Time of flight measurements based on FPGA and SiPMs for PET–MR

Aguilar, Albert; Garcia-Olcina, R.; Martínez, P.A.; Martos, Julio; Soret, J.; Torres, J.; Benlloch, J.; González, Antonio J.; Sánchez, F.

doi:10.1016/j.nima.2013.09.008

Cited by 9 publications

(11 citation statements)

References 12 publications

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“…xc7k325t-2ffg900). The TDC was tested previously and a time resolution below 80 ps FWHM was obtained for a pair of channels [14]. Different pulses coming from the detector stage were introduced on each FPGA-TDC channel.…”

Section: B Tdcmentioning

confidence: 99%

“…As it has been studied by the authors in other publications such as [14] or [29], a breakeven point has to be encountered to accomplish two premises: a sufficiently low threshold value in order to take advantage of the first arrival photons (best time performance) but high enough to avoid the electronic noise, which is present in such a low level signal amplitude. The results of such a scan are shown in Fig.…”

Section: A Scenariomentioning

confidence: 99%

“…Furthermore, SiPMs present better quantum efficiency, i.e., the number of impact photons that generate an electrical current is higher (50% compared to 25% in the case of most PMTs). Parameters that limit time resolution such as transit time spread (time jitter) are improved in SiPMs, making their use feasible for TOF measurements [12]- [14]. Moreover, they are able to work in magnetic fields whereas PMTs are highly sensitive to such environments.…”

mentioning

confidence: 99%

“…In the second case, a CRT of 2.1 ns was achieved with a reference low-jitter detector and a matrix of SiPM detector pairs. Although several tests have been successfully performed by the authors with single SiPMs coupled to individual Teflon wrapped crystal pixels [14], the combination of multiple SiPMs is not an easy task since they present a range of gains and optimum voltages that can significantly vary from one to another. In this paper, CRT studies with arrays of SiPMs and an active area of mm mm each, were successfully carried out.…”

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confidence: 99%

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Timing Results Using an FPGA-Based TDC with Large Arrays of 144 SiPMs

Aguilar

González

Torres

et al. 2015

IEEE Trans. Nucl. Sci.

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Section: B Tdcmentioning

confidence: 99%

Section: A Scenariomentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Timing Results Using an FPGA-Based TDC with Large Arrays of 144 SiPMs

Aguilar

González

Torres

et al. 2015

IEEE Trans. Nucl. Sci.

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“…By coupling lutetium oxyorthosilicate crystals with new SiPM technology, a timing resolution sufficient for time-of-flight PET measurements has already been reached (9). The considerably lower noise of SiPMs than of avalanche photodiodes and the high gain (;10 6 ) are additional features making this technology promising for PET photodetectors in high magnetic fields.…”

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confidence: 99%

A Promising Future: Comparable Imaging Capability of MRI-Compatible Silicon Photomultiplier and Conventional Photosensor Preclinical PET Systems

et al. 2015

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We recently completed construction of a small-animal PET systemthe MiniPET-3-that uses state-of-the-art silicon photomultiplier (SiPM) photosensors, making possible dual-modality imaging with MRI. In this article, we compare the MiniPET-3 with the MiniPET-2, a system with the same crystal geometry but conventional photomultiplier tubes (PMTs). Methods: The standard measurements proposed by the National Electrical Manufacturers Association NU 4 protocols were performed on both systems. These measurements included spatial resolution, system sensitivity, energy resolution, counting rate performance, scatter fraction, spillover ratio for air and water, recovery coefficient, and image uniformity. The energy windows were set to 350-650 keV on the MiniPET-2 and 360-662 keV on the MiniPET-3. Results: Spatial resolution was approximately 17% better on average for the MiniPET-3 than the MiniPET-2. The systems performed similarly in terms of peak absolute sensitivity (∼1.37%), spillover ratio for air (∼0.15), spillover ratio for water (∼0.25), and recovery coefficient (∼0.33, 0.59, 0.81, 0.89, and 0.94). Uniformity was 5.59% for the MiniPET-2 and 6.49% for the MiniPET-3. Minor differences were found in scatter fraction. With the ratlike phantom, the peak noise-equivalent counting rate was 14 kcps on the MiniPET-2 but 24 kcps on the MiniPET-3. However, with the mouselike phantom, these values were 55 and 91 kcps, respectively. The optimal coincidence time window was 6 ns for the MiniPET-2 and 8 ns for the MiniPET-3. Conclusion: Images obtained with the SiPM-based Mini-PET-3 small-animal PET system are similar in quality to those obtained with the conventional PMT-based MiniPET-2.Key Words: MiniPET; small-animal PET scanner; performance evaluation; instrumentation; molecular imaging J Nucl Med 2015; 56:1948 56: -1953 56: DOI: 10.2967 Ef forts to integrate PET and MRI have advanced significantly in recent years, fostered mainly by new photosensor technologies (1-4). Conventional photomultiplier tube (PMT) detectors benefit from high signal gain in the range of 10 5 -10 7 (5,6). Low noise and fast transit time (;100 ps) are also available today and have made PMTs the first candidate for applications involving time-of-flight PET technology. In addition, PMTs have lower noise than avalanche photodiode or silicon photomultiplier (SiPM) detectors (5). However, in strong magnetic fields PMTs cannot produce position maps that are acceptable for imaging purposes. In contrast, avalanche photodiodes can be used efficiently as a photosensor for PET when near strong magnets. Some successful approaches using avalanche photodiodes have already been introduced for combined PET/MRI applications (2,7,8). However, avalanche photodiodes have significantly higher rise times than PMTs (up to 2-3 ns) (5), preventing the timing resolution from being adequate for time-of-flight PET. The low gain (;10 2 ) is also a disadvantage of avalanche photodiodes (2,5).By coupling lutetium oxyorthosilicate crystals with new SiPM technology, a timing resolutio...

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