Zvi Kotler

Bio: Zvi Kotler is an academic researcher from Israel Atomic Energy Commission. The author has contributed to research in topics: Imaging phantom & Chalcogenide glass. The author has an hindex of 3, co-authored 6 publications receiving 125 citations.

Detection of inhomogeneities with ultrasound tagging of light

Abstract: Ultrasound modulated light for optical tomography is very useful, since it can provide three-dimensional data with minimal mathematical processing. Although several experimental studies have shown the potential of this method, the link between the ultrasound location and the modulated signal intensity at the detector is not yet fully understood. We derive an analytical formula relating the position of the ultrasound transducer and the optical signal at the detector. We also derive an expression for the signal-to-shot-noise ratio as a function of the transducer position. We show that in certain conditions this ratio is only slowly decreasing as a function of the light penetration depth, which makes this technique attractive for optical tomography.

Metabolism monitoring of body organs

Abstract: Method and apparatus for determining the oxygenation level of hemoglobin in a probed region of the human body. A probed region of the body is irradiated with diffuse light, the frequency of which is shifted with ultrasound focused at the probed region. The relation between the two states of the oxygenation of the hemoglobin is determined by the light absorption at the focal region of the ultrasound. The blood volume may be monitored by irradiating the probed region with light at the isosbestic point.

Method and apparatus for imaging absorbing objects in a scattering medium

Abstract: A method and processing device are presented for reconstructing an absorption and/or scattering image of a region of interest inside a scattering medium. A mathematical model is provided being representative of a relation between the distribution of the intensity and phase of electromagnetic radiation components scattered from a medium and a certain attenuation factor, which is function of spatial variations of scattering and absorption coefficients of the medium. The mathematical is used for processing a map of distribution of the intensity of electromagnetic radiation components scattered from known locations within the region of interest, thereby producing a halftone pattern of the region of interest.

Chalcogenide three-dimensional photonic structures

Abstract: AsSeTe/AsSe chalcogenide glasses are photosensitive materials with large refractive index. These properties make these glasses suitable for the fabrication of photonic crystals, waveguide components and MOEMS. We present in this article fabrication of 3D photonic crystals, composed from AsSeTe and air, with sub-micron feature size. The method of fabrication is relatively simple and cheap using only vapor deposition and optical holographic lithography. The interferometric alignment allows to eliminate requirement for a mask aligner.

Ultrasonic probing of the banana photon distribution in turbid media

Abstract: Probing photon density in diffusive media is very important in order to model and understand their propagation. It is possible to detect photons outside the medium, but their non-invasive detection inside it is still an unsolved problem. An elegant, semi-invasive approach to perform this task is to scan a small absorbing sphere inside the turbid medium and measure the light outside the sample when the sphere is present and when it is not. However this method requires the medium to be liquid and such a procedure cannot be performed in the case of biological tissues. Ultrasound tagging of light has been introduced initially for transillumination imaging in turbid media, and then extended to the case of reflection imaging. Here we present results showing that it is possible to map the photon density inside solid turbid media by locally tagging photons using an ultrasonic field. We experimentally retrieve the well-known banana-shaped photons distribution when the source and the detectors are in a back-scattering configuration, using a gel-based homogeneous phantom. We also present experiments where hemoglobin has been introduced inside the gel. By fitting the experimental results with the theoretical formula, we are able to quantitatively retrieve the amount of hemoglobin introduced inside the gel, not only from data obtained by scanning the ultrasound waist inside the phantom, the in put and output fibers staying fixed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Ultrasound-mediated biophotonic imaging: A review of acousto-optical tomography and photo-acoustic tomography

Abstract: This article reviews two types of ultrasound-mediated biophotonic imaging–acousto-optical tomography (AOT, also called ultrasound-modulated optical tomography) and photo-acoustic tomography (PAT, also called opto-acoustic or thermo-acoustic tomography)–both of which are based on non-ionizing optical and ultrasonic waves. The goal of these technologies is to combine the contrast advantage of the optical properties and the resolution advantage of ultrasound. In these two technologies, the imaging contrast is based primarily on the optical properties of biological tissues, and the imaging resolution is based primarily on the ultrasonic waves that either are provided externally or produced internally, within the biological tissues. In fact, ultrasonic mediation overcomes both the resolution disadvantage of pure optical imaging in thick tissues and the contrast and speckle disadvantages of pure ultrasonic imaging. In our discussion of AOT, the relationship between modulation depth and acoustic amplitude is clarified. Potential clinical applications of ultrasound-mediated biophotonic imaging include early cancer detection, functional imaging, and molecular imaging.

Apparatus and method for non-invasive and minimally-invasive sensing of parameters relating to blood

Abstract: Medical diagnostic system, apparatus and methods are disclosed. Optical transmitters generate radiation-containing photons having a specific interaction with at least one target chromophore in a target structure, preferably a blood vessel such as the interior jugular vein. The optical transmitters transmit the radiation into at least a first area including a substantial portion of the target structure and into a second area not including a substantial portion of the target structure. Optical receivers detect a portion radiation scattered from at least the first area and the second area. A processor estimates oxygenation, pH or cardiac output based on the scattered radiation detected from the first area, and the scattered radiation from the second area.

Photoacoustic assay and imaging system

Abstract: A method for assaying a component of a localized region of interest in a body comprising: illuminating the region with at least one pulse of radiation having a wavelength at which the radiation is absorbed by the component to generate a change in an acoustic property of the region; transmitting ultrasound so that it is incident on the region; measuring at least one effect of the change on the incident ultrasound; using the measured at least one effect to determine an absorption coefficient for the radiation in the region; and using the determined absorption coefficient to determine concentration of the component in the region.

Apparatus and method for non-invasive and minimally-invasive sensing of venous oxygen saturation and pH levels

Abstract: Medical diagnostic apparatus and methods are disclosed. Ultrasound radiation pressure selectively modulates a target area within a body. One or more pulses of radiation containing temporally correlated groups of photons are generated. The photons are characterized by two or more different wavelengths that are selected to have specific interaction with a target chromophore. The two or more different wavelengths are also selected to have substantially similar scattering cross-sections and anisotropy parameters in the target and its surroundings. The pulses of radiation are injected into the body proximate the target area being modulated by the radiation pressure field. Photon groups at each of the different wavelengths that are backscattered from the target area are detected in temporal coincidence. Time-gated background-free amplification of the return signal is used to exclude photons which could not by virtue of their arrival time have interacted with the radiation-pressure-modulated target. Photon groups are selected with a modulation component at the modulation frequency of the radiation pressure modulation field, or at a harmonic of the modulation frequency. From the arrival rate of the detected temporally correlated photon pairs or multiplets, chemical information about the target area, such as an oxygenation or pH level can be inferred. Cardiac output may be computed from measurements of venous and/or arterial oxygenation using this technique.

Progress in optical waveguides fabricated from chalcogenide glasses

Abstract: We review the fabrication processes and properties of waveguides that have been made from chalcogenide glasses including highly nonlinear waveguides developed for all-optical processing.