A Four-Layer DOI Detector With a Relative Offset for Use in an Animal PET System

Ito, Mikiko; Lee, Jae Sung; Kwon, Sun Il; Lee, Geon Song; Hong, B.; Lee, Kyong Sei; Sim, K. S.; Lee, Seok Jae; Rhee, J.T.; Hong, S. J.

doi:10.1109/tns.2010.2044892

Cited by 72 publications

(57 citation statements)

References 19 publications

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“…Several groups have shown that depth-ofinteraction encoding with SiPM is feasible (13). Implementing the depth-of-interaction encoding methods suggested by our group (14,16,32) will also be possible using the SiPM arrays.…”

Section: Discussionmentioning

confidence: 97%

“…The dead space between the sensitive areas of SiPMs was 2 mm between each column of the SiPM array and 1 mm between each row. Each crystal, with a dimension of 1.5 · 1.5 · 7.0 mm, was optically separated using a grid of an enhanced spectral reflector polymer (3M) with a 0.065-mm thickness (14,16). The pitch between the crystals was 1.65 mm on average, resulting in a packing fraction of 85% for a detector module.…”

Section: Detector Modulementioning

confidence: 99%

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Development of Small-Animal PET Prototype Using Silicon Photomultiplier (SiPM): Initial Results of Phantom and Animal Imaging Studies

Kwon¹,

Lee²,

Yoon³

et al. 2011

J Nucl Med

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Silicon photomultiplier (SiPM; also called a Geiger-mode avalanche photodiode) is a promising semiconductor photosensor in PET and PET/MRI because it is intrinsically MRI-compatible and has internal gain and timing properties comparable to those of a photomultiplier tube. In this study, we have developed a smallanimal PET system using SiPMs and lutetium gadolinium oxyorthosilicate (LGSO) crystals and performed physical evaluation and animal imaging studies to show the feasibility of this system. Methods: The SiPM PET system consists of 8 detectors, each of which comprises 2 · 6 SiPMs and 4 · 13 LGSO crystals. Each crystal has dimensions of 1.5 · 1.5 · 7 mm. The crystal face-toface diameter and axial field of view are 6.0 cm and 6.5 mm, respectively. Bias voltage is applied to each SiPM using a finely controlled voltage supply because the gain of the SiPM strongly depends on the supply voltage. The physical characteristics were studied by measuring energy resolution, sensitivity, and spatial resolution. Various mouse and rat images were obtained to study the feasibility of the SiPM PET system in in vivo animal studies. Reconstructed PET images using a maximum-likelihood expectation maximization algorithm were coregistered with animal CT images. Results: All individual LGSO crystals within the detectors were clearly distinguishable in flood images obtained by irradiating the detector using a 22 Na point source. The energy resolution for individual crystals was 25.8% 6 2.6% on average for 511-keV photopeaks. The spatial resolution measured with the 22 Na point source in a warm background was 1.0 mm (2 mm off-center) and 1.4 mm (16 mm off-center) when the maximum-likelihood expectation maximization algorithm was applied. A myocardial 18 F-FDG study in mice and a skeletal 18 F study in rats demonstrated the fine spatial resolution of the scanner. The feasibility of the SiPM PET system was also confirmed in the tumor images of mice using 18 F-FDG and 68 Ga-RGD and in the brain images of rats using 18 F-FDG. Conclusion: These results indicate that it is possible to develop a PET system using a promising semiconductor photosensor, which yielded reasonable PET performance in phantom and animal studies.

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Section: Discussionmentioning

confidence: 97%

Section: Detector Modulementioning

confidence: 99%

Development of Small-Animal PET Prototype Using Silicon Photomultiplier (SiPM): Initial Results of Phantom and Animal Imaging Studies

Kwon¹,

Lee²,

Yoon³

et al. 2011

J Nucl Med

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“…Most DOI detectors employ light sharing over several photosensors, utilize crystals with varied decay time constant, or deliberately alter light collection/wavelength along a scintillator crystal. [21][22][23][24][25][26][27][28][29] This, inevitably, in most cases slows the rise-time and reduces signal-to-noise ratio of the detector signal, compromising timing performance. 15 It is therefore, extremely challenging to fabricate a high performance TOF detector that also provides fine DOI resolution.…”

Section: Background and Theorymentioning

confidence: 99%

Side readout of long scintillation crystal elements with digital SiPM for TOF‐DOI PET

2014

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Purpose: Side readout of scintillation light from crystal elements in positron emission tomography (PET) is an alternative to conventional end-readout configurations, with the benefit of being able to provide accurate depth-of-interaction (DOI) information and good energy resolution while achieving excellent timing resolution required for time-of-flight PET. This paper explores different readout geometries of scintillation crystal elements with the goal of achieving a detector that simultaneously achieves excellent timing resolution, energy resolution, spatial resolution, and photon sensitivity. Methods: The performance of discrete LYSO scintillation elements of different lengths read out from the end/side with digital silicon photomultipliers (dSiPMs) has been assessed. Results: Compared to 3 × 3 × 20 mm 3 LYSO crystals read out from their ends with a coincidence resolving time (CRT) of 162 ± 6 ps FWHM and saturated energy spectra, a side-readout configuration achieved an excellent CRT of 144 ± 2 ps FWHM after correcting for timing skews within the dSiPM and an energy resolution of 11.8% ± 0.2% without requiring energy saturation correction. Using a maximum likelihood estimation method on individual dSiPM pixel response that corresponds to different 511 keV photon interaction positions, the DOI resolution of this 3 × 3 × 20 mm 3 crystal side-readout configuration was computed to be 0.8 mm FWHM with negligible artifacts at the crystal ends. On the other hand, with smaller 3 × 3 × 5 mm 3 LYSO crystals that can also be tiled/stacked to provide DOI information, a timing resolution of 134 ± 6 ps was attained but produced highly saturated energy spectra. Conclusions: The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable outstanding detector performance in terms of timing, energy, and DOI resolution. C 2014 American Association of Physicists in Medicine. [http://dx

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“…high light yield, stopping power, and short decay time). We performed timing measurements on the R9800 using a 4 × 4 × 10 mm 3 LYSO crystal whose properties were almost the same as those of the LSO and found it to have excellent performance in our previous investigations [10,11]. The crystal size used in this study (having a large cross section and short length) allowed the timing resolution to not be affected by the geometry of crystal.…”

Section: Fast Pmts and Lysomentioning

confidence: 90%

Evaluation of a fast photomultiplier tube for time-of-flight PET

2011

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Purpose Adding time-of-flight (TOF) information to positron emission tomography (PET) can lead to an improvement in image quality because TOF information allows the estimation of gamma ray annihilation positions in three dimensions. For accurate position estimation, precise time resolution is the most important characteristic required of TOF-PET detectors. The aims of this study were to establish the optimal setup for timing measurements and to evaluate the timing performance of a fast photomultiplier tube (PMT) (Hamamatsu R9800) coupled with a lutetium yttrium orthosilicate (LYSO) scintillation crystal for TOF-PET detector development. Methods Performance of a fast PMT (diameter, 25 mm; length, 55 mm) coupled with a LYSO crystal (4 × 4 × 10 mm 3 ) was measured in coincidence experiments with 511 keV annihilation photons from a 22 Na gamma source. Timing measurement optimization was carried out with a leadingedge discriminator (LED) and a constant fraction discriminator (CFD). Results Results showed the optimal timing resolution could be obtained with a CFD time delay of 1 ns; timing resolutions (FWHM) of the LYSO crystal-coupled fast PMT were measured to be 198 and 254 ps for two different R9800PMTs. The energy resolutions at 511 keV were 10.8% and 10.6%, respectively. Additional experiments to determine the position uncertainty were performed at three different source positions and the position uncertainty (FWHM) in the TOF measurement using these PMTs was estimated to be 4.50 cm. Conclusions The performance of fast R9800 PMT coupled with a LYSO crystal showed good potential for development as a TOF-PET detector module.

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A Four-Layer DOI Detector With a Relative Offset for Use in an Animal PET System

Cited by 72 publications

References 19 publications

Development of Small-Animal PET Prototype Using Silicon Photomultiplier (SiPM): Initial Results of Phantom and Animal Imaging Studies

Development of Small-Animal PET Prototype Using Silicon Photomultiplier (SiPM): Initial Results of Phantom and Animal Imaging Studies

Side readout of long scintillation crystal elements with digital SiPM for TOF‐DOI PET

Evaluation of a fast photomultiplier tube for time-of-flight PET

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