Optimized RF shielding techniques for simultaneous PET/MR

Purpose: Integration of positron emission tomography (PET) and magnetic resonance (MR) in a merged device requires shielding of the PET detector electronics. The authors demonstrate that a multiple shell setup exhibits advantages over a single shell shielding enclosure. Methods: A spherical shell model is used to derive analytical results. Numerical computations of the electromagnetic fields with a commercial software package (FEKO) and experiments are used to confirm our findings. Results: Replacing a single shell enclosure by a multilayer approach barely changes its behavior toward low frequency magnetic fields (MR gradient fields), while improving shielding at high frequencies (proton resonant frequency) by orders of magnitude. Conclusions: For a given required shielding factor at the proton resonant frequency, the eddy currents induced by the MR gradient fields may be reduced by employing a multiple shell setup. (C) 2011 American Association of Physicists in Medicine. [DOI:10.1118/1.3596532]