Spectral determination of a two-parametric phase function for polydispersive scattering liquids

Lindbergh, Tobias; Fredriksson, Ingemar; Larsson, Marcus; Strömberg, Tomas

doi:10.1364/oe.17.001610

Cited by 19 publications

(14 citation statements)

References 23 publications

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“…͑6͒ is used to estimate a ͑a͒ when the coefficients from the simulations are used on the results from the simulations, ͑b͒ when the coefficients from the phantoms are used on the phantoms, and ͑c͒ when the coefficients from the simulations are used on the phantoms. 23 The calculated absorption is higher than it should be for the lower ink concentrations. ͑Color online only.͒ about blood volume in the tissue.…”

Section: Discussionmentioning

confidence: 75%

“…Milk concentrations were varied in steps of 20% between 20 and 100%, and the ink was added in doubling concentrations between 1 / 4000 and 1 / 250, corresponding to peak absorption values from 0.23 to 3.67 mm −1 . 23 The milk was assumed to be a purely scattering medium and the ink a purely absorbing medium. One row of phantoms without ink was also made in order to provide measurements of the pure scattering spectra, I s .…”

Section: Phantom Measurementsmentioning

confidence: 99%

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Spectroscopic method for determination of the absorption coefficient in brain tissue

Johansson

2010

J. Biomed. Opt.

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Abstract. I use Monte Carlo simulations and phantom measurements to characterize a probe with adjacent optical fibres for diffuse reflectance spectroscopy during stereotactic surgery in the brain. Simulations and measurements have been fitted to a modified Beer-Lambert model for light transport in order to be able to quantify chromophore content based on clinically measured spectra in brain tissue. It was found that it is important to take the impact of the light absorption into account when calculating the apparent optical path length, l p , for the photons in order to get good estimates of the absorption coefficient, a . The optical path length was found to be well fitted to the equation l p = a + b ln͑I s ͒ + c ln͑ a ͒ + d ln͑I s ͒ln͑ a ͒, where I s is the reflected light intensity for scattering alone ͑i.e., zero absorption͒. Although coefficients a -d calculated in this study are specific to the probe used here, the general form of the equation should be applicable to similar probes.

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Section: Discussionmentioning

confidence: 75%

Section: Phantom Measurementsmentioning

confidence: 99%

Spectroscopic method for determination of the absorption coefficient in brain tissue

Johansson

2010

J. Biomed. Opt.

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“…Breast tissue is a scattering dominant medium (μ' s >> μ a ) and therefore only scattering properties were considered in the phantom. The scattering coefficient of intralipid at 785 nm was measured with a spectral collimated transmission setup (SCT) [15]. The scattering coefficient of intralipid, μ s (il) [mm -1 ], was related to the intralipid volume concentration, ρ il , by Equation 1 where ρ il is the volume percentage of intralipid 20% in the total phantom volume.…”

Section: Optical Phantommentioning

confidence: 99%

Fluorescence spectroscopy using indocyanine green for lymph node mapping

et al. 2014

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The principles of cancer treatment has for years been radical resection of the primary tumor. In the oncologic surgeries where the affected cancer site is close to the lymphatic system, it is as important to detect the draining lymph nodes for metastasis (lymph node mapping). As a replacement for conventional radioactive labeling, indocyanine green (ICG) has shown successful results in lymph node mapping; however, most of the ICG fluorescence detection techniques developed are based on camera imaging. In this work, fluorescence spectroscopy using a fiber-optical probe was evaluated on a tissue-like ICG phantom with ICG concentrations of 6-64 μM and on breast tissue from five patients. Fiber-optical based spectroscopy was able to detect ICG fluorescence at low intensities; therefore, it is expected to increase the detection threshold of the conventional imaging systems when used intraoperatively. The probe allows spectral characterization of the fluorescence and navigation in the tissue as opposed to camera imaging which is limited to the view on the surface of the tissue.

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“…The scattering and absorption properties of the phantom ingredients were measured using a spectral collimated transmission setup (SCT) [19]. For obtaining the broad spectrum a white light (AvaLight-Hal-S, Avantes, Apeldoorn, Netherlands) and for obtaining optical properties at 405 nm, a blue laser light was used.…”

Section: Spectral Collimated Transmissionmentioning

confidence: 99%

Development and characterization of a brain tumor mimicking fluorescence phantom

2014

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Fluorescence guidance using 5-aminolevulinic acid (5-ALA) for brain tumor resection is a recent technique applied to the highly malignant brain tumors. Five-ALA accumulates as protoporphyrin IX fluorophore in the tumor cells in different concentrations depending on the tumor environment and cell properties. Our group has developed a fluorescence spectroscopy system used with a hand-held probe intra-operatively. The system has shown improvement of fluorescence detection and allows quantification that preliminarily correlates with tumor malignancy grade during surgery. However, quantification of fluorescence is affected by several factors including the initial fluorophore concentration, photobleaching due to operating lamps and attenuation from the blood. Accordingly, an optical phantom was developed to enable controlled fluorescence measurements and evaluation of the system outside of the surgical procedure. The phantom mimicked the optical properties of glioma at the specific fluorescence excitation wavelength when different concentrations of the fluorophore were included in the phantom. To allow evaluation of photobleaching, kinetics of fluorophore molecules in the phantom was restricted by solidifying the phantoms. Moreover, a model for tissue autofluorescence was added. The fluorescence intensity's correlation with fluorophore concentration in addition to the photobleaching properties were investigated in the phantoms and were compared to the clinical data measured on the brain tumor.

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Spectral determination of a two-parametric phase function for polydispersive scattering liquids

Cited by 19 publications

References 23 publications

Spectroscopic method for determination of the absorption coefficient in brain tissue

Spectroscopic method for determination of the absorption coefficient in brain tissue

Fluorescence spectroscopy using indocyanine green for lymph node mapping

Development and characterization of a brain tumor mimicking fluorescence phantom

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