Biomedical and atmospheric applications of optical spectroscopy in scattering media

Johannes Swartling

Research output: ThesisDoctoral Thesis (compilation)

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Abstract

Spectroscopic analysis of scattering media is difficult because the effective path length of the light is non-trivial to predict when photons are scattered many times. The main area of research for such conditions is biological tissues, which scatter light because of variations of the refractive index on the cellular level. In order to analyze tissues to diagnose diseases, or predict doses during, for example, laser treatment, it is necessary to be able to model light propagation in the tissue, as well as quantify the scattering and absorption properties. Problems of this type occur in many other areas as well, for example in material science, and atmospheric and ocean-water optics.

This thesis deals with light propagation models in scattering media, primarily based on radiative transport theory. Special attention has been directed to the Monte Carlo model to solve the Boltzmann radiative transport equation, and to develop faster and more efficient computer methods. A Monte Carlo model was applied to solve a spectroscopic problem in monitoring the emission of gases in smoke plumes. An important theme in the thesis deals with measurement of the optical properties, with emphasis on biomedical applications. Several different measurement techniques based on a wide range of instruments have been developed or improved upon, and the strengths and weaknesses of these methods have been evaluated.

The measurement techniques have been applied to analyze the scattering and absorption properties of some biological tissues. Much devotion has been directed to optical characterization of blood, which is an important tissue from a health-care perspective. At present, the complex scattering properties of blood prevents detailed optical analysis of whole blood. The work presented here is also aimed at acquiring a better understanding of the fundamental scattering processes at a cellular level.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Atomic Physics
Supervisors/Advisors
  • Andersson-Engels, Stefan, Supervisor
Award date2002 Dec 13
Publisher
ISBN (Print)91-628-5486-0
Publication statusPublished - 2002

Bibliographical note

Defence details

Date: 2002-12-13
Time: 13:15
Place: Department of Physics, Hall B

External reviewer(s)

Name: Farrell, Thomas J.
Title: Dr
Affiliation: Hamilton Regional Cancer Centre, Hamilton, Ontario, Canada

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Paper I. J. Swartling, A. Pifferi, A. M. K. Enejder, and S. Andersson-Engels, "Accelerated Monte Carlo model to simulate fluorescence spectra from layered tissues," Journal of the Optical Society of America A, in press (2002).
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Paper II. J. Swartling, J. S. Dam, and S. Andersson-Engels, "Comparison of spatially and temporally resolved diffuse reflectance measurement systems for determination of biomedical optical properties," submitted to Applied Optics (2002).
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Paper III. J. Swartling, A. Pifferi, E. Giambattistelli, E. Chikoidze, A. Torri-celli, P. Taroni, M. Andersson, A. Nilsson, and S. Andersson-Engels, "Measurements of absorption and scattering properties using time-resolved diffuse spectroscopy - Instrument characterization and impact of heterogeneity in breast tissue," manuscript (2002).
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Paper IV. J. Swartling, S. Pålsson, P. Platonov, S. B. Olsson, and S. Anders-son-Engels, "Changes in tissue optical properties due to radio-frequency ablation of myocardium," submitted to Medical & Biological Engineering & Computing (2002).
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Paper V. A. M. K. Enejder, J. Swartling, P. Aruna, and S. Andersson-Engels, "Influence of cell shape and aggregate formation on the optical properties of flowing whole blood," Applied Optics, returned after minor revisions (2002).
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Paper VI. J. Swartling, A. M. K. Enejder, P. Aruna, and S. Andersson-Engels, "Polarization-dependent scattering properties of flowing whole blood," manuscript for Applied Optics (2002).
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Paper VII. P. Weibring, J. Swartling, H. Edner, S. Svanberg, T. Caltabiano, D. Condarelli, G. Cecchi, and L. Pantani, "Optical monitoring of volanic sulphur dioxide emissions - Comparison between four different remote-sensing spectroscopic techniques," Optics and Lasers in Engineering 37, 267-284 (2002).

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics

Keywords

  • Turbid media
  • Tissue optics
  • Tissue optical properties
  • Multiple scattering
  • Radiative transfer
  • Diffusion equation
  • Monte Carlo method
  • Time-resolved spectroscopy
  • Atomic and molecular physics
  • Integrating spheres
  • Atom- och molekylärfysik
  • Fysicumarkivet A:2002:Swartling

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