Instrumentation for Time-of-Flight Positron Emission Tomography

Ullah, Muhammad Nasir; Pratiwi, Eva; Cheon, Jimin; Choi, Hojong; Yeom, Jung Yeol

doi:10.1007/s13139-016-0401-5

Cited by 28 publications

(22 citation statements)

References 117 publications

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“…However, in recent years SiPM detectors emerged as a new technology foreseen as a promising alternative to PMTs [ 11 ]. These photodetectors offer several advantages including relative indifference to the magnetic fields of MR which made them attractive for the use in hybrid PET/MR systems, compact size, and potentially low production costs [ 11 , 12 ]. Furthermore, SiPM are characterized by excellent intrinsic time resolution and high photon-detection efficiency, which made them the most favorable devices to be coupled with TOF reconstruction [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality

et al. 2018

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BackgroundA newly introduced PET/CT scanner (Discovery Meaningful Insights—DMI, GE Healthcare) includes the silicon photomultiplier (SiPM) with time-of-flight (TOF) technology first used in the GE SIGNA PET/MRI. In this study, we investigated the impact of various acquisition times on image quality using this SiPM-based PET/CT.MethodsWe reviewed data from 58 participants with cancer who were scanned using the DMI PET/CT scanner. The administered dosages ranged 295.3–429.9 MBq (mean ± SD 356.3 ± 37.4) and imaging started at 71–142 min (mean ± SD 101.41 ± 17.52) after administration of the radiopharmaceutical. The patients’ BMI ranged 19.79–46.16 (mean ± SD 26.55 ± 5.53). We retrospectively reconstructed the raw TOF data at 30, 60, 90, and 120 s/bed and at the standard image acquisition time per clinical protocol (180 or 210 s/bed depending on BMI). Each reconstruction was reviewed blindly by two nuclear medicine physicians and scored 1–5 (1—poor, 5—excellent quality). The liver signal-to-noise ratio (SNR) was used as a quantitative measure of image quality.ResultsThe average scores ± SD of the readers were 2.61 ± 0.83, 3.70 ± 0.92, 4.36 ± 0.82, 4.82 ± 0.39, and 4.91 ± 0.91 for the 30, 60, 90, and 120 s/bed and at standard acquisition time, respectively. Inter-reader agreement on image quality assessment was good, with a weighted kappa of 0.80 (95% CI 0.72–0.81). In the evaluation of the effects of time per bed acquisition on semi-quantitative measurements, we found that the only time point significantly different from the standard time were 30 and 60 s (both with P < 0.001). The effects of dose and BMI were not statistically significant (P = 0.195 and 0.098, respectively). There was a significant positive effect of time on SNR (P < 0.001), as well as a significant negative effect of weight (P < 0.001).ConclusionsOur results suggest that despite significant delays from injection to imaging (due to comparison with standard PET/CT) compared to standard clinical operations and even in a population with average BMI > 25, images can be acquired as fast as 90 s/bed using the SiPM PET/CT and still result in very good image quality (average score > 4).

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Section: Introductionmentioning

confidence: 99%

Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality

et al. 2018

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“…Improvements in PET instrumentation over the years include the use of fast lutetium oxyorthosilicate crystals permitting shorter coincidence timing windows (4,5), new reconstruction methods with time-of-flight (TOF) application (5)(6)(7)(8)(9) for improved image signal-to-noise ratio, and expansion of the axial field of view for increased volume sensitivity and axial coverage (9). Recently, silicon photomultiplier (SiPM)-based detectors emerged, offering several advantages over photomultiplier tubes such as more compact size, higher intrinsic time resolution, and higher photondetection efficiency, making them favorable for coupling with TOF reconstruction (10,11).…”

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confidence: 99%

Image Quality and Semiquantitative Measurements on the Biograph Vision PET/CT System: Initial Experiences and Comparison with the Biograph mCT

et al. 2019

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In May 2018, the Biograph Vision PET/CT system was installed at the University Medical Center Groningen. This study evaluated the initial experiences with this new PET/CT system in terms of perceived image quality and semiquantitative analysis in comparison to the Biograph mCT as a reference. Methods: In total, 20 oncologic patients were enrolled and received a single 3 MBq/kg injected dose of 18 F-FDG followed by a dual-imaging PET scan. Ten patients were scanned on the Biograph mCT first, whereas the other 10 patients were scanned on the Biograph Vision first. The locally preferred clinically reconstructed images were blindly reviewed by 3 nuclear medicine physicians and scored (using a Likert scale of 1-5) on tumor lesion demarcation, overall image quality, and image noise. In addition, these clinically reconstructed images were used for semiquantitative analysis by measurement of SUVs in tumor lesions. Images acquired using reconstructions conform with the European Association of Nuclear Medicine Research Ltd. (EARL) specifications were also used for measurements of SUV in tumor lesions and healthy tissues for comparison between systems. Results: The 18 F-FDG dose received by the 14 men and 6 women (age range, 36-84; mean ± SD, 61 ± 16 y) ranged from 145 to 405 MBq (mean ± SD, 268 ± 59.3). Images acquired on the Biograph Vision were scored significantly higher on tumor lesion demarcation, overall image quality, and image noise than images acquired on the Biograph mCT (P , 0.001). The overall interreader agreement showed a Fleiss κ of 0.61 (95% confidence interval, 0.53-0.70). Furthermore, the SUVs in tumor lesions and healthy tissues agreed well (within 95%) between PET/CT systems, particularly when EARL-compliant reconstructions were used on both systems. Conclusion: In this initial study, the Biograph Vision showed improved image quality compared with the Biograph mCT in terms of lesion demarcation, overall image quality, and visually assessed signal-to-noise ratio. The 2 systems are comparable in semiquantitatively assessed image biomarkers in both healthy tissues and tumor lesions. Improved quantitative performance may, however, be feasible using the clinically optimized reconstruction settings.

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“…Precise CRT allows time-of-flight (TOF) PET that reduces scan times (Surti 2015, Ullah et al 2016 and injected doses (Surti andKarp 2015, Son et al 2016). The per-crystal CRTs were measured as a function of the overvoltage, as shown in figure 13.…”

Section: Crtmentioning

confidence: 99%

Delay grid multiplexing: simple time-based multiplexing and readout method for silicon photomultipliers

Won

Lee

2016

Phys. Med. Biol.

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In this paper, we propose a fully time-based multiplexing and readout method that uses the principle of the global positioning system. Time-based multiplexing allows simplifying the multiplexing circuits where the only innate traces that connect the signal pins of the silicon photomultiplier (SiPM) channels to the readout channels are used as the multiplexing circuit. Every SiPM channel is connected to the delay grid that consists of the traces on a printed circuit board, and the inherent transit times from each SiPM channel to the readout channels encode the position information uniquely. Thus, the position of each SiPM can be identified using the time difference of arrival (TDOA) measurements. The proposed multiplexing can also allow simplification of the readout circuit using the time-to-digital converter (TDC) implemented in a field-programmable gate array (FPGA), where the time-over-threshold (ToT) is used to extract the energy information after multiplexing. In order to verify the proposed multiplexing method, we built a positron emission tomography (PET) detector that consisted of an array of 4 × 4 LGSO crystals, each with a dimension of 3 × 3 × 20 mm, and one- to-one coupled SiPM channels. We first employed the waveform sampler as an initial study, and then replaced the waveform sampler with an FPGA-TDC to further simplify the readout circuits. The 16 crystals were clearly resolved using only the time information obtained from the four readout channels. The coincidence resolving times (CRTs) were 382 and 406 ps FWHM when using the waveform sampler and the FPGA-TDC, respectively. The proposed simple multiplexing and readout methods can be useful for time-of-flight (TOF) PET scanners.

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Instrumentation for Time-of-Flight Positron Emission Tomography

Cited by 28 publications

References 117 publications

Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality

Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality

Image Quality and Semiquantitative Measurements on the Biograph Vision PET/CT System: Initial Experiences and Comparison with the Biograph mCT

Delay grid multiplexing: simple time-based multiplexing and readout method for silicon photomultipliers

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