title: Optical fibre-based goniometer for sensing patient position and movement within a magnetic resonance scanner using chromatic modulation.
abstract: An optical fibre-based goniometer is described. This instrument was designed to measure the angular position of patients' limbs within the core of a magnetic resonance body scanner, via a 40 m remote fibre-optic link. The sensor exploits the advantages of optical fibre-based sensing, which include immunity to electromagnetic interference, intrinsic safety and chemical immunity. The detection electronics and signal processing are based on the principles of chromatic modulation, an inexpensive, intensity-independent technique in which a change in the spectral power distribution is measured over a broad bandwidth, by photodetectors with differing spectral responses. The optical fibre goniometer has an angular range of 90 degrees, with an average resolution of 2'. The long-term accuracy is within +/- 1 degree, the specified accuracy for the physiological application.
authors.affiliation: Division of Engineering and Science, Liverpool John Moores University, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Scully
authors.forename: R
authors.initials: R
authors.lastname: Holmes
authors.forename: G R
authors.initials: GR
authors.lastname: Jones
mesh_terms: D016477:Artifacts; D004574:Electromagnetic Fields; D005069:Evaluation Studies as Topic; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009068:Movement; D011187:Posture; D012815:Signal Processing, Computer-Assisted; D013053:Spectrophotometry / Q000295:instrumentation