Positron range effects of 66Ga in small-animal PET imaging
Autor: | Miguel A. Avila-Rodriguez, E.M. Hernández, Mercedes Rodríguez-Villafuerte, Héctor Alva-Sánchez, Arnulfo Martínez-Dávalos |
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Rok vydání: | 2019 |
Předmět: |
Range (particle radiation)
Materials science Image quality business.industry Biophysics General Physics and Astronomy General Medicine Imaging phantom 030218 nuclear medicine & medical imaging 03 medical and health sciences Full width at half maximum 0302 clinical medicine Positron Optics 030220 oncology & carcinogenesis Radiology Nuclear Medicine and imaging business Image resolution Preclinical imaging Line Spread Function |
Zdroj: | Physica Medica. 67:50-57 |
ISSN: | 1120-1797 |
Popis: | Purpose Gallium-66 is a non-conventional positron emitter that stands out not only for its high potential to label peptides, proteins and antibodies, but also because it can provide spatio-temporal information of relatively slow physiological processes in the body due to its conveniently long half-life of 9.5 h. However, 66Ga emits the most energetic positrons for PET imaging. The lack of information of the positron range effect on spatial resolution for this positron emitter is an issue, particularly in preclinical imaging. Methods The line spread function (LSF) in tissue-equivalent materials with densities between 0.2 and 1.93 g/cm3 was obtained with 66Ga and 18F. A complementary study with the NEMA NU 4-2008 image quality phantom is also included. Results High-energy positrons moving in lower density materials produce far-reaching activity distributions. The LSFs were characterized with Lorentzian-Gaussian fits, with spatial resolution (FWHM) in the 2.14–3.2 mm range, and long tails extending a few tens of mm depending on the material type and density. A narrowing of the LSF was observed for lung-equivalent materials, indicating the lack of enough material for the positron annihilation to take place. The NEMA NU 4-2008 image quality phantom produced blurred images, notoriously observed in the hot and cold cylinders used for evaluation of recovery coefficients (RC) and spill-over ratios (SOR), producing very low RC and very large SOR. Conclusions Quantitative PET imaging with the non-conventional 66Ga is hampered due to the large range of its high-energy positrons affecting both spatial resolution and activity concentration quantification. |
Databáze: | OpenAIRE |
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