Abstract
Monte Carlo simulation of photon migration in tissue was used to assess the sampling depth, measuring depth and photon pathlength in laser Doppler flowmetry. The median sampling depth and photon pathlength in skin, liver and brain tissue were calculated for different probe geometries. The shallowest median sampling depth found was 68 μm for a 120 μm diameter single fibre probe applied to a one-layered skin tissue model. By using separate transmitting and receiving fibres, the median sampling depth, which amounted to 146 μm for a 250 μm fibre centre separation, by be successively increased to 233 μm when the fibres' centres are separated by 700 μm. Total photon pathlength and thereby the number of multiple Doppler shifts increase with fibre separation, thus favouring the choice of a probe with a small fibre separation when linearity is more important than a large sampling depth. Owing mainly to differences in the tissue g-value and scattering coefficient, the median sampling depth is shallower for liver and deeper for brain, in comparison with skin tissue. For skin tissue, the influence on the sampling depth of a homogeneously distributed blood volume was found to be limited to about 1 per cent per percentage increase in tissue blood content, and may, therefore, be disregarded in most practical situations. Simulations show that the median measuring depth is strongly dependent on the perfusion profile.
Similar content being viewed by others
References
Ahn, H., Lindhagen, J., Nilsson, G. E., Salerud, E. G., Jodal, M. andLundgren, O. (1985) Evaluation of laser Doppler flowmetry in the assessment of intestinal blood flow in cat.Gastroenterol.,88, 951–957.
Borgos, J. A. (1990) TSI's LDV blood flowmeter. InLaser Doppler blood flowmetry.Shepherd, P. andÖberg, P. -Å. (Eds.) Kluwer Academic Publishers, 73–92.
Braverman, I. M., Keh, A. andGoldminz, D. (1990) Correlation of laser Doppler wave patterns with underlying microvascular anatomy.J. Invest. Dermatol.,95, 283–286.
Chandrasekhar, S. (1960)Radiative transfer, Dover, New York.
Crilly, R. J. (1987) The transport of infrared radiation in biological tissue. M.Sc. Thesis, University of Alberta.
Flock, S. T., Patterson, M. S., Wilson, B. C. andWyman, D. R. (1989a) Monte Carlo modeling of light propagation in highly scattering tissues—I: Model predictions and comparison with diffusion theory.IEEE Trans.,BME-36, 1162–1168.
Flock, S. T., Wilson, B. C. andPatterson, M. S. (1989b) Monte Carlo modeling of light propagation in highly scattering tissues—II: Comparison with measurements in phantoms. —Ibid.,,BME-36, 1169–1173.
Henyey, L. G. andGreenstein, J. L. (1941) Diffuse radiation in the galaxy.Astrophys. J.,93, 70–83.
Hirata, K., Nagasaka, T. andNoda, Y. (1988) Partitional measurement of capillary and arteriovenous anastomotic blood flow in the human finger by laser-Doppler-flowmetry.Eur. J. Appl. Physiol.,57, 616–621.
Holloway, G. A. Jr. (1990) Medpacific's LDV blood flowmeter. InLaser Doppler blood flowmetry.Shepherd, P. andÖberg, P. -Å. (Eds.) Kluwer Academic Publishers, 47–56.
Ishimaru, A. (1978)Wave propagation and scattering in random media. Academic Press, New York, 175–190.
Johansson, K., Ahn, H., Lindhagen, J. andLundgren, O. (1987) Tissue penetration and measuring depth of laser Doppler flowmetry in the gastrointestinal application.Scand. J. Gastroenterol.,22, 1081–1088.
Johansson, K., Jakobsson, A., Lindahl, J., Lundgren, O. andNilsson, G. E. (1991) Influence of fibre diameter and probe geometry on the measuring depth of laser Doppler flowmetry in the gastrointestinal application.Int. J. Microcirc.: Clin. Exp.,10, 219–229.
Johnson, J. M. (1990) The cutaneous circulation. InLaser Doppler blood flowmetry.Shepherd, P. andÖberg, P. -Å. (Eds.) Kluwer Academic Publishers, 121–139.
Kiel, J. W., Riedel, G. L., Diresta, G. R. andShepherd, A. P. (1985) Gastric mucosal blood flow measured by laser Doppler velocimetry.Am. J. Physiol.,249G, 539–545.
Marchesini, R., Bertoni, A., Andreola, E., Molloni, E. andSichirollo, A. E. (1989) Extinction and absorption coefficients and scattering phase functions of human tissues in vitro.Appl. Opt.,28, 2318–2324.
Nilsson, G. E., Tenland, T. andÖberg, P. Å. (1980a) A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy.IEEE Trans.,BME-27, 12–19.
Nilsson, G. E., Tenland, T. andÖberg, P. Å. (1980b) Evaluation of a laser Doppler flowmeter for measurement of tissue blood flow. —Ibid.,,BME-27, 597–604.
Nilsson, G. E. (1984) Signal processor for laser Doppler tissue flowmeters.Med. & Biol. Eng. & Comput.,22, 343–348.
Nilsson, G. E., Jakobsson, A. andWårdell, K. (1989) Imaging of tissue blood flow by coherent light scattering. In Proc. IEEE 11th Ann. EMBS Conf., Seattle, Nov. 9–12.
Nilsson, G. E. (1990) Perimed's LDV flowmeter. InLaser Doppler blood flowmetry.Shepherd, P. andÖberg, P. -Å. (Eds.), Kluwer Academic Publishers, 57–73.
Reynolds, R., Johnson, C. andIshimaru, A. (1976) Diffuse reflectance from a finite blood medium: applications to the modeling of fiber optic catheters.Appl. Opt.,15, 2059–2067.
Rothman, S. (1954)Physiology and Biochemistry of the Skin. The University of Chicago Press, Chicago & London, 61–64.
Salerud, E. G. andNilsson, G. E. (1986) Integrating probe for tissue laser Doppler flowmeters.Med. & Biol. Eng. & Comput.,24, 415–419.
Splinter, R., Cheong, W. F., van Gemert, M. J. C. andWelch, A. J. (1989) In vitro optical properties of human and canine brain and urinary bladder tissues at 633 nm.Lasers in Surg. & Med.,9, 37–41.
van Gemert, M. J. C., Jacoues, S. L., Sterenborg, H. J. C. M. andStar, W. M. (1989) Skin optics.IEEE Trans.,BME-36, 1146–1154.
Welch, A. J., Yoon, G. andvan Gemert, M. J. C. (1987) Practical models for light distributions in laser-irradiated tissue.Lasers in Surg. & Med.,6, 488–493.
Weiss, G. H., Nossal, R. andBonner, R. F. (1989) Statistics of penetration depth of photons re-emited from irradiated tissue.J. Mod. Opt.,36, 349–359.
Wilson, B. C. andAdam, G. (1983) A Monte Carlo model for the absorption and flux distributions of light in tissue.Med. Phys.,10, 824–830.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jakobsson, A., Nilsson, G.E. Prediction of sampling depth and photon pathlength in laser Doppler flowmetry. Med. Biol. Eng. Comput. 31, 301–307 (1993). https://doi.org/10.1007/BF02458050
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02458050