&lt;title&gt;Application of near-field interference of phase-modulated spectroscopy for detection of absorbers: theoretical prediction of phase shift with respect to the location of the absorber by using a probabilistic-numerical technique, the B-W-K method&lt;/title&gt;

Kang, Kyung A.; Chance, Britton; Bruley, Duane F.; Londoño, John Makario

doi:10.1117/12.154652

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…The 10 cm region ͑from x ϭϪ5 cm to xϭϩ5 cm) is discretized into 64 grids. The charts show that there is an amplitude null and phase transition of 180°in the middle plane across the midpoint between two sources, which agrees with previous simulation results by Kang et al 13 When the detector is in the left side of both sources, it receives larger light signal from the left source (S1) than the right source (S2) since S1 has a shorter distance. This causes the phase signal to be predominated by S1.…”

Section: Theorysupporting

confidence: 90%

“…Fig. 13 The summation of total signals from four stimulus on one day versus the date of testing (indicated by the date after birth and resuscitation), which shows the signal variation with different brain conditions. Note that there is almost no signal after the seizure (date 3) and the signal recovers gradually and finally reaches a normal value before the infant left the hospital (date 21).…”

Section: Discussionmentioning

confidence: 99%

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Preliminary evaluation of dual wavelength phased array imaging on neonatal brain function

et al. 2000

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Imaging of human tissue using noninvasive techniques has been of great interest in biomedical fields. Optical imaging has attracted a lot of attention because of its portability and economy. The possibility that a highly portable, fast, safe, and affordable imaging system which could obtain interpretable images of brain function for pre- and full-term neonates in a few seconds, has been explored in this article. We have used a sensitive optical topography system, termed phased array, in which a pair of equal-amplitude and antiphase light sources are applied to generate a sharp amplitude null and phase transition plane. This two-wavelength (750 and 830 nm), frequency encoded (50 and 52 MHz) phased array imaging system can indicate the blood concentration and oxygenation changes in blood model studies and during parietal brain activation in neonates. Significant functional responses, particularly to parietal stimulation in normal and pathological states of neonatal brain, have been revealed in our study. The preliminary clinical results are presented in this article.

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confidence: 90%

Section: Discussionmentioning

confidence: 99%

Preliminary evaluation of dual wavelength phased array imaging on neonatal brain function

et al. 2000

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“…A pulse of light propagating in a turbid medium can be thought of as a superposition of many DPDWs with different modulation frequencies. Thus, a timeresolved measurement ofthe propagation of a light pulse is an easy way to determine the frequency response of the system (19). To calculate the response to a pulse of light, we simply compute the scattering due to each DPDW in parallel.…”

Section: Resultsmentioning

confidence: 99%

Scattering of diffuse photon density waves by spherical inhomogeneities within turbid media: analytic solution and applications.

Boas

O’Leary

Chance

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

238

136

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We present an analytic solution for the scattering of diffuse photon density waves by spherical inhomogeneities within turbid media. The analytic result is compared to experimental measurements. Close agreement between theory and experiment permits the use of the theory to determine the properties of unknown sphere-like objects embedded in turbid media. The analytic solution is extended to encompass several problems of practical interest in imaging, including the influence of multiple sources, multiple objects, and boundaries on the characterization of spherical inhomogeneities. We also extend the solution to encompass time-domain measurements.Recently, useful information about turbid media such as human tissue has been derived from photons migrating through these media (1). The diffusing photons enable us to noninvasively probe highly scattering materials and determine their average scattering and absorption properties (2, 3). Furthermore, the diffusing photons can also be utilized in imaging objects such as tumors hidden in turbid media (4-7). We present an analytic solution for the scattering of diffuse photon density waves (DPDWs) from spherical inhomogeneities embedded in an otherwise homogeneous medium and apply it to object imaging.The occurrence of DPDWs has been described in detail (8,9). In general, these waves arise when an intensity-modulated source oflight is introduced into a highly scattering or diffusive medium. Microscopically, individual photons undergo a random walk within the medium. Collectively, a wave of photon density is produced that propagates spherically outward from the source. These waves have a well-defined phase and amplitude at every point in the diffusive medium. When a localized heterogeneity is embedded in the medium, the spherical wave is distorted. The degree of distortion is determined by object characteristics (such as its position, shape, size, and scattering) and absorption properties.Since the Helmholtz equation is known to describe the transport of DPDWs in a piecewise homogeneous media (9, 10), we expect that an exact solution exists for the scattering of DPDWs by spherical objects. The solutions will be similar to, and simpler than, the theory of Mie scattering (11) often used in optics.We derive the analytic solution ofthe Helmholtz equation for a piecewise homogeneous system consisting of a spherical object composed of one highly scattering medium embedded in a second highly scattering medium of infinite spatial extent. This solution is easily extended to semiinfinite media by using the extrapolated zero boundary condition (2, 12, 13). The analytic solution is compared with experimental data to assess the theory's predictive power, and a simple inverse localization algorithm is demonstrated to determine the size and location of a spherical object. Finally, the theory is extended to include more complex problems in imaging. THEORYThe incoherent transport of photons in a highly scattering medium is generally described by a transport equation (11,13). In most m...

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“…3 Since then, this technique was used for our mathematical models and computer simulation for NIR transport in tissue. 4,5 The basic concept of analyzing the NIR data obtained from the tissue is exactly the same concept as the \Systems Identi¯cation Theory", which has been used in the identi¯cation of engineering systems' behavior for years. In the traditional system identi¯cation technique, the system to be analyzed is treated as a \black box", and the system to be analyzed by NIR spectroscopy is human (or animal) body or organs.…”

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confidence: 99%

Britton Chance's lab and thereafter: From NIR spectroscopy to molecular sensing via nanotechnology

Kang

2014

J. Innov. Opt. Health Sci.

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I was fortunate to work with/for Dr Britton Chance as his postdoctoral fellow, in the Biochemistry and Biophysics Department at the University of Pennsylvania, between August 1991 and January 1994. As anyone who worked for him, I had a sufficient dosage of "Britton Chance" over the years. Initially, to me, I felt that he was someone who was above regular people and far away to reach. Then I became to know him as a person, who was simple and complicated at the same time, with a persistent pursuit for his life interests, i.e., the advancement in science related to human health. As far as it goes to science (and perhaps with sailing), he had few boundary: He communicated with any age group, any one from any country with any cultural background. Any scientists were welcomed to his lab, his own house, and even his boat. He was happy with minimal material things. He kept his friendship faithfully. From him, I came to know how much one person can actually do during a life time. I am very grateful that I got to know him during my life path. In this paper, I list some of my experiences with him scientifically and also how and what I learned from him impacted my research and personal life.

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<title>Application of near-field interference of phase-modulated spectroscopy for detection of absorbers: theoretical prediction of phase shift with respect to the location of the absorber by using a probabilistic-numerical technique, the B-W-K method</title>

Cited by 6 publications

References 13 publications

Preliminary evaluation of dual wavelength phased array imaging on neonatal brain function

Preliminary evaluation of dual wavelength phased array imaging on neonatal brain function

Scattering of diffuse photon density waves by spherical inhomogeneities within turbid media: analytic solution and applications.

Britton Chance's lab and thereafter: From NIR spectroscopy to molecular sensing via nanotechnology

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