Concept Verification of Three-Layer DOI Detectors for Small Animal PET

Hong, S. J.; Kwon, Sun Il; Ito, Mikiko; Lee, Geon Song; Sim, K. S.; Park, Kwang Suk; Rhee, J.T.; Lee, Jae Sung

doi:10.1109/tns.2008.920258

Cited by 33 publications

(30 citation statements)

References 22 publications

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“…We chose LGSO because it has a fast scintillation decay time (t 5 41 ns), good stopping power (m 5 0.85 cm 21 at 511 keV), and high light output. It has yielded outstanding performance in our previous investigations (18,20), and its MRI compatibility was confirmed (21). The LGSO array consists of 360 (20 · 18) crystals (Supplemental Fig.…”

Section: Pet Detector Modulementioning

confidence: 84%

Initial Results of Simultaneous PET/MRI Experiments with an MRI-Compatible Silicon Photomultiplier PET Scanner

Yoon¹,

Ko²,

Kwon³

et al. 2012

J Nucl Med

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165

102

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The most investigated semiconductor photosensor for MRIcompatible PET detectors is the avalanche photodiode (APD). However, the silicon photomultiplier (SiPM), also called the Geiger-mode APD, is gaining attention in the development of the next generation of PET/MRI systems because the SiPM has much better performance than the APD. We have developed an MRI-compatible PET system based on multichannel SiPM arrays to allow simultaneous PET/MRI. Methods: The SiPM PET scanner consists of 12 detector modules with a ring diameter of 13.6 cm and an axial extent of 3.2 cm. In each detector module, 4 multichannel SiPM arrays (with 4 · 4 channels arranged in a 2 · 2 array to yield 8 · 8 channels) were coupled with 20 · 18 Lu 1.9 Gd 0.1 SiO 5 :Ce crystals (each crystal is 1.5 · 1.5 · 7 mm) and mounted on a charge division network for multiplexing 64 signals into 4 position signals. Each detector module was enclosed in a shielding box to reduce interference between the PET and MRI scanners, and the temperature inside the box was monitored for correction of the temperature-dependent gain variation of the SiPM. The PET detector signal was routed to the outside of the MRI room and processed with a field programmable gate array-based data acquisition system. MRI compatibility tests and simultaneous PET/MRI acquisitions were performed inside a 3-T clinical MRI system with 4-cm loop receiver coils that were built into the SiPM PET scanner. Interference between the imaging systems was investigated, and phantom and mouse experiments were performed. Results: No radiofrequency interference on the PET signal or degradation in the energy spectrum and flood map was shown during simultaneous PET/MRI. The quality of the MRI scans acquired with and without the operating PET showed only slight degradation. The results of phantom and mouse experiments confirmed the feasibility of this system for simultaneous PET/MRI. Conclusion: Simultaneous PET/MRI was possible with a multichannel SiPM-based PET scanner, with no radiofrequency interference on PET signals or images and only slight degradation of the MRI scans. A hybrid PET/MRI scanner has many potential advantages, including a reduced radiation dose, better soft-tissue contrast on MRI than CT, an almost unlimited combination of functional and molecular information, and possible motion correction of the PET image using MRI data (1-4). However, simultaneous PET/MRI with a conventional photomultiplier tube (PMT)-based PET camera is technically challenging, because the PMT is highly sensitive to the magnetic field. Almost every property of the PMT PET signal is distorted within the magnetic field. For example, the energy spectrum of the PET detector is quite diminished because of the loss of PMT signal output, and the peak position of the scintillation crystal cannot be distinguished in the flood maps of block detectors (1). Therefore, if relatively long optical fiber bundles are not used, the PMT PET camera should be placed a distance from the MRI machine (5). Consequently, a longer scan time is...

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Section: Pet Detector Modulementioning

confidence: 84%

Initial Results of Simultaneous PET/MRI Experiments with an MRI-Compatible Silicon Photomultiplier PET Scanner

Yoon¹,

Ko²,

Kwon³

et al. 2012

J Nucl Med

Self Cite

165

102

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“…In the LabPET scanner, the PET component of the Triumph pre-clinical SPECT/PET/CT system produced by GE, LYSO and LGSO crystals coupled to APD detectors are employed, and digital signals are sampled using fast free-running ADC and analyzed using an adaptive filtering scheme to discriminate the interaction position [55]. In addition, to the abovementioned commercialized scanners, the feasibility of the pulse shape discrimination method has been confirmed by several other research groups [56,57].…”

Section: Discrete Doi Encodingmentioning

confidence: 96%

“…DOI information can be also obtained using light emitted from the rear surfaces of stacked, optically coupled, multiple crystal blocks [52][53][54][55][56][57]. This method offers cost advantages over the above-mentioned direct readout from crystal layers method, because no additional photo-sensors are required.…”

Section: Discrete Doi Encodingmentioning

confidence: 99%

“…19D). Hong et al demonstrated the feasibility of combining the relative offset method and the pulse shape discrimination method for 3 or 4-layer DOI detectors [57]. Eight-layer DOI detectors could be also devised by combining the 4 layer encoding method, the relative offset or jPET method, and the pulse shape discrimination method [63].…”

Section: Discrete Doi Encodingmentioning

confidence: 99%

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Technical Advances in Current PET and Hybrid Imaging Systems

Lee¹

2010

TONMEDJ

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Abstract:The continuing efforts of investigators to achieve the best physical and clinical performances from PET (positron emission tomography) and related hybrid cameras (PET/CT and PET/MRI) have led to remarkable technical advances in hardware and software.Time of flight (TOF) information measurement, which has been enabled thanks to the invention of fast, heavy crystals and advances in fast light detection sensors and readout electronics, is used to obtain the PET images of better quality and lesion-detection performance. Statistical reconstruction with resolution recovery and measurements of depth of interaction (DOI) are the useful software-and hardware-wise approaches for enhancing the spatial resolution of reconstructed PET images. These technical advances along with an expansive increase in the number of PET and PET/CT examinations performed are facilitating the widespread use of PET scanners with specific detector structures and arrangements for particular applications or organs. Combined multimodal imaging systems are also in the development mainstream of these PET systems.In this paper, these important technologies (TOF measurements, statistical reconstruction with resolution recovery, DOI detectors, and application-specific PET cameras) that have made major contributions to advances in state-of-the-art clinical and preclinical PET and hybrid systems are reviewed.

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“…To achieve this, several methods to obtain depth of interaction (DOI) information have been proposed [2][3][4][5][6]. In our previous study [7], we demonstrated the feasibility of three-layer depth of interaction (DOI) detectors for a small animal PET using the Monte-Carlo simulation. In this system, three-level DOI encoding was possible due to the relative offset between crystals by one-half a crystal pitch in the x-and y-directions, along with different decay times.…”

Section: Introductionmentioning

confidence: 99%