Assessment of an in situ temporal calibration method for time-resolved optical tomography.
A 32-channel time-resolved optical imaging device is developed at University College London to produce functional images of the neonatal brain and the female breast. Reconstruction of images using time-resolved measurements of transmitted light requires careful calibration of the temporal characteristics of the measurement system. Since they can often vary over a period of time, it is desirable to evaluate these characteristics immediately after, or prior to, the acquisition of image data. A calibration technique is investigated that is based on the measurement of light back-reflected from the surface of the object being imaged. This is facilitated by coupling each detector channel with an individual source fiber. A Monte Carlo model is employed to investigate the influence of the optical properties of the object on the back-reflected signal. The results of simulations indicate that their influence may be small enough to be ignored in some cases, or could be largely accounted for by a small adjustment to the calibrated data. The effectiveness of the method is briefly demonstrated by imaging a solid object with tissue-equivalent optical properties.
Hebden
Jeremy C
JC
University College London, Department of Medical Physics & Bioengineering, 11-20 Capper Street, London WC1E 6JA, UK. jem@medphys.ucl.ac.uk
Gonzalez
Felipe M
FM
Gibson
Adam
A
Hillman
Elizabeth M C
EM
Yusof
Rozarina Md
RM
Everdell
Nick
N
Delpy
David T
DT
Zaccanti
Giovanni
G
Martelli
Fabrizio
F
D001921:Brain / Q000033:anatomy & histology; D001940:Breast / Q000033:anatomy & histology; D004582:Electronics, Medical / Q000295:instrumentation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D009010:Monte Carlo Method; D055095:Optics and Photonics / Q000295:instrumentation; D019047:Phantoms, Imaging; D014054:Tomography / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data