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Purpose: The positron range and prompt gamma emission are distinctive with different positron emitters. The performance assessment of an integrated PET/MR scanner with these positron emitters is required for related applications, as the magnetic field interferes with the positron propagation. Such an assessment is to be performed on the United Imaging uPMR 790-integrated PET/MR system.
Methods: The performance measurement methods were modified based on NEMA NU 2-2012, involving F, Cu, Ga, Zr, and I as positron emitters. The NEMA IEC phantom was used for evaluations of image qualities. An agarose cap was wrapped around the point source for tissue-simulating spatial resolution measurement. The count rate performance was assessed with selected positron emitters. Images of a 3D-printed Derenzo phantom and representative patients were also acquired.
Results: The image quality measurement showed that all five positron emitters were suitable for the PET/MR system studied. However, due to the magnetic field, the image of the point source showed an elongated comet-tail feature, which could be eliminated by a tissue-simulating cap. This effect is more obvious in I and Ga, due to their long positron ranges. The imaging ability with various positron emitters was further validated with the count rate assessment, the Derenzo phantom, and the clinical images.
Conclusions: Different positron emitters could be effectively imaged by the PET/MR system tested. The resolution measurement strategy proposed could be applied to measure PET spatial resolution in the magnetic field.
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http://dx.doi.org/10.1002/mp.15513 | DOI Listing |
Appl Radiat Isot
August 2025
Radioisotope Centre POLATOM, National Centre for Nuclear Research, Andrzeja Sołatana 7, 05-400 Otwock, Poland.
Terbium-161 (T = 6.89 d) is a low-energy β emitter (β 460 and 522 keV). It also emits γ radiation (25.
View Article and Find Full Text PDFIEEE Trans Radiat Plasma Med Sci
April 2025
Department of Radiology, University of Chicago, Chicago, IL 60637.
Positron emission tomography (PET) is an important modality for diagnosing diseases such as cancer and Alzheimer's disease, capable of revealing the uptake of radiolabeled molecules that target specific pathological markers of the diseases. Recently, positronium lifetime imaging (PLI) that adds to traditional PET the ability to explore properties of the tissue microenvironment beyond tracer uptake has been demonstrated with time-of-flight (TOF) PET and the use of non-pure positron emitters. However, achieving accurate reconstruction of lifetime images from data acquired by systems having a finite TOF resolution still presents a challenge.
View Article and Find Full Text PDFSci Rep
August 2025
G. V. Kurdyumov Institute for Metal Physics, N.A.S. of Ukraine, 36 Academician Vernadsky Blvd., Kyiv, 03142, Ukraine.
This work explores the potential of conductive polymer-carbon nanocomposites, specifically polytetrafluoroethylene with multi-walled carbon nanotubes (PTFE-CNTs), as efficient electron emitters for emission electronics, low-temperature thermionic energy conversion (TEC), sensors, elements of information storage devices, and materials with targeted control of electromagnetic waves' absorption/reflection. Our main scientific contribution is the demonstration of electron emission from investigated composite PTFE + 10 wt% CNTs at significantly reduced operating temperatures (near 200 °C), much lower than those for pure CNTs and conventional materials for emission electronics and energy. The research combines experimental studies of electron emission under concentrated solar and pulsed laser radiation, structural characterization of samples by electron microscopy, and positron spectroscopy.
View Article and Find Full Text PDFPhys Med Biol
August 2025
Nuclear Physics Group, EMFTEL and IPARCOS, Universidad Complutense de Madrid (UCM), Av. Complutense, Pl. de las Ciencias 1, Madrid 28040, Spain.
The positron range (PR) effect is a significant factor limiting spatial resolution in positron emission tomography (PET), particularly for high-resolution systems and non-standard isotopes.This study introduces a novel analytical model to accurately and rapidly describe PR distributions (PRd) for various PET radioisotopes to better include its effect in PET reconstruction algorithms.The proposed model explicitly incorporates the Coulomb repulsion effect, the multi-branch nature of certainβ+emitters, and the scaling of PR with electronic density.
View Article and Find Full Text PDFBiomedicines
June 2025
Nuclear Medicine Unit, Department of Onco-Hematology, Fondazione PTV Policlinico Tor Vergata University Hospital, 00133 Rome, Italy.
Positron emission tomography (PET) imaging targeting glypican-3 (GPC3) holds promise for improving the detection and characterization of hepatocellular carcinoma (HCC). Preclinical and early clinical studies have largely utilized high-molecular-weight antibodies radiolabeled with isotopes such as Zr and I, demonstrating high affinity and tumor uptake but suffering from prolonged circulation times and suboptimal signal-to-background ratios. To address these limitations, interest has shifted toward low-molecular-weight vectors-synthetic peptides and small antibody fragments-labeled with shorter-lived radionuclides (e.
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