title: A new magnetic resonance head coil and head immobilization device for gamma knife radiosurgery: an analysis of geometric distortion and signal/noise characteristics.
abstract: OBJECTIVE
  The authors report on a new head coil into which the Leksell aluminum localization frame can be easily and securely mounted. Mechanically, the head coil interferes little with the patient.
  
  
  METHODS
  The head coil, which is for magnetic resonance (MR) imaging, is a 12-element quadrature transmit-and-receive high-pass birdcage coil with a nominal operation frequency (63.86 MHz). The coil was built into a plastic housing. This new head coil minimizes patient motion and provides a 20% increase in signal/noise ratios compared with standard head coils. An MR image test phantom was mounted in the coil and this allowed quantification of image distortion due to inhomogeneities in the main magnetic field, nonlinearity in the gradient field, and paramagnetism of the aluminum headframe. There were no significant differences in geometric distortion between the new head coil and the standard coil.
  
  
  CONCLUSIONS
  The new head coil has advantages for reducing patient movement artifacts and has a better signal/noise ratio with no reduction in geometric accuracy.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. jursinic@mcw.edu
authors.forename: Paul
authors.initials: P
authors.lastname: Jursinic
authors.forename: Robert
authors.initials: R
authors.lastname: Prost
authors.forename: Christopher
authors.initials: C
authors.lastname: Schultz
mesh_terms: D016477:Artifacts; D006257:Head; D006801:Humans; D007103:Immobilization; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D019047:Phantoms, Imaging; D016634:Radiosurgery / Q000295:instrumentation*; D013238:Stereotaxic Techniques / Q000295:instrumentation*