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Mini EXPLORER II: a prototype high-sensitivity PET/CT scanner for companion animal whole body and human brain scanning
摘要： As part of the EXPLORER total-body positron emission tomography (PET) project, we have designed and built a high-resolution, high-sensitivity PET/CT scanner which is expected to have excellent performance for companion animal whole body and human brain imaging. The PET component has a ring diameter of 52 cm and an axial field of view of 48.3 cm. The detector modules are composed of arrays of lutetium (yttrium) oxyorthosilicate (LYSO) crystals of dimensions 2.76x2.76x18.1 mm coupled to silicon photomultipliers (SiPMs) for read-out. The CT component is a 24 detector row CT scanner with a 50 kW X-ray tube. PET system time-of-flight resolution was measured to be 409±39 ps and average system energy resolution was 11.7%±1.5% at 511 keV. The NEMA NU2-2012 system sensitivity was found to be 52-54 kcps/MBq. Spatial resolution was 2.6 mm at 10mm from the center of the FOV and 2.0 mm rods were clearly resolved on a mini-Derenzo phantom. Peak noise-equivalent count (NEC) rate, using the NEMA NU 2-2012 phantom, was measured to be 314 kcps at 9.2 kBq/cc. The CT scanner passed the technical components of the American College of Radiology (ACR) accreditation tests. We have also performed scans of a Hoffman brain phantom and we show images from the first canine patient imaged on this device.
关键词： NEMA,PET/CT,EXPLORER,total-body PET,companion animal,brain
更新于2025-09-23 15:23:52
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Performance characteristics of the digital Biograph Vision PET/CT system
摘要： This study evaluates the performance of the Siemens Biograph Vision digital PET/CT system (Siemens Healthineers, Knoxville, USA) according to the NEMA NU 2‐2012 standard (published by the National Electrical Manufacturers Association (NEMA)) to allow for a reliable, reproducible, and inter‐system comparable performance measurement. Methods: The new digital PET/CT features silicon photomultiplier (SiPM)‐based detectors with 3.2 mm lutetium oxyorthosilicate (LSO) crystals and full coverage of the scintillator area. The PET components incorporate eight rings of 38 detector blocks and each block contains 4x2 mini‐blocks. Each mini‐block consists of a 5x5 LSO‐array of 3.2x3.2x20 mm crystals coupled to a SiPM‐array of 16x16 mm, resulting in an axial field of view (FOV) of 26.1 cm. In this study PET/CT system performance will be evaluated conform the NEMA NU 2‐2012 standard with additional measurements described in the new NEMA NU 2‐2018 standard. Spatial resolution, sensitivity, count‐rate performance, accuracy of attenuation and scatter correction, Time‐of‐Flight (TOF) performance, and image quality will be determined. Measurements will be directly compared to results from its predecessor, the Biograph mCT Flow, using existing literature. Moreover, feasibility to comply with the European Association of Nuclear Medicine (EANM) Research Ltd (EARL) criteria will be evaluated and some illustrative patient PET images will be shown. Results: The Biograph Vision shows a transverse (resp. axial) spatial resolution at Full Width Half Maximum (FWHM) of 3.6 mm (resp. 3.5 mm) at 1 cm offset of the center of the FOV (measured with a 22Na 0.25 mm point‐source), a NEMA sensitivity of 16.4 kcps/MBq, and a NEMA peak NECR of 306 kcps at 32 kBq/mL. TOF resolution varied from 210 to 215 as count‐rate increased up to the peak NECR. The overall image contrast seen with the NEMA image quality phantom ranged from 77.2% to 89.8%. Furthermore, the system was able to comply with the current and future EARL performance criteria. Conclusions: The Biograph Vision outperforms the analog Biograph mCT Flow and the system is able to meet European harmonizing performance standards.
关键词： PET/CT,Digital detectors,NEMA,performance evaluation
更新于2025-09-23 15:22:29
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Study of Sensitivity and Resolution for Full Ring PET Prototypes based on Continuous Crystals and analytical modeling of the light distribution
摘要： Sensitivity and spatial resolution are the main parameters to maximize in the performance of a PET scanner. For this purpose, detectors consisting of a combination of continuous crystals optically coupled to segmented photodetectors have been employed. With the use of continuous crystals the sensitivity is increased with respect to the pixelated crystals. In addition, spatial resolution is no longer limited to the crystal size. The main drawback is the difficulty in determining the interaction position. In this work, we present the characterization of the performance of a full ring based on cuboid continuous crystals coupled to SiPMs. To this end, we have employed the simulations developed in a previous work for our experimental detector head. Sensitivity could be further enhanced by using tapered crystals. This enhancement is obtained by increasing the solid angle coverage, reducing the wedge-shaped gaps between contiguous detectors. The performance of the scanners based on both crystal geometries was characterized following NEMA NU 4-2008 standardized protocol in order to compare them. An average sensitivity gain over the entire axial field of view of 13.63% has been obtained with tapered geometry while similar performance of the spatial resolution has been proven with both scanners. The activity at which NECR and True peak occur is smaller and the peak value is greater for tapered crystals than for cuboid crystals. Moreover, a higher degree of homogeneity was obtained in the sensitivity map due to the tighter packing of the crystals, which reduces the gaps and results in a better recovery of homogeneous regions than for the cuboid configuration. Some of the results obtained, such as spatial resolution, depend on the interaction position estimation and may vary if other method is employed.
关键词： NEMA NU 4-2008,Monte Carlo simulations,image reconstruction,continuous crystals,depth of interaction,positron emission tomography (PET)
更新于2025-09-04 15:30:14