1
|
Park H, Yi M, Lee JS. Silicon photomultiplier signal readout and multiplexing techniques for positron emission tomography: a review. Biomed Eng Lett 2022; 12:263-283. [PMID: 35892029 PMCID: PMC9308856 DOI: 10.1007/s13534-022-00234-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/21/2022] [Accepted: 05/30/2022] [Indexed: 12/03/2022] Open
Abstract
In recent years, silicon photomultiplier (SiPM) is replacing the photomultiplier tube (PMT) in positron emission tomography (PET) systems due to its superior properties, such as fast single-photon timing response, small gap between adjacent photosensitive pixels in the array, and insensitivity to magnetic fields. One of the technical challenges when developing SiPM-based PET systems or other position-sensitive radiation detectors is the large number of output channels coming from the SiPM array. Therefore, various signal multiplexing methods have been proposed to reduce the number of output channels and the load on the subsequent data acquisition (DAQ) system. However, the large PN-junction capacitance and quenching resistance of the SiPM yield undesirable resistance-capacitance delay when multiple SiPMs are combined, which subsequently causes the accumulation of dark counts and signal fluctuation of SiPMs. Therefore, without proper SiPM signal handling and processing, the SiPMs may yield worse timing characteristics than the PMTs. This article reviews the evolution of signal readout and multiplexing methods for the SiPM. In this review, we focus primarily on analog electronics for SiPM signal multiplexing, which allows for the reduction of DAQ channels required for the SiPM-based position-sensitive detectors used in PET and other radiation detector systems. Although the applications of most technologies described in the article are not limited to PET systems, the review highlights efforts to improve the physical performance (e.g. spatial, energy, and timing resolutions) of PET detectors and systems.
Collapse
Affiliation(s)
- Haewook Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 South Korea
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
| | - Minseok Yi
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
- Interdisciplinary Program in Bioengineering, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Integrated Major in Innovative Medical Science, Seoul National University College of Engineering, Seoul, 03080 South Korea
| | - Jae Sung Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 South Korea
- Department of Nuclear Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul, 03080 South Korea
- Interdisciplinary Program in Bioengineering, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Integrated Major in Innovative Medical Science, Seoul National University College of Engineering, Seoul, 03080 South Korea
- Brightonix Imaging Inc, Seoul, 04782 South Korea
| |
Collapse
|
2
|
Calva-Coraza E, Alva-Sánchez H, Murrieta-Rodríguez T, Martínez-Dávalos A, Rodríguez-Villafuerte M. Optimization of a large-area detector-block based on SiPM and pixelated LYSO crystal arrays. Phys Med 2017; 42:19-27. [PMID: 29173915 DOI: 10.1016/j.ejmp.2017.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 10/19/2022] Open
Abstract
We present the performance evaluation of a large-area detector module based on the ArrayC-60035-64P, an 8×8 array of tileable, 7.2mm pitch, silicon photomultipliers (SiPM) by SensL, covering a total area of 57.4mm×57.4mm. We characterized the ArrayC-60035-64P, operating at room temperature, using LYSO pixelated crystal arrays of different pitch sizes (1.075, 1.430, 1.683, 2.080 and 2.280mm) to determine the resolvable crystal size. After an optimization process, a 7mm thick coupling light guide was used for all crystal pitches. To identify the interaction position a 16-channel (8 columns, 8 rows) symmetric charge division (SCD) readout board together with a center-of-gravity algorithm was used. Based on this, we assembled the detector modules using a 40×40 LYSO, 1.43mm pitch array, covering the total detector area. Calibration was performed using a 137Cs source resulting in excellent crystal maps with minor geometric distortion, a mean 4.1 peak-to-valley ratio and 9.6% mean energy resolution for 662keV photons in the central region. The resolvability index was calculated in the x and y directions with values under 0.42 in all cases. We show that these large area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, without processing a big number of signals, attaining excellent energy resolution and detector uniformity.
Collapse
Affiliation(s)
- E Calva-Coraza
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000, Mexico City, Mexico
| | - H Alva-Sánchez
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000, Mexico City, Mexico.
| | - T Murrieta-Rodríguez
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000, Mexico City, Mexico
| | - A Martínez-Dávalos
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000, Mexico City, Mexico
| | - M Rodríguez-Villafuerte
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000, Mexico City, Mexico
| |
Collapse
|
3
|
Yamamoto S. Effective Radiofrequency Attenuation Methods to Reduce the Interference Between PET and MRI Systems. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2017. [DOI: 10.1109/trpms.2017.2729620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
4
|
Pratiwi E, Leem HT, Park JH, Choi Y, Yamamoto S, Kamada K, Yoshikawa A, Yeom JY. Performance of a 0.4 mm Pixelated Ce:GAGG Block Detector With Digital Silicon Photomultiplier. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2017. [DOI: 10.1109/tns.2016.2620480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
5
|
Raylman RR, Stolin AV, Martone PF, Smith MF. TandemPET- A High Resolution, Small Animal, Virtual Pinhole-Based PET Scanner: Initial Design Study. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2016; 63:75-83. [PMID: 27041767 PMCID: PMC4813808 DOI: 10.1109/tns.2015.2482459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Mice are the perhaps the most common species of rodents used in biomedical research, but many of the current generation of small animal PET scanners are non-optimal for imaging these small rodents due to their relatively low resolution. Consequently, a number of researchers have investigated the development of high-resolution scanners to address this need. In this investigation, the design of a novel, high-resolution system based on the dual-detector, virtual-pinhole PET concept was explored via Monte Carlo simulations. Specifically, this system, called TandemPET, consists of a 5 cm × 5 cm high-resolution detector made-up of a 90 × 90 array of 0.5 mm × 0.5 mm × 10 mm (pitch= 0.55 mm) LYSO detector elements in coincidence with a lower resolution detector consisting of a 68 × 68 array of 1.5 mm × 1.5 mm × 10 mm LYSO detector elements (total size= 10.5 cm × 10.5 cm). Analyses indicated that TandemPET's optimal geometry is to position the high-resolution detector 3 cm from the center-of-rotation, with the lower resolution detector positioned 9 cm from center. Measurements using modified NEMA NU4-2008-based protocols revealed that the spatial resolution of the system is ~0.5 mm FWHM, after correction of positron range effects. Peak sensitivity is 2.1%, which is comparable to current small animal PET scanners. Images from a digital mouse brain phantom demonstrated the potential of the system for identifying important neurological structures.
Collapse
Affiliation(s)
- Raymond R. Raylman
- Center for Advanced Imaging, Department of Radiology at West Virginia University
| | - Alexander V. Stolin
- Center for Advanced Imaging, Department of Radiology at West Virginia University
| | - Peter F. Martone
- Center for Advanced Imaging, Department of Radiology at West Virginia University
| | - Mark F. Smith
- Department of Diagnostic Radiology and Nuclear Medicine at the University of Maryland School of Medicine
| |
Collapse
|
6
|
Du J, Schmall JP, Di K, Yang Y, Judenhofer M, Bec J, Buckley S, Jackson C, Cherry SR. Design and optimization of a high-resolution PET detector module for small-animal PET based on a 12 × 12 silicon photomultiplier array. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/4/045003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
7
|
Du J, Schmall JP, Yang Y, Di K, Roncali E, Mitchell GS, Buckley S, Jackson C, Cherry SR. Evaluation of Matrix9 silicon photomultiplier array for small-animal PET. Med Phys 2015; 42:585. [PMID: 25652479 DOI: 10.1118/1.4905088] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL's front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm(2) and the total size of the detector head is 47.8 × 46.3 mm(2). Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). METHODS Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0-32.5 V in 0.5 V intervals) and at different temperatures (5 °C-25 °C in 5 °C degree steps) to find the optimal operating conditions. RESULTS The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. CONCLUSIONS In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.
Collapse
Affiliation(s)
- Junwei Du
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Jeffrey P Schmall
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Yongfeng Yang
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Kun Di
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Emilie Roncali
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Gregory S Mitchell
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616
| | - Steve Buckley
- SensL Technologies Ltd., 6800 Airport Business Park, Cork, Ireland
| | - Carl Jackson
- SensL Technologies Ltd., 6800 Airport Business Park, Cork, Ireland
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California, 95616
| |
Collapse
|
8
|
Lee MS, Lee JS. Depth-of-interaction measurement in a single-layer crystal array with a single-ended readout using digital silicon photomultiplier. Phys Med Biol 2015; 60:6495-514. [DOI: 10.1088/0031-9155/60/16/6495] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
9
|
Schmall JP, Du J, Judenhofer MS, Dokhale P, Christian J, McClish M, Shah KS, Cherry SR. A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2014; 61:1074-1083. [PMID: 25473125 PMCID: PMC4249698 DOI: 10.1109/tns.2014.2302635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm3 LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing methods and by accounting for changes in the shape of the signals from PS-SSPMs.
Collapse
Affiliation(s)
- Jeffrey P Schmall
- Department of Biomedical Engineering, University of California - Davis, CA, 95616 USA
| | - Junwei Du
- Department of Biomedical Engineering, University of California - Davis, CA, 95616 USA
| | - Martin S Judenhofer
- Department of Biomedical Engineering, University of California - Davis, CA, 95616 USA
| | | | | | - Mickel McClish
- Radiation Monitoring Devices Inc., Watertown, MA, 02472 USA
| | - Kanai S Shah
- Radiation Monitoring Devices Inc., Watertown, MA, 02472 USA
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California - Davis, CA, 95616 USA
| |
Collapse
|
10
|
Yamamoto S, Watabe H, Kanai Y, Watabe T, Kato K, Hatazawa J. Development of an ultrahigh resolution Si-PM based PET system for small animals. Phys Med Biol 2013; 58:7875-88. [PMID: 24145308 DOI: 10.1088/0031-9155/58/21/7875] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Since a high resolution PET system is needed for small animal imaging, especially for mouse studies, we developed a new small animal PET system that decreased the size of the scintillators to less than 1 mm. Our developed PET system used 0.5 × 0.7 × 5 mm(3) LYSO pixels arranged in an 11 × 13 matrix to form a block with a 0.1 mm BaSO4 reflector between the pixels. Two LYSO blocks were optically coupled to two optical fiber based angled image guides. These LYSO blocks and image guides were coupled to a Si-PM array (Hamamatsu MPPC S11064-050P) to form a block detector. Eight block detectors (16 LYSO blocks) were arranged in a 34 mm inner diameter ring to form a small animal PET system. The block detector showed good separation for the 22 × 13 LYSO pixels in the two-dimensional position histogram. The energy resolution was 20% full-with at half-maximum (FWHM) for 511 keV gamma photons. The transaxial resolution reconstructed by filtered backprojection was 0.71 to 0.75 mm FWHM and the axial resolution was 0.70 mm. The point source sensitivity was 0.24% at the central axial field-of-view. High resolution mouse images were obtained using our PET system. The developed ultrahigh resolution PET system showed attractive images for small animal studies and has a potential to provide new findings in molecular imaging researches.
Collapse
Affiliation(s)
- Seiichi Yamamoto
- Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Japan
| | | | | | | | | | | |
Collapse
|
11
|
Rodríguez-Villafuerte M, Yang Y, Cherry SR. A Monte Carlo investigation of the spatial resolution performance of a small-animal PET scanner designed for mouse brain imaging studies. Phys Med 2013; 30:76-85. [PMID: 23566478 DOI: 10.1016/j.ejmp.2013.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/27/2013] [Accepted: 03/13/2013] [Indexed: 11/17/2022] Open
Abstract
Our laboratory has developed PET detectors with depth-encoding accuracy of ∼2 mm based on finely pixelated crystals with a tapered geometry, readout at both ends with position-sensitive avalanche photodiodes (PSAPDs). These detectors are currently being used in our laboratory to build a one-ring high resolution PET scanner for mouse brain imaging studies. Due to the inactive areas around the PSAPDs, large gaps exist between the detector modules which can degrade the image spatial resolution obtained using analytical reconstruction with filtered backprojection (FBP). In this work, the Geant4-based GATE Monte Carlo package was used to assist in determining whether gantry rotation was necessary and to assess the expected spatial resolution of the system. The following factors were investigated: rotating vs. static gantry modes with and without compensation of missing data using the discrete cosine transform (DCT) method, two levels of depth-encoding, and positron annihilation effects for (18)F. Our results indicate that while the static scanner produces poor quality FBP images with streak and ring artifacts, the image quality was greatly improved after compensation of missing data. The simulation indicates that the expected FWHM system spatial resolution is 0.70 ± 0.05 mm, which approaches the predicted limit of 0.5 mm FWHM due to positron range, photon non-colinearity and physical detector element size effects. We conclude that excellent reconstructed resolution without gantry rotation is possible even using FBP if the gaps are appropriately handled and that this design can approach the resolution limits set by positron annihilation physics.
Collapse
Affiliation(s)
- Mercedes Rodríguez-Villafuerte
- Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, 01000 Mexico D. F., Mexico; Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Yongfeng Yang
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA
| |
Collapse
|
12
|
Ito M, Lee MS, Lee JS. Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout. Phys Med Biol 2013; 58:1269-82. [PMID: 23384966 DOI: 10.1088/0031-9155/58/5/1269] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We propose a depth-of-interaction (DOI)-encoding method to extract continuous DOI information using a single-layer scintillation crystal array with single-ended readout for cost-effective high-resolution positron emission tomography (PET). DOI information is estimated by different light dispersions along the x- and y-directions tailored by the geometric shape of reflectors around the crystals. The detector module comprised a 22 × 22 array of unpolished LGSO crystals (2.0 × 2.0 × 20 mm(3)). A multi-anode photomultiplier tube with 64 anodes measured light dispersion in the crystal array. Gain non-uniformity of each anode was corrected by an analogue gain compensation circuit. DOI information was determined from peaks in the x and y anode-signal distributions normalized by the total energy of the distribution. Average DOI resolution (full width at half maximum, FWHM) over all crystals and depths was estimated to be 4.2 mm. Average energy resolution from the 2 to 18 mm DOI positions was 11.3% ± 0.79%, with 13% difference in photo-peak positions. Average time resolutions (FWHM) were 320-356 ps. Energy, time and DOI resolutions were uniform over all crystal positions except at the array's edge. This DOI-PET detector shows promise for applications that require high resolution and sensitivity at low cost.
Collapse
Affiliation(s)
- Mikiko Ito
- Department of Nuclear Medicine, Seoul National University, Seoul 110-744, Korea
| | | | | |
Collapse
|
13
|
Schmall JP, Du J, Yang Y, Dokhale PA, McClish M, Christian J, Shah KS, Cherry SR. Comparison of large-area position-sensitive solid-state photomultipliers for small animal PET. Phys Med Biol 2012; 57:8119-34. [PMID: 23172720 DOI: 10.1088/0031-9155/57/24/8119] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This paper evaluates the performance of two large-area position-sensitive solid-state photomultipliers (PS-SSPM) for use in small animal PET detector designs. Both PS-SSPM device designs are 1 cm² in area, the first being a 2 × 2 tiled array of 5 mm × 5 mm PS-SSPMs and the second being a 10 mm × 10 mm continuous PS-SSPM. Signal-to-noise measurements were performed to investigate the optimal operating parameters for each device and to compare the performance of the two PS-SSPM designs. A maximum signal-to-noise ratio of 29.3 was measured for the 5 mm PS-SSPM array and 15.1 for the 10 mm PS-SSPM, both measurements were made at 0 °C and at the optimal bias voltage. The best energy resolution measured with an array of 1.3 mm polished LSO crystals was 16% for the 5 mm PS-SSPM array and 18% for the 10 mm PS-SSPM. The timing properties of both devices were similar, with a best timing resolution (in coincidence with an LSO/PMT detector) of 6.8 ns (range 6.8-8.9 ns) and 7.1 ns (range 7.1-9.6 ns) for the 5 mm PS-SSPM and 10 mm PS-SSPM respectively. The 2 × 2 array of 5 mm PS-SSPMs was able to visually resolve the elements in an 0.5 × 0.5 × 20 mm LYSO scintillator array (unpolished, diffuse reflector) with an average peak-to-valley ratio in the flood histograms of ∼11 indicating clear separation of the crystals. Advantages and drawbacks of PET detector designs using PS-SSPM photodetectors are addressed and comparisons to other small-animal PET detector designs using position-sensitive avalanche photodiodes are made.
Collapse
Affiliation(s)
- Jeffrey P Schmall
- Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, CA 95616, USA.
| | | | | | | | | | | | | | | |
Collapse
|