Evaluation of Geiger-mode APDs for PET block detector designs

Kolb, Armin; Lorenz, E.; Judenhofer, Martin S.; Renker, D.; Lankes, Konrad; Pichler, Bernd J.

doi:10.1088/0031-9155/55/7/003

Cited by 74 publications

(54 citation statements)

References 37 publications

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“…This technological advance may have paved the way for even more sophisticated PET detectors based on so-called Geiger mode avalanche photodiodes (G-APDs), which are currently under evaluation [28] and might be ideal candidates for future PET detectors, enabling the construction of a low-cost system with TOF imaging capability. The evaluation of the new detector generation based on APDs yielded a spatial resolution of less than 3 mm in the central FOV, a coincident time resolution of 4.9 ns, an excellent point source sensitivity of approximately 7.8 % and good overall image quality.…”

Section: Discussionmentioning

confidence: 99%

Technical performance evaluation of a human brain PET/MRI system

et al. 2012

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Section: Discussionmentioning

confidence: 99%

Technical performance evaluation of a human brain PET/MRI system

et al. 2012

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“…14,15 The next generation of APDs are known as Geiger mode avalanche photodiodes (G-APDs) and are promising candidates for replacing both PMTs and APDs, especially in multimodality imaging devices where space is limited or magnetic fields are applied. [18][19][20][21] G-APDs reach a gain comparable to PMTs, of the order of 10 6 , and provide a timing performance in connection with a fast scintillator in the picosecond range. 22 As a consequence, PET/MR imaging devices based on G-APDs have been developed.…”

Section: Introductionmentioning

confidence: 99%

Development of a novel depth of interaction PET detector using highly multiplexed G‐APD cross‐strip encoding

Kolb¹,

Parl²,

Mantlik³

et al. 2014

Medical Physics

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Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25 μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated 18 F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 ± 0.15 mm. Conclusions: The novel DoI PET detector, which is based on strip G-APD arrays, yielded a DoI resolution of 2.9 mm and excellent timing and energy resolution. Its high multiplexing factor reduces the number of electronic channels. Thus, this cross-strip approach enables low-cost, high-performance PET detectors for dedicated small animal PET and PET/MRI and potentially clinical PET/MRI systems.

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“…The temperature-dependent gain variation of Circled regions are where signal-to-noise ratio, summarized in Table 4, was estimated. MPPC is about 5% per degree at room temperature (17,28). In this study, we used the gain compensation method in which the ADC output is scaled retrospectively using the temperature information measured continuously during PET/MRI data acquisition.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, the silicon photomultiplier (SiPM)-also called the Geiger-mode APD, solid-state photomultiplier, multipixel photon counter (MPPC)-is gaining much attention as a promising photosensor for future PET/MRI systems, because it is insensitive to the magnetic field and has amplification gain and timing resolution equivalent to those of the PMT (10)(11)(12). Therefore, several groups, including us, have worked on the development of SiPM PET detectors and systems (13)(14)(15)(16)(17)(18)(19).…”

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

Yoon¹,

Ko²,

Kwon³

et al. 2012

J Nucl Med

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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Evaluation of Geiger-mode APDs for PET block detector designs

Cited by 74 publications

References 37 publications

Technical performance evaluation of a human brain PET/MRI system

Technical performance evaluation of a human brain PET/MRI system

Development of a novel depth of interaction PET detector using highly multiplexed G‐APD cross‐strip encoding

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

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