | - Jan Král
- Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic; (J.K.); (V.Č.)
| | - František Hájek
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic; (F.H.); (P.P.); (V.B.); (E.M.)
- Department of Solid State Engineering, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic
| | - Petr Průša
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic; (F.H.); (P.P.); (V.B.); (E.M.)
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic
| | - Vladimir Babin
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic; (F.H.); (P.P.); (V.B.); (E.M.)
| | - Eva Mihóková
- Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic; (F.H.); (P.P.); (V.B.); (E.M.)
- Department of Solid State Engineering, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic
| | - Václav Čuba
- Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic; (J.K.); (V.Č.)
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48
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Kwon SI, Ota R, Berg E, Hashimoto F, Nakajima K, Ogawa I, Tamagawa Y, Omura T, Hasegawa T, Cherry SR. Ultrafast timing enables reconstruction-free positron emission imaging. NATURE PHOTONICS 2021; 15:914-918. [PMID: 35663419 PMCID: PMC9165659 DOI: 10.1038/s41566-021-00871-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/04/2021] [Indexed: 05/07/2023]
Abstract
X-ray and gamma-ray photons are widely used for imaging but require a mathematical reconstruction step, known as tomography, to produce cross-sectional images from the measured data. Theoretically, the back-to-back annihilation photons produced by positron-electron annihilation can be directly localized in three-dimensional space using time-of-flight information without tomographic reconstruction. However, this has not yet been demonstrated due to the insufficient timing performance of available radiation detectors. Here, we develop techniques based on detecting prompt Cerenkov photons, which when combined with a convolutional neural network for timing estimation resulted in an average timing precision of 32 picoseconds, corresponding to a spatial precision of 4.8 mm. We show this is sufficient to produce cross-sectional images of a positron-emitting radionuclide directly from the detected coincident annihilation photons, without using any tomographic reconstruction algorithm. The reconstruction-free imaging demonstrated here directly localizes positron emission, and frees the design of an imaging system from the geometric and sampling constraints that normally present for tomographic reconstruction.
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Affiliation(s)
- Sun Il Kwon
- Department of Biomedical Engineering, University of California; Davis, USA
| | - Ryosuke Ota
- Central Research Laboratory, Hamamatsu Photonics K.K.; Hamamatsu, Japan
| | - Eric Berg
- Department of Biomedical Engineering, University of California; Davis, USA
| | - Fumio Hashimoto
- Central Research Laboratory, Hamamatsu Photonics K.K.; Hamamatsu, Japan
| | | | - Izumi Ogawa
- Faculty of Engineering, University of Fukui; Fukui, Japan
| | | | - Tomohide Omura
- Central Research Laboratory, Hamamatsu Photonics K.K.; Hamamatsu, Japan
| | - Tomoyuki Hasegawa
- School of Allied Health Sciences, Kitasato University; Kitasato, Japan
| | - Simon R. Cherry
- Department of Biomedical Engineering, University of California; Davis, USA
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49
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Krishnamoorthy S, Teo BKK, Zou W, McDonough J, Karp JS, Surti S. A proof-of-concept study of an in-situ partial-ring time-of-flight PET scanner for proton beam verification. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2021; 5:694-702. [PMID: 34746539 DOI: 10.1109/trpms.2020.3044326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Development of a PET system capable of in-situ imaging requires a design that can accommodate the proton treatment beam nozzle. Among the several PET instrumentation approaches developed thus far, the dual-panel PET scanner is often used as it is simpler to develop and integrate within the proton therapy gantry. Partial-angle coverage of these systems can however lead to limited-angle artefacts in the reconstructed PET image. We have previously demonstrated via simulations that time-of-flight (TOF) reconstruction reduces the artifacts accompanying limited-angle data, and permits proton range measurement with 1-2 mm accuracy and precision. In this work we show measured results from a small proof-of-concept dual-panel PET system that uses TOF information to reconstruct PET data acquired after proton irradiation. The PET scanner comprises of two detector modules, each comprised of an array of 4×4×30 mm3 lanthanum bromide scintillator. Measurements are performed with an oxygen-rich gel-water, an adipose tissue equivalent material, and in vitro tissue phantoms. For each phantom measurement, 2 Gy dose was deposited using 54 - 100 MeV proton beams. For each phantom, a Monte Carlo simulation generating the expected distribution of PET isotope from the corresponding proton irradiation was also performed. Proton range was calculated by drawing multiple depth-profiles over a central region encompassing the proton dose deposition. For each profile, proton range was calculated using two techniques (a) 50% pick-off from the distal edge of the profile, and (b) comparing the measured and Monte Carlo profile to minimize the absolute sum of differences over the entire profile. A 10 min PET acquisition acquired with minimal delay post proton-irradiation is compared with a 10 min PET scan acquired after a 20 min delay. Measurements show that PET acquisition with minimal delay is necessary to collect 15O signal, and maximize 11C signal collection with a short PET acquisition. In comparison with the 50% pick-off technique, the shift technique is more robust and offers better precision in measuring the proton range for the different phantoms. Range measurements from PET images acquired with minimal delay, and the shift technique demonstrate the ability to achieve <1.5 mm accuracy and precision in estimating proton range.
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Affiliation(s)
| | - Boon-Keng K Teo
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Wei Zou
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - James McDonough
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Joel S Karp
- Departments of Radiology and Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Suleman Surti
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104 USA
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50
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Cucarella N, Barrio J, Lamprou E, Valladares C, Benlloch JM, Gonzalez AJ. Timing evaluation of a PET detector block based on semi-monolithic LYSO crystals. Med Phys 2021; 48:8010-8023. [PMID: 34723380 DOI: 10.1002/mp.15318] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/25/2021] [Accepted: 10/15/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Detectors for positron emission tomography (PET) typically use two types of scintillation crystals, pixelated or monolithic. A variant of these types of scintillators are the so-called semi-monolithic crystals. They consist of a monolithic crystal segmented in one direction in pieces called slabs. These scintillators have the potential to successfully combine the benefits of pixelated and monolithic configurations, providing good timing and spatial resolutions as well as the capacity to decode the depth of interaction (DOI) information. In this work, the timing performance of a detector based on semi-monolithic crystals was studied in depth. The energy response was also evaluated. METHODS The semi-monolithic detector consists of 1 × 24 LYSO slabs of 25.4 × 12 × 0.95 mm3 each. The bottom surface of the slabs is coupled to an array of 8 × 8 silicon photomultipliers (SiPMs) of 3 × 3 mm2 active area, 50 μm cell size and 3.2 mm pitch. The 64 output signals were independently readout by the TOFPET2 ASIC. In order to achieve the best coincidence time resolution (CTR), four different time walk corrections were tested. Additional work investigated the best method of combining the timestamps belonging to the same event. RESULTS The resolvability of the slabs in the measured flood maps improves with the thickness of a light guide placed in between the scintillators and photosensors. The energy resolution does not change significantly with values as good as 13.7%. Regarding the CTR, values of 335.8, 363, 369.8, and 402.5 ps have been obtained for the whole detector for no light guide, 0.5, 1.0, and 1.5 mm thickness light guide cases, respectively. These values further improve to 276.1, 302.6, 305.6 and 336.2 ps, respectively, when energy-weighted averaging of timestamps is applied. CONCLUSIONS We have shown both an excellent timing resolution and good energy resolution for a PET detector based on semi-monolithic crystals. The use of light guides of different thicknesses does not significantly affect the energy resolution of the whole detector, but the timing capabilities slightly worsen with the increasing thickness of the light guide.
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Affiliation(s)
- Neus Cucarella
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
| | - John Barrio
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
| | - Efthymios Lamprou
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
| | - Celia Valladares
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
| | - Jose M Benlloch
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
| | - Antonio J Gonzalez
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro mixto CSIC-Universitat Politècnica de València, Valencia, 46022, Spain
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