The effect of magnetic field on positron range and spatial resolution in an integrated whole-body time-of-flight PET/MRI system

Shih Ying Huang, Dragana Savic, Jaewon Yang, Uttam Shrestha, Youngho Seo

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Scopus citations

Abstract

Simultaneous imaging systems combining positron emission tomography (PET) and magnetic resonance imaging (MRI) have been actively investigated. A PET/MR imaging system (GE Healthcare) comprised of a time-of-flight (TOF) PET system utilizing silicon photomultipliers (SiPMs) and 3-tesla (3T) MRI was recently installed at our institution. The small-ring (60 cm diameter) TOF PET subsystem of this PET/MRI system can generate images with higher spatial resolution compared with conventional PET systems. We have examined theoretically and experimentally the effect of uniform magnetic fields on the spatial resolution for high-energy positron emitters. Positron emitters including 18F, 124I, and 68Ga were simulated in water using the Geant4 Monte Carlo toolkit in the presence of a uniform magnetic field (0, 3, and 7 Tesla). The positron annihilation position was tracked to determine the 3D spatial distribution of the 511-keV gammy ray emission. The full-width at tenth maximum (FWTM) of the positron point spread function (PSF) was determined. Experimentally, 18F and 68Ga line source phantoms in air and water were imaged with an investigational PET/MRI system and a PET/CT system to investigate the effect of magnetic field on the spatial resolution of PET. The full-width half maximum (FWHM) of the line spread function (LSF) from the line source was determined as the system spatial resolution. Simulations and experimental results show that the in-plane spatial resolution was slightly improved at field strength as low as 3 Tesla, especially when resolving signal from high-energy positron emitters in the air-tissue boundary.

Original languageEnglish (US)
Title of host publication2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781479960972
DOIs
StatePublished - Mar 10 2016
Externally publishedYes
EventIEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014 - Seattle, United States
Duration: Nov 8 2014Nov 15 2014

Publication series

Name2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014

Other

OtherIEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
Country/TerritoryUnited States
CitySeattle
Period11/8/1411/15/14

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging

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