Simulation of scattering and attenuation of 511 keV photons in a combined PET/field-cycled MRI system

William B. Handler, Kyle M. Gilbert, Hao Peng, Blaine A. Chronik

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Mixing the imaging modalities of positron emission tomography (PET) and magnetic resonance imaging (MRI) will offer the best soft tissue contrast (MRI) with information about metabolic function (PET). The high magnetic field environment of an MRI system makes the detection of annihilation photons difficult, as the response of standard photo-multiplier tubes is compromised. An approach using field-cycled MRI is discussed here, as field-cycled MRI makes it possible to have long periods of time available for nuclear imaging when there is no magnetic field present. This work focuses upon the effect of the field-cycled MRI upon the nuclear image due to the added material providing additional attenuation of the PET signal, and additional nuclei for scatter. These effects are studied using a Monte Carlo simulation based upon the GEANT libraries. Attenuation effects are shown to be significant, approximately 6% for the RF shield and coil and approximately 24% for the gradients. No significant effect is seen in image quality due to the scattering of the gammas. With these levels of attenuation it is concluded that open gradient coils and shim coils are required around the imaging volume.

Original languageEnglish (US)
Pages (from-to)2479-2491
Number of pages13
JournalPhysics in medicine and biology
Volume51
Issue number10
DOIs
StatePublished - May 21 2006
Externally publishedYes

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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