Comparison between a time-domain and a frequency-domain system for optical tomography.
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.
Nissilä
Ilkka
I
Helsinki University of Technology, Laboratory of Biomedical Engineering, 02015 Hut, Finland. ilkka.nissila@hut.fi
Hebden
Jeremy C
JC
Jennions
David
D
Heino
Jenni
J
Schweiger
Martin
M
Kotilahti
Kalle
K
Noponen
Tommi
T
Gibson
Adam
A
Järvenpää
Seppo
S
Lipiäinen
Lauri
L
Katila
Toivo
T
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*