title: Optimized RF shielding techniques for simultaneous PET/MR.
abstract: OBJECTIVE
  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.
authors.affiliation: Institute of Experimental Molecular Imaging, Pauwelsstrafle 20, 52074 Aachen and Philips Research Europe-Aachen, Weisshausstr. 2, 52066 Aachen, Germany. daniel.truhn@googlemail.com
authors.forename: D
authors.initials: D
authors.lastname: Truhn
authors.forename: F
authors.initials: F
authors.lastname: Kiessling
authors.forename: V
authors.initials: V
authors.lastname: Schulz
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011835:Radiation Protection / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000295:instrumentation*