Depth of Interaction and Coincidence Time Resolution Characterization of Ultrahigh Resolution Time-of-Flight Prism-PET Modules

Cao, Xinjie; Bella, Andy La; Zeng, Xinjie; Zhao, Wei; Goldan, Amir H.

doi:10.1109/trpms.2021.3110902

Cited by 16 publications

(14 citation statements)

References 33 publications

(44 reference statements)

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“…Recently, we have developed a novel depth-encoding single-ended readout PET detector module that utilizes a segmented prismatoid light-guide array, hence the name Prism-PET, for enhanced and localized light sharing. [28][29][30][31] The Prism-PET detectors have achieved unsurpassed spatial, DOI, and TOF resolutions when compared to other single-ended readout PET detector technologies. 32,33 In this study, we have developed a one-ring prototype TOF-DOI Prism-PET brain scanner using a compact and conformal decagon geometry.…”

Section: Introductionmentioning

confidence: 99%

A conformal TOF–DOI Prism‐PET prototype scanner for high‐resolution quantitative neuroimaging

et al. 2023

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Background: Positron emission tomography (PET) has had a transformative impact on oncological and neurological applications. However, still much of PET's potential remains untapped with limitations primarily driven by low spatial resolution, which severely hampers accurate quantitative PET imaging via the partial volume effect (PVE). Purpose: We present experimental results of a practical and cost-effective ultra-high resolution brain-dedicated PET scanner, using our depth-encoding Prism-PET detectors arranged along a compact and conformal gantry, showing substantial reduction in PVE and accurate radiotracer uptake quantification in small regions. Methods: The decagon-shaped prototype scanner has a long diameter of 38.5 cm, a short diameter of 29.1 cm, and an axial field-of -view (FOV) of 25.5 mm with a single ring of 40 Prism-PET detector modules. Each module comprises a 16 × 16 array of 1.5 × 1.5 × 20-mm 3 lutetium yttrium oxyorthosillicate (LYSO) scintillator crystals coupled 4-to-1 to an 8 × 8 array of silicon photomultiplier (SiPM) pixels on one end and to a prismatoid light guide array on the opposite end. The scanner's performance was evaluated by measuring depth-of -interaction (DOI) resolution, energy resolution, timing resolution, spatial resolution, sensitivity, and image quality of ultra-micro Derenzo and three-dimensional (3D) Hoffman brain phantoms. Results:The full width at half maximum (FWHM) DOI, energy, and timing resolutions of the scanner are 2.85 mm, 12.6%, and 271 ps, respectively. Not considering artifacts due to mechanical misalignment of detector blocks, the intrinsic spatial resolution is 0.89-mm FWHM. Point source images reconstructed with 3D filtered back-projection (FBP) show an average spatial resolution of 1.53-mm FWHM across the entire FOV. The peak absolute sensitivity is 1.2% for an energy window of 400−650 keV. The ultra-micro Derenzo phantom study demonstrates the highest reported spatial resolution performance for a human brain PET scanner with perfect reconstruction of 1.00-mm diameter hot-rods. Reconstructed images of customized Hoffman brain phantoms prove that Prism-PET enables accurate radiotracer uptake quantification in small brain regions (2-3 mm).Xinjie Zeng and Zipai Wang contributed equally to this study.

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Section: Introductionmentioning

confidence: 99%

A conformal TOF–DOI Prism‐PET prototype scanner for high‐resolution quantitative neuroimaging

et al. 2023

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“…The ground truth DOI was calculated based on the distance from the hit position to the surface of the corresponding crystal. In order to accurately simulate the DOI performance of the Prism‐PET detector modules, Gaussian noise with 4 and 2 mm full width at half maximum (FWHM) was added to the ground truth DOI of the Prism‐PET 1 mm and 1.5 mm scanners, respectively 65,68,69 …”

Section: Methodsmentioning

confidence: 99%

“…In order to accurately simulate the DOI performance of the Prism-PET detector modules, Gaussian noise with 4 and 2 mm full width at half maximum (FWHM) was added to the ground truth DOI of the Prism-PET 1 mm and 1.5 mm scanners, respectively. 65,68,69 A virtual cylindrical scanner (VC) with 0.5 × 0.5 mm 2 virtual crystals was modeled, shown as the yellow ring in Figure 2. Each list-mode event was rebinned to a pair of VC crystals along the same line of response (LOR).…”

Section: Spatial Resolutionmentioning

confidence: 99%

“…64 In this paper, we introduce our cost-effective, highresolution, and high-sensitivity conformal brain PET scanner using our patented Prism-PET detector technology. [65][66][67][68][69][70][71][72] Prism-PET detector blocks utilize segmented prismatoid light-guide array for localized and enhanced light sharing and their salient features are: 4-to-1 and 9-to-1 coupling of scintillator crystals to readout pixels, 65,66 single-ended depth encoding readout with sub-2-mm depth-of -interaction (DOI) resolution, 69 improved time-of -flight (TOF) performance using DOI corrections, 67,68 and accurate decomposition of multi-crystal events for Compton scatter recovery (Ref. 70 and supplementary section in Ref.…”

Section: Introductionmentioning

confidence: 99%

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High‐resolution and high‐sensitivity PET for quantitative molecular imaging of the monoaminergic nuclei: A GATE simulation study

et al. 2022

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Purpose Quantitative in vivo molecular imaging of fine brain structures requires high‐spatial resolution and high‐sensitivity. Positron emission tomography (PET) is an attractive candidate to introduce molecular imaging into standard clinical care due to its highly targeted and versatile imaging capabilities based on the radiotracer being used. However, PET suffers from relatively poor spatial resolution compared to other clinical imaging modalities, which limits its ability to accurately quantify radiotracer uptake in brain regions and nuclei smaller than 3 mm in diameter. Here we introduce a new practical and cost‐effective high‐resolution and high‐sensitivity brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detector modules arranged in a conformal decagon geometry, to substantially reduce the partial volume effect and enable accurate radiotracer uptake quantification in small subcortical nuclei. Methods Two Prism‐PET brain scanner setups were proposed based on our 4‐to‐1 and 9‐to‐1 coupling of scintillators to readout pixels using 1.5×1.5×20$1.5 \times 1.5 \times 20$ mm3 and 0.987×0.987×20$0.987 \times 0.987 \times 20$ mm3 crystal columns, respectively. Monte Carlo simulations of our Prism‐PET scanners, Siemens Biograph Vision, and United Imaging EXPLORER were performed using Geant4 application for tomographic emission (GATE). National Electrical Manufacturers Association (NEMA) standard was followed for the evaluation of spatial resolution, sensitivity, and count‐rate performance. An ultra‐micro hot spot phantom was simulated for assessing image quality. A modified Zubal brain phantom was utilized for radiotracer imaging simulations of 5‐HT1A receptors, which are abundant in the raphe nuclei (RN), and norepinephrine transporters, which are highly concentrated in the bilateral locus coeruleus (LC). Results The Prism‐PET brain scanner with 1.5 mm crystals is superior to that with 1 mm crystals as the former offers better depth‐of‐interaction (DOI) resolution, which is key to realizing compact and conformal PET scanner geometries. We achieved uniform 1.3 mm full‐width‐at‐half‐maximum (FWHM) spatial resolutions across the entire transaxial field‐of‐view (FOV), a NEMA sensitivity of 52.1 kcps/MBq, and a peak noise equivalent count rate (NECR) of 957.8 kcps at 25.2 kBq/mL using 450–650 keV energy window. Hot spot phantom results demonstrate that our scanner can resolve regions as small as 1.35 mm in diameter at both center and 10 cm away from the center of the transaixal FOV. Both 5‐HT1A receptor and norepinephrine transporter brain simulations prove that our Prism‐PET scanner enables accurate quantification of radiotracer uptake in small brain regions, with a 1.8‐fold and 2.6‐fold improvement in the dorsal RN as well as a 3.2‐fold and 4.4‐fold improvement in the bilateral LC compared to the Biograph Vision and EXPLORER, respectively. Conclusions Based on our simulation results, the proposed high‐resolution and high‐sensitivity Prism‐PET brain scanner is a promising cost‐effective candidate ...

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“…However, the light is mostly redirected back to the primary crystal, resulting in suboptimal DOI. Recently, a segmented prism light guide design named Prism-PET is used to determine intercrystal light sharing and enhances DOI resolution [38], [39], [40], [41], [42] Monolithic crystals are also used for DOI measurement with single-ended readout design [43], in which the spread of scintillation light from the interaction position in a single and continuous crystal is used to estimate the plane coordinate and DOI position [44]. Despite the appealing high sensitivity and DOI capability, the monolithic crystals suffer the edge effects that may seriously affect the DOI measurement accuracy [45].…”

Section: Introductionmentioning

confidence: 99%

Single-Ended Readout Depth-of-Interaction Measurements Based on Random Forest Algorithm

Cheng

Wang

et al. 2023

IEEE Trans. Radiat. Plasma Med. Sci.

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The depth-of-interaction (DOI) information can reduce parallax errors and improve the spatial resolution of positron emission tomography (PET) imaging. Current DOI detectors, with either single-ended readout design or dual-ended readout design, usually require substantial changes to the crystal arrays and/or readout electronics. In this work, we proposed a single-ended readout DOI estimation approach with minimal changes in the detector hardware design, using a supervised machine learning algorithm, random forest (RF). The energy value measured from one end of the crystal, combined with sample points of the pulse signal, were used as inputs to the DOI estimation algorithm, which provided a DOI performance close to that of the dual-ended readout design. We compared the proposed single-ended RF method with the classic dual-ended energy ratio method and a dual-ended version of the RF method, using positioning error and resolution as performance metrics for DOI estimation. All three methods achieved average absolute DOI positioning errors of <1.00 mm and average DOI resolutions of <2.20 mm full width at half maximum (FWHM). More specifically, we achieved the averaged DOI resolutions of 2.15, 1.80, and 1.93 mm FWHM for the single-ended RF method, dual-ended RF method, and dual-ended energy ratio method, respectively. In conclusion, the single-ended RF method achieved comparable performance without extra photodetectors and readout electronics and may provide a feasible solution for DOI estimation.

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Depth of Interaction and Coincidence Time Resolution Characterization of Ultrahigh Resolution Time-of-Flight Prism-PET Modules

Cited by 16 publications

References 33 publications

A conformal TOF–DOI Prism‐PET prototype scanner for high‐resolution quantitative neuroimaging

A conformal TOF–DOI Prism‐PET prototype scanner for high‐resolution quantitative neuroimaging

High‐resolution and high‐sensitivity PET for quantitative molecular imaging of the monoaminergic nuclei: A GATE simulation study

Single-Ended Readout Depth-of-Interaction Measurements Based on Random Forest Algorithm

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