Geometry optimization of dual-layer offset detectors for compact ring diameter PET systems

Teimoorisichani, Mohammadreza; Goertzen, Andrew L.

doi:10.1109/nssmic.2016.8069606

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…The offset scintillator layer method is another type of configuration to acquire DOI information (Liu et al 2001, Zhang et al 2002. It differs from conventional phoswich configuration, for instance, the DOI information no longer depends on the decay-time difference, but on the light distribution (Ito et al 2011, Teimoorisichani andGoertzen 2017). This is done by shifting the top layer in the x and/or y direction relative to the bottom layer, so that a unique light distribution would correspond to each location in the phoswich detector (Liu et al 2001, Zhang et al 2002.…”

Section: Introductionmentioning

confidence: 99%

Wavelength discrimination (WLD) TOF-PET detector with DOI information

et al. 2020

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Depth-of-interaction (DOI) encoding can contribute to improving spatial resolution uniformity and sensitivity in positron-emission-tomography (PET) scanners. In addition, time-of-flight (TOF) PET scanners with DOI encoding have received considerable interest because of their potential for improving the spatial resolution, sensitivity, and image quality of the overall system. In this study, a new DOI detector configuration utilizing scintillators’ emission wavelength is proposed, and experimental results on the energy, timing, and DOI performance of the detector are provided. The DOI information from the proposed phoswich-type detector can be acquired at the detector level without complex signal processing by utilizing a single optical filter with customized optical properties. For this, we used either a short pass filter (SPF) or a long pass filter (LPF) that allows light photons of a specific wavelength to pass. The two-layered phoswich detector was configured with two scintillators with different photon-emission spectra. In this study, we used Ce:GAGG (3 mm × 3 mm × 10 mm) and LYSO:Ce (3 mm × 3 mm × 10 mm) as the top and bottom layer scintillators, respectively. A digital silicon photomultiplier (dSiPM) was used as the photosensor and for data acquisition. The phoswich detector was placed in the center of two dSiPM pixels, where one of the dSiPM pixels was covered with the optical filter, and the light guide was placed on the other pixel. The detector was tested for energy, timing, and DOI encoding performance. When an SPF was used, the energy resolutions of 16.2% and 11.8% were achieved for the Ce:GAGG (top layer) and LYSO:Ce (bottom layer) respectively without correcting for saturation effect. With a small (3 mm × 3 mm × 5 mm) LYSO crystal as the reference detector, CRTs (coincidence-resolving times) of 338 ps and 244 ps were recorded for the top and bottom layers respectively. The detector configuration also provides an excellent DOI-separation figure-of-merit (FoM) value of 1.9. In the case of LPF, the energy resolutions of 12.0% and 12.9% were achieved for the Ce:GAGG (top layer) and LYSO:Ce (bottom layer), respectively. CRTs (coincidence resolving times) of 314 ps and 263 ps were recorded for the top and bottom layers, respectively. The DOI-separation FoM value of 1.5 was achieved in this setup. Results show that the proposed method can provide excellent discrete DOI positioning accuracy without compromising the timing performance of the detector.

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Section: Introductionmentioning

confidence: 99%

Wavelength discrimination (WLD) TOF-PET detector with DOI information

et al. 2020

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“…The crystal width was assumed to be about 3 mm such that the adjacent block detectors in each detector ring just touch. Also, the front/back layer thickness (d F /d B ) for each total thickness d T was chosen according to a separate optimization study Goertzen 2016, Teimoorisichani andGoertzen 2018). Table 1 summarizes the geometrical properties of the DLO detectors considered in this study.…”

Section: Scanner Geometriesmentioning

confidence: 99%

A study of inter-crystal scatter in dual-layer offset scintillator arrays for brain-dedicated PET scanners

Teimoorisichani

Goertzen

2019

Phys. Med. Biol.

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A PET insert, mounted in a MR scanner, provides virtually all the advantages of a fully integrated PET/MR scanner. Various PET inserts have been proposed and built for small animal (Goertzen et al 2016, Ko et al 2016) and brain (Kolb et al 2012, Nishikido et al 2014, Jung et al 2015) hybrid PET/MR imaging. The limited diameter of an animal or organ-dedicated PET insert enhances the parallax error at large radial offsets which leads to a resolution loss in the scanner. Depth-of-interaction (DOI) detectors have been used to reduce the parallax error and maintain the resolution uniformity in small diameter PET scanners (

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“…While our previous work considered detectors of 10 to 30 mm thickness (Teimoorisichani and Goertzen 2016, in this work we considered detectors of 10, 15 and 20 mm thickness due to the limited bore diameter of the MR scanner and the sufficient estimated sensitivity achievable by a 20 mm thick detector. A total of 36 different detector areas between 0.04 (1 crystal per detector block) to 101.37 cm 2 (2500 crystals per detector block) were studied.…”

Section: Detector Geometrymentioning

confidence: 99%

“…There has been a significant interest in developing brain-dedicated positron emission tomography (PET) inserts and stand-alone scanners (Morimoto et al 2011, Yamamoto et al 2011, Kolb et al 2012, Mikhaylova et al 2014, Nishikido et al 2014, Jung et al 2015, 2016, Teimoorisichani and Goertzen 2016, Ahmed et al 2017. A braindedicated PET scanner requires a smaller bore diameter than a whole-body scanner which increases detection sensitivity while reducing the effects of photon acollinearity.…”

Section: Introductionmentioning

confidence: 99%

Count rate performance of brain-dedicated PET scanners: a Monte Carlo simulation study

Teimoorisichani

Goertzen

2019

Phys. Med. Biol.

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In recent years, there has been a renewed interest in brain-dedicated PET imaging systems, particularly in the context of combined PET/MR imaging. We are currently designing a brain-dedicated PET insert suitable for an ultra-high field brain-dedicated MR scanner, the Siemens Magnetom 7T MR scanner. In this paper, an investigation on the count rate performance of several possible detectors through a series of Monte Carlo simulations is reported. Brain-dedicated PET scanners with a lutetium oxyorthosilicate scintillator and a detector area of 0.04 (1 crystal per detector) to 101.37 (2500 crystals per detector) cm2, detector thickness of 10 to 20 mm and a fixed crystal pitch of ~2 mm were simulated. The count rate performance of each scanner was evaluated as a function of detector deadtime type and constant, coincidence timing window and lower level discriminator. Also, the effects of activity outside the field-of-view (FOV) on the count rate performance of each scanner were studied. For each detector geometry and performance metric, the scanner singles rate, scanner sensitivity and noise equivalent count rate as a function of activity in the FOV were measured. It was seen that scanners with detectors comprised a few crystal elements showed reduced scanner sensitivity due to a high number of inter-detector scattering. The count rate performance of scanners with large detectors, on the other hand, was mainly determined by the deadtime properties of the detectors. A model for the count rate performance of the scanner with each studied detector is presented in this work.

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Geometry optimization of dual-layer offset detectors for compact ring diameter PET systems

Cited by 5 publications

References 7 publications

Wavelength discrimination (WLD) TOF-PET detector with DOI information

Wavelength discrimination (WLD) TOF-PET detector with DOI information

A study of inter-crystal scatter in dual-layer offset scintillator arrays for brain-dedicated PET scanners

Count rate performance of brain-dedicated PET scanners: a Monte Carlo simulation study

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