Connections Between Noise Equivalent Count Rate and Image Noise in Pet Medical Imaging

Antić, Vojislav; Haglund, Julie

doi:10.21175/radproc.2016.44

Cited by 1 publication

(1 citation statement)

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“…3A) is the most relevant parameter for characterizing the count rate performance. In short, it describes the true coincidence count rate that would be needed in an idealcase scenario (without random and scatter events) to obtain the same SNR as in a real-case scenario for a given activity concentration (28). In other words, the SNR can be improved by using a higher injected activity up to the point where peak NEC rate is reached.…”

Section: Count Rate Performancementioning

confidence: 99%

Performance Evaluation of the Vereos PET/CT System According to the NEMA NU2-2012 Standard

et al. 2018

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The aim of this study was to evaluate the physical performance of the Vereos whole-body PET/CT system according to the National Electrical Manufacturers Association (NEMA) NU2-2012 standard and to compare it with other state-of-the-art PET/CT systems. Methods: Spatial resolution, sensitivity, count-rate performance, count rate accuracy, and image quality were assessed. Specifically, spatial resolution was measured using an 18 F point-source. System sensitivity was calculated from acquisitions of an 18 F line source inside aluminum tubes of varying thickness. Assessment of count rate performance and count rate accuracy was based on measurements of an 18 F line source inside a 20-cm-diameter polyethylene cylinder. PET image quality was assessed using a NEMA IQ phantom. All measurements were performed according to the predefined and implemented NEMA NU2-2012 acquisition protocols at a clinical installation of a Vereos PET/CT system. Evaluation was performed using the software provided by the vendor. Results: The average (radial and tangential) transverse spatial resolution was 4.2, 4.5, and 5.5 mm in full width at half maximum for a 1-, 10-, and 20-cm radial offset, respectively, from the center of the field of view. Axial spatial resolution varied between 4.2 and 4.6 mm in full width at half maximum, depending on the radial source position. The average sensitivity was 5.2 cps/kBq. A peak noise-equivalent count (NEC) rate of 153.4 kcps was measured at an activity concentration of 54.9 kBq/mL. The scatter fraction at peak NEC rate was 33.9%, and the maximum count rate error at and below peak NEC rate was 6.8%. Contrast recovery coefficients varied from 54.3% (10-mm sphere) to 83.9% (22-mm sphere) for the hot spheres, and between 81.4% (28-mm sphere) and 87% (37-mm sphere) for the cold spheres for a given sphere-to-background ratio of 4:1. Conclusion: The overall performance characteristics of the Vereos PET/CT system are comparable to state-of-the-art wholebody PET/CT systems with the exception that the peak NEC rate occurs at a higher activity concentration, thus indicating the ability of the Vereos PET/CT system to cover a wider range of activities.

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Section: Count Rate Performancementioning

confidence: 99%