Frequency-domain measurements of photon migration in tissues

Lakowicz, Joseph R.; Berndt, Klaus W.

doi:10.1016/0009-2614(90)80024-8

Cited by 100 publications

(49 citation statements)

References 22 publications

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“…Linear fits to + versus X and -n(m) versus W 2 furnish constant slopes, mi, and Miln(m), respectively, which can be used to calculate 13 (independent of r): (23) 4c X mi(m) Linear-fit 13 values obtained from 5-, 10-, 15-, and 20-MHz data at six different source-detector distances are summarized in Table 2. These results are in reasonable agreement with full-fit 1 values; however, since only a few frequencies were available to satisfy oAr < 0.7, full-fit methods should be more accurate.…”

Section: Cmentioning

confidence: 99%

Properties of photon density waves in multiple-scattering media

et al. 1993

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Amplitude-modulated light launched into multiple-scattering media, e.g., tissue, results in the propagation of density waves of diffuse photons. Photon density wave characteristics in turn depend on modulation frequency () and media optical properties. The damped spherical wave solutions to the homogeneous form of the diffusion equation suggest two distinct regimes of behavior: (1) a highfrequency dispersion regime where density wave phase velocity V has a /; dependence and (2) a low-frequency domain where V, is frequency independent. Optical properties are determined for various tissue phantoms by fitting the recorded phase () and modulation (m) response to simple relations for the appropriate regime. Our results indicate that reliable estimates of tissuelike optical properties can be obtained, particularly when multiple modulation frequencies are employed.

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Section: Cmentioning

confidence: 99%

Properties of photon density waves in multiple-scattering media

et al. 1993

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“…Because in time-resolved measurements the separation between absorption and scattering occurs by the term exp(Àl a ct), this gave an impulse to develop time-resolved spectroscopy [13,14], and later frequency-domain photon-diffusion [15,16] which have been applied to biological tissue with the aim to obtain the absorption and scattering coefficients of the tissue separately, and also to improve the possibilities for imaging in biological tissue [17].…”

Section: Introductionmentioning

confidence: 99%

Telegrapher’s equation for light derived from the transport equation

Hoenders

Graaff

2005

Optics Communications

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Shortcomings of diffusion theory when applied to turbid media such as biological tissue makes the development of more accurate equations desirable. Several authors developed telegrapherÕs equations in the well known P 1 approximation. The method used in this paper is different: it is based on the asymptotic evaluation of the solutions of the equation of radiative transport with respect to place and time for all values of the albedo. Various coefficients for the telegrapherÕs equations were derived, restricted to the case of isotropic scattering, and their properties are discussed. A correct diffusion coefficient for the stationary case could be obtained. However, this solution did not lead to the correct phase velocity. Correct phase velocities in combination with a correct diffusion coefficient were found for a dispersion relation that corresponds with anisotropic Henyey-Greenstein scattering with g = 0.22. It provides a time-dependent description of the fluence rate with validity for all values of the albedo.

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“…There are basically two ways that one can perform FDPM measurements: either by varying the source-detector distance while modulating the light at a fixed modulation frequency 14 or by keeping the source and detector at fixed positions and sweeping over a range of frequencies. 13,15,16 In our experiments, the source-detector separation was kept constant during the measurement session while radio-frequency ͑rf ͒ modulation was swept up to 1 GHz.…”

Section: Introductionmentioning

confidence: 99%

Optical property measurements of turbid media in a small-volume cuvette with frequency-domain photon migration

2001

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A frequency-domain photon migration ͑FDPM͒ technique is developed for quantitative measurement of the absorption and reduced scattering coefficients of highly turbid samples in a small-volume ͑0.45-ml͒ reflective cuvette. We present both an analytical model for the FDPM cuvette and its experimental verification, using calibrated phantoms and suspensions of living cells. FDPM model fits to experimental data demonstrate that the reduced scattering ͑ s Ј͒ and absorption ͑ a ͒ coefficients can be derived with accuracies of 5-10% and 10 -15%, respectively. Changing the cuvette wall reflectivity alters the frequency-dependent behavior of photon density waves ͑PDWs͒. For highly reflective wall boundaries ͑R eff Ն 90 -95%͒, PDW confinement leads to substantial enhancement in both amplitude and phase compared with identical samples in infinite media. Results from experiments on microsphere suspensions are compared with predictions from Mie theory to assess the potential of this method to interpret scattering properties in terms of scatterer size and density. Optical property measurements of biological cell suspensions are reported, and the possibility of optically monitoring cell physiology in a carefully controlled environment is demonstrated.

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Frequency-domain measurements of photon migration in tissues

Cited by 100 publications

References 22 publications

Properties of photon density waves in multiple-scattering media

Properties of photon density waves in multiple-scattering media

Telegrapher’s equation for light derived from the transport equation

Optical property measurements of turbid media in a small-volume cuvette with frequency-domain photon migration

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