&lt;title&gt;Estimation of the optical properties of two-layered tissue simulating phantoms from spatially resolved frequency-domain reflectance&lt;/title&gt;

Alexandrakis, George; Weersink, Robert A.; Bruulsema, J. T.; Patterson, Michael S.

doi:10.1117/12.356806

Cited by 3 publications

(6 citation statements)

References 8 publications

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“…11,12,14 The two-layer FD diffusion model used in the fitting procedures ͑the forward model͒ was used earlier by many authors to model photon propagation in the diffuse regime. 14,20,22 A brief description of the model is presented to assist the reader: The diffusion equations for the fluence rate of a two-layer medium from an intensity-modulated source are given by…”

Section: B Inverse-problem Analysismentioning

confidence: 99%

“…According to Kinel et al, 14 Eqs. ͑3͒ and ͑4͒ are transformed into ordinary differential equations by use of a two-dimensional Fourier transform and solved to yield the fluence solution in frequency space coordinates 1 ͑s, z, ͒ and 2 ͑s, z, ͒ for layers 1 and 2, respectively, by use of the following boundary conditions 20 : zero fluence rate at the extrapolated boundary, finite photon fluence rate as r 3 ϱ, and continuity of fluence rate and flux at the boundary between the two layers.…”

Section: B Inverse-problem Analysismentioning

confidence: 99%

“…For fitting the experimental measurements we assumed a matched boundary condition, and the spatially resolved reflectance was obtained from 20 R͑r, ͒…”

Section: B Inverse-problem Analysismentioning

confidence: 99%

“…18 Few systems and inverse-problem methods have been used to investigate the reflectance measured from multilayer tissues, in particular, with a two-layer model. 14,19,20 Kienle et al 13,14 developed an absolute spatially resolved reflectance-measuring system, using a CCD detector to study multilayer turbid media, and described a two-layer frequencydomain ͑FD͒ diffusion model for data analysis. 14 Pham et al 19 developed a system of FD planar photon density waves that uses modulation frequencies ranging from 10 to 1500 MHz.…”

Section: Introductionmentioning

confidence: 99%

“…Although the approach can be extended to multilayer models in our study we have investigated only a two-layer model that has a finite top-layer thickness ͑2-10 mm͒ and a semi-infinite bottom layer. Such a two-layer model has been used successfully to model many layered-tissue structures such as skin ͑2-4 mm͒ and underlying fat, 19,20 brain and overlying skull ͑ϳ10 mm͒, 16 and muscle and overlying fat and skin ͑4 -10 mm͒. 18 We developed diffuse reflectance-measurement apparatus that measures spatially resolved cw and FD diffuse reflectance by using phantoms to simulate the optical properties of the two-layer tissue.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the optical properties of a two-layer tissue model by detecting photons migrating at progressively increasing depths

Fawzi

Youssef²,

El-Batanony³

et al. 2003

Appl. Opt.

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We have investigated a method for solving the inverse problem of determining the optical properties of a two-layer turbid model. The method is based on deducing the optical properties (OPs) of the top layer from the absolute spatially resolved reflectance that results from photon migration within only the top layer by use of a multivariate calibration model. Then the OPs of the bottom layer are deduced from relative frequency-domain (FD) reflectance measurements by use of the two-layer FD diffusion model. The method was validated with Monte Carlo FD reflectance profiles and experimental measurements of two-layer phantoms. The results showed that the method is useful for two-layer models with interface depths of >5 mm; the OPs were estimated, within a relatively short time (<1 min), with a mean error of <10% for the Monte Carlo reflectance profiles and with errors of <25% for the phantom measurements.

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Section: B Inverse-problem Analysismentioning

confidence: 99%

Section: B Inverse-problem Analysismentioning

confidence: 99%

“…For fitting the experimental measurements we assumed a matched boundary condition, and the spatially resolved reflectance was obtained from 20 R͑r, ͒…”

Section: B Inverse-problem Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Determination of the optical properties of a two-layer tissue model by detecting photons migrating at progressively increasing depths

Fawzi

Youssef²,

El-Batanony³

et al. 2003

Appl. Opt.

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Study of near infrared technology for intracranial hematoma detection

Zhang¹,

Yan

Nioka

et al. 2000

J. Biomed. Opt.

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Although intracranial hematoma detection only requires the continuous wave technique of near infrared spectroscopy (NIRS), previous studies have shown that there are still some problems in obtaining very accurate, reliable hematoma detection. Several of the most important limitations of NIR technology for hematoma detection such as the dynamic range of detection, hair absorption, optical contact, layered structure of the head, and depth of detection are reported in this article. A pulsed light source of variable intensity was designed and studied in order to overcome hair absorption and to increase the dynamic range and depth of detection. An adaptive elastic optical probe was made to improve the optical contact and decrease contact noise. A new microcontroller operated portable hematoma detector was developed. Due to the layered structure of the human head, simulation on a layered medium was analyzed experimentally. Model inhomogeneity tests and animal hematoma tests showed the effectiveness of the improved hematoma detector for intracranial hematoma detection.

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In Vivo Near-Infrared Spectroscopy

Rolfe

2000

Annu. Rev. Biomed. Eng.

231

183

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Interrogation of tissue with light offers the potential for noninvasive chemical measurement, and penetration with near-infrared wavelengths (750-1000 nm) is greater than with visible light. Specific absorption by clinically relevant compounds such as oxy- and deoxyhemoglobin and the intracellular respiratory enzyme cytochrome oxidase enable in vivo measurement of these to be performed safely and conveniently. This is the basis of in vivo near-infrared spectroscopy (ivNIRS). Multiple scattering of the interrogating beam by tissues leads to an optical path that is considerably longer than the simple physical pathlength and this complicates the analysis. Modeling of photon propagation through tissues with, for example, finite element and Monte Carlo methods, is assisting in improving the ivNIRS methodology. Instrumentation has advanced from simple continuous wave approaches, through time-resolved methods based on either time-domain or frequency-domain approaches, to spatially resolved measurement based on diffuse reflectance. Initial clinical applications were for monitoring the brain in the neonate and fetus and muscle in adults. Currently, use in adults and children for neurological assessments are of growing interest.

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<title>Estimation of the optical properties of two-layered tissue simulating phantoms from spatially resolved frequency-domain reflectance</title>

Cited by 3 publications

References 8 publications

Determination of the optical properties of a two-layer tissue model by detecting photons migrating at progressively increasing depths

Determination of the optical properties of a two-layer tissue model by detecting photons migrating at progressively increasing depths

Study of near infrared technology for intracranial hematoma detection

In Vivo Near-Infrared Spectroscopy

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