TY - GEN
T1 - Experimental measurements on phantoms and Monte Carlo simulation to evaluate the effect of inhomogeneity on optical pathlength
AU - Okada, Eiji
AU - Firbank, Michael
AU - Schweiger, Martin
AU - Arridge, Simon R.
AU - Hebden, Jeremy C.
AU - Hiraoka, Mutsuhisa
AU - Delpy, David T.
N1 - Funding Information:
This work was supported by Japan Society for the Promotion of Science, Postdoctoral Fellowship for Research Abroad to E. Okada, and funding from EPSRC, the Wellcome Trust and Hamamatsu Photonics KK.
Publisher Copyright:
© 2018 SPIE.
PY - 1995/5/30
Y1 - 1995/5/30
N2 - Determination of the optical pathlength of light in tissue is important to quantitate NIRS data. However, the inhomogeneity of the illuminated tissues increases the difficulty of determining the relevant optical pathlength in the tissue. For instance, in the head, the contribution of the tissues overlying the brain to the total optical pathlength cannot be ignored in the monitoring of cerebral oxygenation with NIRS. In this study, time-of-flight measurements of an inhomogeneous phantom are carried out in the laboratory to examine the contribution of the overlying tissue to the optical pathlength. The phantom consists of two homogeneous components, the boundaries of which are two concentric cylinders. The TPSF is measured with a picosecond laser and a streak camera, and the change of TPSF with the distance between source and detection fibers is examined. The experimental TPSF and mean time of flight are compared with the results of a Monto Carlo simulation and a finite element model based on the diffusion equation. A comparison of the accuracy of prediction of the pathlength by each model is presented as a function of the spacing between source and detection fibers. The intensity photon measurement density functions in each of the cylinders were estimated from the Monte Carlo simulations. The results provide estimates for the amount of the NIRS signal arising from overlying tissues in the head.
AB - Determination of the optical pathlength of light in tissue is important to quantitate NIRS data. However, the inhomogeneity of the illuminated tissues increases the difficulty of determining the relevant optical pathlength in the tissue. For instance, in the head, the contribution of the tissues overlying the brain to the total optical pathlength cannot be ignored in the monitoring of cerebral oxygenation with NIRS. In this study, time-of-flight measurements of an inhomogeneous phantom are carried out in the laboratory to examine the contribution of the overlying tissue to the optical pathlength. The phantom consists of two homogeneous components, the boundaries of which are two concentric cylinders. The TPSF is measured with a picosecond laser and a streak camera, and the change of TPSF with the distance between source and detection fibers is examined. The experimental TPSF and mean time of flight are compared with the results of a Monto Carlo simulation and a finite element model based on the diffusion equation. A comparison of the accuracy of prediction of the pathlength by each model is presented as a function of the spacing between source and detection fibers. The intensity photon measurement density functions in each of the cylinders were estimated from the Monte Carlo simulations. The results provide estimates for the amount of the NIRS signal arising from overlying tissues in the head.
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U2 - 10.1117/12.209965
DO - 10.1117/12.209965
M3 - Conference contribution
AN - SCOPUS:85010164963
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 174
EP - 181
BT - Optical Tomography, Photon Migration, and Spectroscopy of Tissue and Model Media
A2 - Chance, Britton
A2 - Alfano, Robert R.
PB - SPIE
T2 - Optical Tomography, Photon Migration, and Spectroscopy of Tissue and Model Media: Theory, Human Studies, and Instrumentation
Y2 - 1 February 1995 through 28 February 1995
ER -