Two steady-state methods for localizing a fluorescent inhomogeneity in a turbid medium

Thomas H. Foster, Edward L. Hull, Michael G. Nichols, David S. Rifkin, Nina Schwartz

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We present two cw methods for localizing a source of fluorescence buried in a medium with optical properties similar to those of tissue in the near infrared region. The first approach is based on the fact that, for small excitation beam diameters, the absolute intensity at a given depth in the medium depends on the diameter of the incident beam. For a well-chosen pair of beam diameters, the ratio of these intensities in a scattering medium depends uniquely on the depth from the surface of incidence. Thus, the ratio of the fluorescence resulting from sequential excitation using two beam diameters can be used to determine the depth at which the fluorescence originated. The second method is based on spatially resolved surface measurements of the diffuse fluorescence from the buried source. Using a form of the diffusion theory analysis of Farrell et al. (Med. Phys., 1992) for the spatially resolved diffuse reflectance from a pencil beam incident on a scattering medium, it is possible to reconstruct the depth of the source from the shape of the surface fluorescence profile. Preliminary experimental results obtained using a 1.0 cm diameter sphere containing the tumor localizing fluorophore Nile Blue A show that the spatially resolved measurement reports the location of fluorescent sources as deep as 4.0 cm with an accuracy of 0.4 cm or better.

Original languageEnglish
Pages (from-to)741-749
Number of pages9
JournalUnknown Journal
Volume2979
DOIs
StatePublished - 1997
Externally publishedYes

Fingerprint

inhomogeneity
Fluorescence
fluorescence
Scattering
pencil beams
diffusion theory
Fluorophores
Surface measurement
scattering
excitation
Tumors
tumors
Optical properties
incidence
Tissue
Infrared radiation
reflectance
optical properties
profiles

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Two steady-state methods for localizing a fluorescent inhomogeneity in a turbid medium. / Foster, Thomas H.; Hull, Edward L.; Nichols, Michael G.; Rifkin, David S.; Schwartz, Nina.

In: Unknown Journal, Vol. 2979, 1997, p. 741-749.

Research output: Contribution to journalArticle

Foster, Thomas H. ; Hull, Edward L. ; Nichols, Michael G. ; Rifkin, David S. ; Schwartz, Nina. / Two steady-state methods for localizing a fluorescent inhomogeneity in a turbid medium. In: Unknown Journal. 1997 ; Vol. 2979. pp. 741-749.
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