NEMA NU4-2008 Performance Evaluation of Albira: A Two-Ring Small-Animal PET System Using Continuous LYSO Crystals

Pajak, Malgorzata; Völgyes, David; Pimlott, Sally L.; Salvador, Carlos C.; Asensi, Antonio S.; McKeown, Clare; Waldeck, Jens; Anderson, Kurt I.

doi:10.2174/1874220301603010012

Cited by 9 publications

(11 citation statements)

References 18 publications

(21 reference statements)

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“…The Bruker Albira is a multipurpose preclinical PET scanner equipped with monolithic crystals and multi-anode photomultiplier tubes. The achieved radial and axial spatial resolutions were 1.72 and 2.45 mm, respectively, whereas the maximum absolute sensitivity was 5.3% [5]. The MOLECUBES β-CUBE is a commercial small-animal PET scanner that was designed using a monolithic Lutetium-Yttrium Oxyorthosilicate doped with Cerium (LYSO: Ce) crystal with 8 mm thickness attached to 3 mm × 3 mm Silicon photomultipliers.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…DOI information reduce the parallax error at off-center positions within a PET ring (radial astigmatism) [17], especially important for preclinical or organ-dedicated applications [18]. While preclinical scanners based on DOI-capable monolithic detectors are already available [19], [20], most current wholebody scanner employ segmented detector designs without DOI [21]. One of the main challenges to widely translate monolithic scintillators to both preclinical and clinical application are efficient calibration routines and positioning algorithms.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Simulation of an Adaptable Fan-Beam Collimator for Fast Calibration of Radiation Detectors for PET

Hetzel

Mueller

Grahe

et al. 2020

IEEE Trans. Radiat. Plasma Med. Sci.

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Monolithic scintillators for positron emission tomography systems perform best when calibrated individually. We present a fan-beam collimator with which a crystal can be calibrated within less than 1 h when suitable positioning algorithms are applied. The collimator is manufactured from lead, features an easily adaptable slit to tune the beam width and can be operated together with a coincidence detector to select a clean sample of 511-keV annihilation photons. We evaluated the performance of the collimator with a Geant4 simulation for slit widths of 0.25 mm, 0.4 mm, and 1 mm and validated the shape of the beam profile experimentally by step-wisely moving a detector into the beam. This shows a clear narrow and box-shaped beam profile even if the collimator is operated without the coincidence setup. In the latter configuration, the fraction of gammas in the beam region on a 50×50 mm 2 large detector is between 48% and 79% which is improved significantly to more than 94% by using only coincidence events. Analyzing the energy distribution shows that the fraction of 511-keV photons is increased from less than 50% to more than 96% by selecting coincidences.

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“…However, the sensitivity can still be greatly improved by reducing the gaps/dead space between scintillator elements and detector modules (St James et al 2010 and González-Montoro et al 2017). PET detectors based on monolithic crystals, which eliminate the dead space caused by the reflectors in scintillator arrays, have been successfully used for preclinical PET and are under evaluation for clinical PET (Pajak et al 2016 and Mikhaylova et al 2017). However, the readout electronics and position estimation algorithms are more complicated and require very careful calibration compared to PET detectors based on scintillator arrays, which typically use simple center of gravity algorithms to estimate the gamma photon interaction position (Joung et al 2002, Wang et al 2011 and Du et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Shared-photodetector readout to improve the sensitivity of positron emission tomography

Peng

Bai

et al. 2018

Phys. Med. Biol.

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Sensitivity is an important performance characteristic of positron emission tomography (PET) systems. Improved sensitivity can be used to reduce injected dose, reduce scan time, or improve the signal-to-noise ratio and temporal resolution for dynamic studies. One way to improve the sensitivity of PET scanners is to reduce the gaps between detector modules. In this paper, a new signal processing method, named the shared-photodetector readout method, is proposed and evaluated. In this method, the signals generated in nearest neighbor photodetectors adjacent to the detector module of interest, were used to help identify the interaction location in the detector module of interest. Using this method, scintillator array-based detector modules with almost 100% packing fraction can be built, and the edge crystals can be clearly resolved, even when the crystals are small compared to the photodetector size. To evaluate this signal processing concept in one dimension, a detector block with four dual-ended readout detector modules, was designed. The detector block consisted of eight 4 × 4 arrays of SensL MicroFJ-30035 SiPMs coupled to both ends of a 14 × 56 array of 0.9 × 0.9 × 20 mm LYSO elements with a pitch size of 0.96 mm and a length of 20 mm. Performance in terms of energy resolution, flood histogram, timing resolution and depth-of-interaction resolution obtained using the shared-photodetector readout method were compared to those obtained using a conventional readout method. The results show that better over-all performance was achieved using the shared-photodetector readout method, especially at the edges and corners of the array.

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NEMA NU4-2008 Performance Evaluation of Albira: A Two-Ring Small-Animal PET System Using Continuous LYSO Crystals

Cited by 9 publications

References 18 publications

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

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

Characterization and Simulation of an Adaptable Fan-Beam Collimator for Fast Calibration of Radiation Detectors for PET

Shared-photodetector readout to improve the sensitivity of positron emission tomography

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