Sensitivity improvement of time-of-flight (ToF)-PET detector through recovery of Compton scattered annihilation photons

Wagadarikar, Ashwin A.; Iván, Adrián; Dolinsky, S.; McDaniel, David L.

doi:10.1109/nssmic.2012.6551725

Cited by 9 publications

(8 citation statements)

References 2 publications

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“…In terms of validating the GATE MC simulations, the simulated NEMA sensitivity values, presented in Tables 1 , 3 , were in line with the expected, theoretical values for all simulated PET radioisotopes, These theoretical values were based on the measured GE Signa PET/MR sensitivity for 18 F while accounting for the differences in branching ratio between each isotope and 18 F. These sensitivity values confirmed the higher count rate and increased sensitivity ( Iagaru et al, 2019 ) of the GE Signa PET system due several design factors including Compton scatter recovery, longer axial FOV and reduced ring diameter ( Lubberink and Herzog, 2011 ; Wagadarikar et al, 2014 ; Hsu et al, 2017 ).…”

Section: Discussionsupporting

confidence: 81%

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

et al. 2020

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NEMA characterization of PET systems is generally based on 18 F because it is the most relevant radioisotope for the clinical use of PET. 18 F has a half-life of 109.7 min and decays into stable 18 O via β+ emission with a probability of over 96% and a maximum positron energy of 0.633 MeV. Other commercially available PET radioisotopes, such as 82 Rb and 68 Ga have more complex decay schemes with a variety of prompt gammas, which can directly fall into the energy window and induce false coincidence detections by the PET scanner. Methods: Aim of this work was threefold: (A) Develop a GATE model of the GE Signa PET/MR to perform realistic and relevant Monte Carlo simulations (B) Validate this model with published sensitivity and Noise Equivalent Count Rate (NECR) data for 18 F and 68 Ga (C) Use the validated GATE-model to predict the system performance for other PET isotopes including 11 C, 15 O, 13 N, 82 Rb, and 68 Ga and to evaluate the effect of a 3T magnetic field on the positron range. Results: Simulated sensitivity and NECR tests performed with the GATE-model for different radioisotopes were in line with literature values. Simulated sensitivities for 18 F and 68 Ga were 21.2 and 19.0 /kBq, respectively, for the center position and 21.1 and 19.0 cps/kBq, respectively, for the 10 cm off-center position compared to the corresponding measured values of 21.8 and 20.0 cps/kBq for the center position and 21.1 and 19.6 cps/kBq for the 10 cm off-center position. In terms of NECR, the simulated peak NECR was 216.8 kcps at 17.40 kBq/ml for 18 F and 207.1 kcps at 20.10 kBq/ml for 68 Ga compared to the measured peak NECR of 216.8 kcps at 18.60 kBq/ml and 205.6 kcps at 20.40 kBq/ml for 18 F and 68 Ga, respectively. For 11 C, 13 N, and 15 O, results confirmed a peak NECR similar to 18 F with the effective activity concentration scaled by the inverse of the positron fraction. For 82 Rb, and 68 Ga, the peak NECR was lower than for 18 F while the corresponding activity concentrations were higher. For the higher energy positron emitters, the positron range was confirmed to be

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Section: Discussionsupporting

confidence: 81%

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

et al. 2020

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“…This design also reduces the amount of PET-attenuating material in the PET field of view, contributing in part to the reduced activity requirements. The use of scatter recovery techniques additionally supports this advantage as well [ 25 ].…”

Section: Discussionmentioning

confidence: 98%

“…A recent study has evaluated the advantage of the implementation of such recovery procedures by using the inter-block Compton scatter on TOF-PET scanners. It was found that this setup is expected to result in an overall scanner sensitivity improvement of up to 20% without significant processing overhead [ 25 ].…”

Section: Discussionmentioning

confidence: 99%

Dose Optimization in TOF-PET/MR Compared to TOF-PET/CT

Queiroz

Delso²,

Wollenweber³

et al. 2015

PLoS ONE

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PurposeTo evaluate the possible activity reduction in FDG-imaging in a Time-of-Flight (TOF) PET/MR, based on cross-evaluation of patient-based NECR (noise equivalent count rate) measurements in PET/CT, cross referencing with phantom-based NECR curves as well as initial evaluation of TOF-PET/MR with reduced activity.Materials and MethodsA total of 75 consecutive patients were evaluated in this study. PET/CT imaging was performed on a PET/CT (time-of-flight (TOF) Discovery D 690 PET/CT). Initial PET/MR imaging was performed on a newly available simultaneous TOF-PET/MR (Signa PET/MR). An optimal NECR for diagnostic purposes was defined in clinical patients (NECRP) in PET/CT. Subsequent optimal activity concentration at the acquisition time ([A]0) and target NECR (NECRT) were obtained. These data were used to predict the theoretical FDG activity requirement of the new TOF-PET/MR system. Twenty-five initial patients were acquired with (retrospectively reconstructed) different imaging times equivalent for different activities on the simultaneous PET/MR for the evaluation of clinically realistic FDG-activities.ResultsThe obtained values for NECRP, [A]0 and NECRT were 114.6 (± 14.2) kcps (Kilocounts per second), 4.0 (± 0.7) kBq/mL and 45 kcps, respectively. Evaluating the NECRT together with the phantom curve of the TOF-PET/MR device, the theoretical optimal activity concentration was found to be approximately 1.3 kBq/mL, which represents 35% of the activity concentration required by the TOF-PET/CT. Initial evaluation on patients in the simultaneous TOF-PET/MR shows clinically realistic activities of 1.8 kBq/mL, which represent 44% of the required activity.ConclusionThe new TOF-PET/MR device requires significantly less activity to generate PET-images with good-to-excellent image quality, due to improvements in detector geometry and detector technologies. The theoretically achievable dose reduction accounts for up to 65% but cannot be fully translated into clinical routine based on the coils within the FOV and MR-sequences applied at the same time. The clinically realistic reduction in activity is slightly more than 50%. Further studies in a larger number of patients are needed to confirm our findings.

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“…Recovering triple coincidences has been proposed as another approach for sensitivity increase . Typically in PET imaging, a pair of 511‐keV annihilation photons are coincidently detected and a (LOR) is drawn.…”

Section: Introductionmentioning

confidence: 99%

“…Second, we compared different recovery schemes that are expected to be efficient for small ‐ animal PET geometry and relatively simple for real implementation . An accurate recovery scheme has to be applied to correctly find the true LORs of the IDS events . Finally, the effects of the PET system properties, including energy resolution and DOI capabilities on the performance of IDS recovery methods were explored.…”

Section: Introductionmentioning

confidence: 99%

Systematic study on factors influencing the performance of interdetector scatter recovery in small‐animal PET

Lee

Kim

et al. 2018

Medical Physics

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As a fundamental research for real implementation of IDS recovery, we conducted a simulation study to evaluate the factors affecting sensitivity increase, recovery accuracy, and image quality. Sensitivity increase was dependent on the energy window and energy resolution, while the recovery accuracy was affected by energy window, recovery scheme, energy resolution, and DOI capability. In image quality analysis, sensitivity increase and recovery accuracy dominantly affected the noise and quantitative accuracy, respectively. Among the recovery schemes, the proportional scheme obtained the best image quality.

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Sensitivity improvement of time-of-flight (ToF)-PET detector through recovery of Compton scattered annihilation photons

Cited by 9 publications

References 2 publications

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

Dose Optimization in TOF-PET/MR Compared to TOF-PET/CT

Systematic study on factors influencing the performance of interdetector scatter recovery in small‐animal PET

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