title: Comparison between a time-domain and a frequency-domain system for optical tomography.
abstract: The quality of phase and amplitude data from two medical optical tomography systems were compared. The two systems are a 32-channel time-domain system developed at University College London (UCL) and a 16-channel frequency-domain system developed at Helsinki University of Technology (HUT). Difference data measured from an inhomogeneous and a homogeneous phantom were compared with a finite-element method (diffusion equation) and images of scattering and absorption were reconstructed based on it. The measurements were performed at measurement times between 1 and 30 s per source. The mean rms errors in the data measured by the HUT system were 3.4% for amplitude and 0.51 deg for phase, while the corresponding values for the UCL data were 6.0% and 0.46 deg, respectively. The reproducibility of the data measured with the two systems was tested with a measurement time of 5 s per source. It was 0.4% in amplitude for the HUT system and 4% for the UCL system, and 0.08 deg in phase for both systems. The image quality of the reconstructions from the data measured with the two systems were compared with several quantitative criteria. In general a higher contrast was observed in the images calculated from the HUT data.
authors.affiliation: Helsinki University of Technology, Laboratory of Biomedical Engineering, 02015 Hut, Finland. ilkka.nissila@hut.fi
authors.forename: Ilkka
authors.initials: I
authors.lastname: Nissilä
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Hebden
authors.forename: David
authors.initials: D
authors.lastname: Jennions
authors.forename: Jenni
authors.initials: J
authors.lastname: Heino
authors.forename: Martin
authors.initials: M
authors.lastname: Schweiger
authors.forename: Kalle
authors.initials: K
authors.lastname: Kotilahti
authors.forename: Tommi
authors.initials: T
authors.lastname: Noponen
authors.forename: Adam
authors.initials: A
authors.lastname: Gibson
authors.forename: Seppo
authors.initials: S
authors.lastname: Järvenpää
authors.forename: Lauri
authors.initials: L
authors.lastname: Lipiäinen
authors.forename: Toivo
authors.initials: T
authors.lastname: Katila
mesh_terms: D000465:Algorithms; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041622:Tomography, Optical / Q000295:instrumentation / Q000379:methods*