Background
We investigated the image quality of 11C, 68Ga, 18F and 89Zr, which have different positron fractions, physical half-lifes and positron ranges. Three small animal positron emission tomography/computed tomography (PET/CT) systems were used in the evaluation, including the Siemens Inveon, RAYCAN X5 and Molecubes β-cube. The evaluation was performed on a single scanner level using the national electrical manufacturers association (NEMA) image quality phantom and analysis protocol. Acquisitions were performed with the standard NEMA protocol for 18F and using a radionuclide-specific acquisition time for 11C, 68Ga and 89Zr. Images were assessed using percent recovery coefficient (%RC), percentage standard deviation (%STD), image uniformity (%SD), spill-over ratio (SOR) and evaluation of image quantification.
Results
68Ga had the lowest %RC (< 62%) across all systems. 18F had the highest maximum %RC (> 85%) and lowest %STD for the 5 mm rod across all systems. For 11C and 89Zr, the maximum %RC was close (> 76%) to the %RC with 18F. A larger SOR were measured in water with 11C and 68Ga compared to 18F on all systems. SOR in air reflected image reconstruction and data correction performance. Large variation in image quantification was observed, with maximal errors of 22.73% (89Zr, Inveon), 17.54% (89Zr, RAYCAN) and − 14.87% (68Ga, Molecubes).
Conclusions
The systems performed most optimal in terms of NEMA image quality parameters when using 18F, where 11C and 89Zr performed slightly worse than 18F. The performance was least optimal when using 68Ga, due to large positron range. The large quantification differences prompt optimization not only by terms of image quality but also quantification. Further investigation should be performed to find an appropriate calibration and harmonization protocol and the evaluation should be conducted on a multi-scanner and multi-center level.
A: Positron Emission Tomography (PET) is a non-disruptive functional imaging technique, which provides a high resolution and high-sensitivity measurement of the functional processes in biological systems. The recent developments in biology and radio-chemistry enabled PET to study an increasing number of functional processes, but became highly demanding in terms of sensitivity, spatial resolution, and adaptability to the variable size of the biological systems ranging from few millimeters up to several centimeters. In this paper we show how digital signal processing in PET plays an important role in the technological advancement. We report the recent results of digital signal processing methods based on the Multi Voltage Threshold technology, exploring the performances of a series of digital PET systems built upon this principle. We further describe developments of the MVT theory including space-pattern digital signal analysis and the related idea of the integration of the MVT technology within intelligent CMOS SiPM sensors for PET.
Abstract. Considering the complexity of system structure and fault mechanism of complex system, a fault diagnosis method based on extended color fuzzy fault Petri net model is proposed (CFFPN) for civil aircraft. In order to increase the fault diagnosis efficiency, the CFFPN is modeled based on fuzzy mathematics and fault Petri net method through adding token, library and staining rules to describe the fault propagation. Fuzzy generated rules combined with matrix theory are utilized for fault diagnosis reasoning. CFFPN based reasoning algorithm is given. The validity of the proposed method is verified in one type aircraft pneumatic system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.