Development and preliminary results of Xtrim-PET, a modular cost-effective preclinical scanner

Sajedi, Salar; Zeraatkar, Navid; Taheri, Mohsen; Kaviani, Sanaz; Khanmohammadi, Hadi; Sarkar, Saeed; Sabet, Hamid; Ay, Mohammad Reza

doi:10.1016/j.nima.2019.06.009

Cited by 7 publications

(7 citation statements)

References 26 publications

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“…The PET models implemented in GEANT4 and the image reconstruction code were validated against the empirical data obtained from a prototype small animal PET scanner designed and fabricated in our lab (Amirrashedi et al 2019, Sajedi et al 2019. The details of the validation procedures are described in our previous study (Sanaat et al 2019).…”

Section: Validation and Performance Evaluationmentioning

confidence: 99%

Novel preclinical PET geometrical concept using a monolithic scintillator crystal offering concurrent enhancement in spatial resolution and detection sensitivity: a simulation study

Sanaat

Arabi

et al. 2020

Phys. Med. Biol.

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We propose a small-animal PET scanner design combining two sets of monolithic crystals with two different thicknesses. The detectors with thinner crystals serve for high resolution imaging while the thicker crystals retain the detection efficiency. Two small-animal PET models based on 10 and 12 detector blocks made of monolithic LYSO crystals were implemented in the GEANT4 Monte Carlo toolkit. In each of these models, half of the detector blocks consisted of a crystal thickness of 10 mm whereas the second half had a crystal thickness of 2 mm. The scintillator crystals were coupled to SiPM arrays. For the first model, the detector blocks were arranged in a full-ring polygonal geometry in such a way that detector blocks with the same thickness were sitting opposite to each other. For the second model, detector blocks with different crystal thicknesses were facing each other. The performance of the proposed PET models was assessed using standard parameters, including spatial resolution, sensitivity and noise equivalent count rate. Comparison was made with conventional PET models with crystal thicknesses of 2 mm, 6 mm and 10 mm. PET models with a crystal thickness of 2 mm led to the highest spatial resolution (up to 0.6 mm FWHM) at the cost of poor absolute sensitivity (2.5%). On the other hand, PET models with a crystal thickness of 10 mm led to good detection efficiency (4.4%), yet with substantial degradation of spatial resolution (1.2 mm FWHM). The proposed PET models with thick and thin crystals exhibited an optimal trade-off between spatial resolution and sensitivity outperforming the PET model with fixed 6 mm crystal by achieving a spatial resolution of 0.7 mm and absolute sensitivity of 3.7%. The novel proposed PET design concept achieved an optimal trade-off between the sensitivity and spatial resolution by combining two sets of monolithic crystals.

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Section: Validation and Performance Evaluationmentioning

confidence: 99%

Novel preclinical PET geometrical concept using a monolithic scintillator crystal offering concurrent enhancement in spatial resolution and detection sensitivity: a simulation study

Sanaat

Arabi

et al. 2020

Phys. Med. Biol.

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“…For the coincidence filter, the raw data collected in list mode should be sorted based on the time stamp. Since the amount of raw data for the uniformity calibration was more than 600 GB, we implemented 12 stages of the fast swapping technique presented in [36] for fast sorting of raw data in the coincidence filter. Based on this method, we have also implemented a delayed coincidence filter for correcting random coincidences.…”

Section: Coincidence Filtermentioning

confidence: 99%

Limited-angle TOF-PET for intraoperative surgical applications: proof of concept and first experimental data

et al. 2022

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The intraoperative gamma probe (IPG) based on single gamma-ray detection remains the current gold standard modality for sentinel lymph node identification and tumor removal in cancer patients. However, IPGs do not meet the <5% false negative rate (FNR) requirement, a key metric suggested by the American Society of Clinical Oncology (ASCO). We aim to reduce FNR by using time of flight (TOF) PET detector technology in limited angle geometry system by using only two detector panels in coincidence. For proof of concept, we used two Hamamatsu TOF PET detector modules (C13500-4075YC-12) featuring 12× 12 arrays of 4.14× 4.14× 20 mm3 LFS crystal pixels with 4.2 mm pitch and coupled one-one to silicon photomultiplier (SiPM) pixels. The measured detector coincidence timing resolution (CTR) was 271 ps FWHM for the whole detector. We 3D printed lesion phantom containing spheres 2–10 mm in diameter, representing lymph nodes, and placed it inside a 10-liter warm background water phantom. Experimental results showed that with subminute data acquisition, 6 mm diameter spheres could be identified in the image when a lesion phantom with a 10:1 activity ratio to background was used. The simulation results were in good agreement with the experimental data by resolving 6 mm diameter spherical lesions with a 60 second acquisition time in a 25 cm deep background water phantom with a 10:1 activity ratio. As expected, the image quality improved as the CTR improved in the simulation and with decreasing background water phantom depth or increasing lesion-to-background activity ratio in the experiment. With the results presented here, we concluded that using a limited angle TOF PET detector system is a major step forward for intraoperative applications in that lesion detectability is beyond what conventional gamma- and NIR-based probes could achieve.

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“…To assess the potential of machine learning in event positioning, two small-animal PET scanners were simulated with two different positioning approaches (conventional Anger login and MLP). For further experimental validation, the number of detector modules and geometrical configuration were similar to the Xtrim preclinical PET scanner recently designed and developed in our lab [14,15].…”

Section: Geometrical Configuration Of Preclinical Pet Scannermentioning

confidence: 99%

Depth of Interaction Estimation in a Preclinical PET Scanner Equipped with Monolithic Crystals Coupled to SiPMs Using a Deep Neural Network

Sanaat

Zaidi

2020

Applied Sciences

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The scintillation light distribution produced by photodetectors in positron emission tomography (PET) provides the depth of interaction (DOI) information required for high-resolution imaging. The goal of positioning techniques is to reverse the photodetector signal’s pattern map to the coordinates of the incident photon energy position. By considering the DOI information, monolithic crystals offer good spatial, energy, and timing resolution along with high sensitivity. In this work, a supervised deep neural network was used for the approximation of DOI and to assess through Monte Carlo (MC) simulations the performance on a small-animal PET scanner consisting of ten 50 × 50 × 10 mm3 continuous Lutetium-Yttrium Oxyorthosilicate doped with Cerium (LYSO: Ce) crystals and 12 × 12 silicon photomultiplier (SiPM) arrays. The scintillation position was predicted by a multilayer perceptron neural network with 256 units and 4 layers whose inputs were the number of fired pixels on the SiPM plane and the total deposited energy. A GEANT4 MC code was used to generate training and test datasets by altering the photons’ incident position, energy, and direction, as well as readout of the photodetector output. The calculated spatial resolutions in the X-Y plane and along the Z-axis were 0.96 and 1.02 mm, respectively. Our results demonstrated that using a multilayer perceptron (MLP)-based positioning algorithm in the detector modules, constituting the PET scanner, enhances the spatial resolution by approximately 18% while the absolute sensitivity remains constant. The proposed algorithm proved its ability to predict the DOI for depth under 7 mm with an error below 8.7%.

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Development and preliminary results of Xtrim-PET, a modular cost-effective preclinical scanner

Cited by 7 publications

References 26 publications

Novel preclinical PET geometrical concept using a monolithic scintillator crystal offering concurrent enhancement in spatial resolution and detection sensitivity: a simulation study

Novel preclinical PET geometrical concept using a monolithic scintillator crystal offering concurrent enhancement in spatial resolution and detection sensitivity: a simulation study

Limited-angle TOF-PET for intraoperative surgical applications: proof of concept and first experimental data

Depth of Interaction Estimation in a Preclinical PET Scanner Equipped with Monolithic Crystals Coupled to SiPMs Using a Deep Neural Network

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