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Miyata K, Ogawara R, Ishikawa M. Improvement of Crystal Identification Accuracy for Depth-of-Interaction Detector System with Peak-to-Charge Discrimination Method. SENSORS (BASEL, SWITZERLAND) 2023; 23:4584. [PMID: 37430498 DOI: 10.3390/s23104584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/06/2023] [Accepted: 05/07/2023] [Indexed: 07/12/2023]
Abstract
In positron emission tomography (PET), parallax errors degrade spatial resolution. The depth of interaction (DOI) information provides the position in the depth of the scintillator interacting with the γ-rays, thus reducing parallax errors. A previous study developed a Peak-to-Charge discrimination (PQD), which can separate spontaneous alpha decay in LaBr3:Ce. Since decay constant of GSO:Ce depends on Ce concentration, the PQD is expected to discriminate GSO:Ce scintillators with different Ce concentration. In this study, the PQD-based DOI detector system was developed, which can be processed online and implemented in PET. A detector was composed of four layers of GSO:Ce crystals and a PS-PMT. The four crystals were obtained from both the top and bottom of ingots with a nominal Ce concentration of 0.5 mol% and 1.5 mol%. The PQD was implemented on the Xilinx Zynq-7000 SoC board with 8ch Flash ADC to gain real-time processing, flexibility, and expandability. The results showed that the mean Figure of Merits in 1D between four scintillators are 1.5, 0.99, 0.91 for layers between 1st-2nd, 2nd-3rd, and 3rd-4th respectively, and the mean Error Rate in 1D between four scintillators are 3.50%, 2.96%, 13.3%, and 1.88% for layers 1, 2, 3, and 4, respectively. In addition, the introduction of the 2D PQDs resulted in the mean Figure of Merits in 2D greater than 0.9 and the mean Error Rate in 2D less than 3% in all layers.
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Affiliation(s)
- Kento Miyata
- Graduate School of Biomedical Science and Engineering, Hokkaido University, N-15 W-7 Kita-ku, Sapporo 060-8638, Japan
| | - Ryo Ogawara
- Institute for Chemical Research, Kyoto University, Gokasho, Uji 611-0011, Japan
| | - Masayori Ishikawa
- Faculty of Health Sciences, Hokkaido University, N-12 W-5 Kita-ku, Sapporo 060-0812, Japan
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Loignon-Houle F, Gundacker S, Toussaint M, Camirand Lemyre F, Auffray E, Fontaine R, Charlebois SA, Lecoq P, Lecomte R. DOI estimation through signal arrival time distribution: a theoretical description including proof of concept measurements. Phys Med Biol 2021; 66. [PMID: 33831858 DOI: 10.1088/1361-6560/abf604] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 04/08/2021] [Indexed: 11/12/2022]
Abstract
The challenge to reach 10 ps coincidence time resolution (CTR) in time-of-flight positron emission tomography (TOF-PET) is triggering major efforts worldwide, but timing improvements of scintillation detectors will remain elusive without depth-of-interaction (DOI) correction in long crystals. Nonetheless, this momentum opportunely brings up the prospect of a fully time-based DOI estimation since fast timing signals intrinsically carry DOI information, even with a traditional single-ended readout. Consequently, extracting features of the detected signal time distribution could uncover the spatial origin of the interaction and in return, provide enhancement on the timing precision of detectors. We demonstrate the validity of a time-based DOI estimation concept in two steps. First, experimental measurements were carried out with current LSO:Ce:Ca crystals coupled to FBK NUV-HD SiPMs read out by fast high-frequency electronics to provide new evidence of a distinct DOI effect on CTR not observable before with slower electronics. Using this detector, a DOI discrimination using a double-threshold scheme on the analog timing signal together with the signal intensity information was also developed without any complex readout or detector modification. As a second step, we explored by simulation the anticipated performance requirements of future detectors to efficiently estimate the DOI and we proposed four estimators that exploit either more generic or more precise features of the DOI-dependent timestamp distribution. A simple estimator using the time difference between two timestamps provided enhanced CTR. Additional improvements were achieved with estimators using multiple timestamps (e.g. kernel density estimation and neural network) converging to the Cramér-Rao lower bound developed in this work for a time-based DOI estimation. This two-step study provides insights on current and future possibilities in exploiting the timing signal features for DOI estimation aiming at ultra-fast CTR while maintaining detection efficiency for TOF PET.
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Affiliation(s)
- Francis Loignon-Houle
- Sherbrooke Molecular Imaging Center, CRCHUS, and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Canada
| | - Stefan Gundacker
- CERN, 1211 Geneva 23, Switzerland.,UniMIB, Piazza dell'Ateneo Nuovo, I-120126, Milano, Italy
| | - Maxime Toussaint
- Department of Computer Science, Université de Sherbrooke, Sherbrooke, Canada
| | | | | | - Réjean Fontaine
- Interdisciplinary Institute for Technological Innovation and Department of Electrical and Computer Engineering, Université de Sherbrooke, Sherbrooke, Canada
| | - Serge A Charlebois
- Interdisciplinary Institute for Technological Innovation and Department of Electrical and Computer Engineering, Université de Sherbrooke, Sherbrooke, Canada
| | - Paul Lecoq
- CERN, 1211 Geneva 23, Switzerland.,Polytechnic University, I3M laboratory, Valencia, Spain
| | - Roger Lecomte
- Sherbrooke Molecular Imaging Center, CRCHUS, and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, Canada
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Xu Y, Zhao M, Zhou D, Zheng T, Zhang H. The application of multifunctional nanomaterials in Alzheimer's disease: A potential theranostics strategy. Biomed Pharmacother 2021; 137:111360. [PMID: 33582451 DOI: 10.1016/j.biopha.2021.111360] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 01/13/2021] [Accepted: 02/02/2021] [Indexed: 12/15/2022] Open
Abstract
By virtue of their small size, nanomaterials can cross the blood-brain barrier and, when modified to target specific cells or regions, can achieve high bioavailability at the intended site of action. Modified nanomaterials are therefore promising agents for the diagnosis and treatment of neurodegenerative diseases such as Alzheimer's disease (AD). Here we review the roles and mechanisms of action of nanomaterials in AD. First, we discuss the general characteristics of nanomaterials and their application to nanomedicine. Then, we summarize recent studies on the diagnosis and treatment of AD using modified nanomaterials. These studies indicate that using nanomaterials is a potential strategy for AD treatment by slowing the progression of AD through enhanced therapeutic effects.
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Affiliation(s)
- Yilan Xu
- Neurodegeneration and Neuroregeneration Laboratory, Department of Basic Medicine, School of Medicine, Shaoxing University, Shaoxing 312000, Zhejiang, China
| | - Manna Zhao
- Neurodegeneration and Neuroregeneration Laboratory, Department of Basic Medicine, School of Medicine, Shaoxing University, Shaoxing 312000, Zhejiang, China
| | - Dongming Zhou
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China
| | - Tingting Zheng
- Department of Neurology, The First Affiliated Hospital of ZheJiang Chinese Medical University, Zhejiang Provincial Hospital of TCM, Hangzhou 310058, Zhejiang, China
| | - Heng Zhang
- Neurodegeneration and Neuroregeneration Laboratory, Department of Basic Medicine, School of Medicine, Shaoxing University, Shaoxing 312000, Zhejiang, China.
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Kuang Z, Wang X, Ren N, Wu S, Gao J, Zeng T, Gao D, Zhang C, Sang Z, Hu Z, Du J, Liang D, Liu X, Zheng H, Yang Y. Design and performance of SIAT aPET: a uniform high-resolution small animal PET scanner using dual-ended readout detectors. Phys Med Biol 2020; 65:235013. [PMID: 32992302 DOI: 10.1088/1361-6560/abbc83] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this work, a small animal PET scanner named SIAT aPET was developed using dual-ended readout depth encoding detectors to simultaneously achieve high spatial resolution and high sensitivity. The scanner consists of four detector rings with 12 detector modules per ring; the ring diameter is 111 mm and the axial field of view (FOV) is 105.6 mm. The images are reconstructed using an ordered subset expectation maximization (OSEM) algorithm. The spatial resolution of the scanner was measured by using a 22Na point source at the center axial FOV with different radial offsets. The sensitivity of the scanner was measured at center axis of the scanner with different axial positions. The count rate performance of the system was evaluated by scanning mouse-sized and rat-sized phantoms. An ultra-micro hot-rods phantom and two mice injected with 18F-NaF and 18F-FDG were scanned on the scanner. An average depth of interaction (DOI) resolution of 1.96 mm, energy resolution of 19.1% and timing resolution of 1.20 ns were obtained for the detector. Average spatial resolutions of 0.82 mm and 1.16 mm were obtained up to a distance of 30 mm radially from the center of the FOV when reconstructing a point source in 1% and 10% warm backgrounds, respectively, using OSEM reconstruction with 16 subsets and 10 iterations. Sensitivities of 16.0% and 11.9% were achieved at center of the scanner for energy windows of 250-750 keV and 350-750 keV respectively. Peak noise equivalent count rates (NECRs) of 324 kcps and 144 kcps were obtained at an activity of 26.4 MBq for the mouse-sized and rat-sized phantoms. Rods of 1.0 mm diameter can be visually resolved from the image of the ultra-micro hot-rods phantom. The capability of the scanner was demonstrated by high quality in-vivo mouse images.
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Affiliation(s)
- Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China. Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China. Authors have contributed equally to this work
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Selfridge A, Cherry S, Badawi R. Characterization of four readout circuits for an MR compatible, preclinical PET detector. Phys Med Biol 2020; 65:125008. [PMID: 32340015 PMCID: PMC10473842 DOI: 10.1088/1361-6560/ab8d76] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We are building a high sensitivity preclinical PET/MRI insert using a highly multiplexed light sharing PET module. Each module incorporates four 19 × 19 arrays of 1 × 1 × 20 mm3 LYSO crystals with dual-ended DOI encoding readout, requiring 32 readout channels for positioning and eight channels for timing. These constraints necessitate compact, robust electronics for digitization. We have characterized four linearized time-over-threshold circuits based on these detector requirements. The four circuits allow for high channel density and can digitize signals from highly multiplexed light sharing detectors. Each circuit digitizes one channel of a multiplexed SiPM array, yielding a binary output that interfaces directly with an FPGA. Using the optimal circuit, we have characterized the performance of a pair of PET modules. The four circuits were characterized based on linearity of the 22Na photopeak positions and energy resolution at 511 keV, as well as separation of elements in a 10 × 10 array of 1.2 mm LYSO crystals coupled with a specular reflector. Practical measures of performance were comparable to those obtained with a DRS evaluation board, which served as a reference acquisition system. The ratio of the 22Na photopeak positions was 2.0 for each circuit and the reference system, implying 20% saturation due to the SiPM. PET energy resolution of the optimal circuit was 11.8% FWHM for a single crystal versus 12.6% for the reference system, and crystals were equally well separated in all cases. PCBs implementing the optimal readout circuit were fabricated and used to construct two complete detector modules. Crystals in each of the four blocks in the module were well resolved, with a mean energy resolution of 24.4 ± 4.7%. Two modules operating in coincidence showed a single detector timing resolution of 3.0 ns, which is appropriate for preclinical applications.
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Affiliation(s)
- Aaron Selfridge
- Department of Biomedical Engineering, University of California, Davis, United States of America
| | - Simon Cherry
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
| | - Ramsey Badawi
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
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