Simulation study of a high‐performance brain <scp>PET</scp> system with dodecahedral geometry

Tao, Weijie; Chen, Gaoyu; Weng, Fenghua; Zan, Yunlong; Zhao, Zhixiang; Peng, Qiyu; Xu, Jianfeng; Huang, Qiu

doi:10.1002/mp.12996

Cited by 12 publications

(6 citation statements)

References 29 publications

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“…Furthermore, currently achievable timing resolution of ~200 ps is not sufficient to be helpful in small animal studies, therefore timing resolution is not prioritized. However, for human brain imaging, the scatter fraction is higher (Wienhard et al 2002, Kolb et al 2012, Tao et al 2018, and a narrow energy window is required to reconstruct high contrast images. The combination of a narrow energy window and poor energy resolution will reject many true events, thus degrading system sensitivity.…”

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confidence: 99%

Compton PET: a layered structure PET detector with high performance

Peng¹,

Judenhofer²,

Cherry³

2019

Phys. Med. Biol.

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In most high-resolution PET detector designs, there is an inherent trade-off between spatial resolution and detector efficiency. We have developed and tested a new geometry for the detector module which avoids this trade-off. The module uses a layered structure, in which four crystal slabs are stacked in the depth direction and optically separated by enhanced specular reflector (ESR) film. The scintillation light within each layer is measured by 16 SiPMs located on the four sides of the crystal. Analog signals from all SiPMs (4 × 16) on the four sides of the crystal are digitized individually using a 64-channel TOFPET-2 module. The four-sided readout method reduces the problem of light trapping resulting from total internal reflection when reading out the end(s) of traditional scintillation crystal arrays, thus increasing the light collection efficiency. In this work, we demonstrate the readout of a complete layered detector with 4 layers. The high light collection efficiency results in a FWHM energy resolution of 10.3%, and a FWHM timing resolution of 348 ps. The distribution of scintillation light detected by the SiPMs was used to decode the interaction position of each gamma ray using a trained neural network. A FWHM spatial resolution of 1.1 ± 0.1 mm was achieved. This design allows the detection efficiency of the module to be increased by adding additional crystal slabs along the depth direction. Since the position, energy, and timing are measured for each layer independently, increasing the system sensitivity by adding more layers will not affect the spatial/energy/timing resolution. Furthermore, the layered structure allows partial recovery of position information for events that undergo Compton scatter within the detector.

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confidence: 99%

Compton PET: a layered structure PET detector with high performance

Peng¹,

Judenhofer²,

Cherry³

2019

Phys. Med. Biol.

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“…This paper focuses on the design of PET scanners with the conventional geometry of cylindrical ring. Recently, many novel geometries, such as the hemispherical and dodecahedral geometries (Gong et al 2016, Tao et al 2018, have been proposed. However, those geometries are not the best candidates for the design of a light-weighted wearable brain PET without an external mechanic support system.…”

Section: Discussionmentioning

confidence: 99%

Design study of fully wearable high-performance brain PETs for neuroimaging in free movement

Tao¹,

Weng²,

Chen³

et al. 2020

Phys. Med. Biol.

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A practical wearable brain PET scanner capable of dynamic neuroimaging during free bodily movement will enable potential breakthrough basic neuroscience studies and help develop imaging-based neurological diagnoses and treatments. Weight, brain coverage, and sensitivity are three fundamental technical obstacles in the development of Fully Wearable High-Performance (FWHP) brain PET scanners. The purpose of this study is to investigate the feasibility of building a FWHP brain PET using a limited volume of lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystals. Six scanners, consisted of the same volume (2.66 kg) of LYSO scintillators with combinations of 2 different crystal pitches (3 mm and 1.5 mm) and 3 different crystal lengths (20 mm, 10 mm, and 5 mm), were simulated. The performances of the six scanners were assessed and compared with Siemen's HRRT brain PET and mCT whole-body PET, in terms of aperture, axial field of views (AFOV), sensitivity, spatial resolution, count rates, and image noise property. The time-of-flight (TOF) information was included in the image reconstruction to improve the effective sensitivity. The effects of the TOF was assessed by scanning a Jaszczak phantom and reconstructing images with the maximum likelihood expectation maximization (MLEM) algorithm with different timing settings (non-TOF, 500 ps, 200 ps, 100 ps and 50 ps Coincidence Time Resolution, CTR). The signal-noise ratio (SNR) of the images were assessed and compared with those of the HRRT scanner and mCT scanner. The results show that it is possible to construct a FWHP brain PET with better spatial resolution than the dedicated HRRT brain PET, comparable effective sensitivity (with 50 ~100 ps CTR), and whole-brain coverage (23.7 cm inner diameter and 13.4 cm axial field of view) using 2.66 kg of LYSO.

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“…Most of the DOI detectors were developed to reduce the parallax errors in preclinical scanners and organ-specific scanners (such as brain scanners 25,45 ) with small diameters. The crystal sizes of the DOI detectors for small animal imaging are usually <2 mm.…”

Section: Discussionmentioning

confidence: 99%

A depth encoding PET detector using four‐crystals‐to‐one‐SiPM coupling and light‐sharing window method

et al. 2019

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Purpose Depth of interaction (DOI) decoding capability is of great importance for positron emission tomography (PET) requiring high resolution. In this study, we presented a novel low‐cost DOI detector design with four crystals coupling to one SiPM, based on the method of rectangular light‐sharing window (RLSW). A prototype detector was constructed, calibrated, and assessed using the methods of homogeneous radiation and flood map analysis. Methods The DOI detector was constructed with a 4 × 4 array of lutetium‐yttrium oxyorthosilicate (LYSO) crystals (2.95 mm × 2.95 mm × 20 mm3), barium sulfate (BaSO4) reflectors, and optical glues. A RLSW 7 mm in height was deployed in the BaSO4 reflectors. A non‐DOI detector with identical dimensions and without RLSW was also constructed for comparison. The light‐output surface of the detector was air‐coupled with a 4 × 4 array of SiPMs (3 mm × 3 mm2). The signals generated from the 16 SiPMs were read out by a custom‐designed electronic system, and the signals from four adjacent 3 mm SiPMs were summed into one signal to emulate a 2 × 2 array of 6 mm SiPMs. The RLSW caused the DOI‐related position shifts of the crystal spots in the flood map. A homogeneous radiation method was used to establish the transfer functions to convert the spot shifts measured from the flood map into DOI measurements. The accuracy of the DOI measurements was assessed with data acquired using the conventional collimated radiation method. Results All 16 crystals are distinctly separated from each other in the flood map. Twelve crystals, including four central crystals and eight edge crystals, have the DOI capability. The full width half maximum (FWHM) of the DOI measurements of the central crystals and the edge crystals are 3.06 ± 0.08 and 3.79 ± 0.15 mm, respectively, for the configuration with four crystals coupling to one SiPM. By contrast, the FWHMs (3.98 ± 0.16 and 5.12 ± 0.38 mm, respectively) are slightly worse for the configuration with one crystal coupling to one SiPM. The average and standard deviation (STD) of the FWHM energy resolutions of the DOI detector and non‐DOI detector were 10.2% ± 0.7% and 10.7% ± 1.7%, respectively. Their FWHM coincidence timing resolutions were 197.0 ± 9.6 and 206.4 ± 13.3 ps, respectively. The RLSW had no significant impact on the energy resolutions and timing resolutions of the DOI detector. Conclusions The novel four‐crystals‐to‐one‐SiPM coupling technology is a cost‐efficient approach to construct high‐performance detector modules with DOI capability. The methods of homogeneous radiation and flood map analysis are easy to perform and of good performance. Those methods can be adapted in the clinic PET scanners to enable the capability of DOI measurements.

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Simulation study of a high‐performance brain PET system with dodecahedral geometry

Abstract: In conclusion, the proposed dodecahedral PET system is potential for widespread applications in high-sensitivity, high-resolution PET imaging, to lower the injected dose.

Cited by 12 publications

References 29 publications

Compton PET: a layered structure PET detector with high performance

Compton PET: a layered structure PET detector with high performance

Design study of fully wearable high-performance brain PETs for neuroimaging in free movement

A depth encoding PET detector using four‐crystals‐to‐one‐SiPM coupling and light‐sharing window method

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