M. Kumaravel

Laser Reflectance Imaging of Human Chest for Localization of Internal Organs

The normalized backscattered intensity (NBI) profiles at various locations of human thorax by multiprobe laser reflectometer are obtained. These data after digitization, interpolation, and filtering are color-coded and displayed as images on the outline of the human thorax. For optical characterization of tissues in terms of their parameters, scattering and absorption coefficients and the anisotropy parameter (g) are obtained by matching the measured NBI profile with that as obtained by Monte Carlo simulation procedure. Corresponding to the variation of the NBI over the various regions, the optical parameters show their respective changes. The maximum absorption and minimum scattering coefficients are observed at the areola, clavicle, sternum, scapula, and vertebral column. The minimum absorption and maximum scattering coefficients are observed at the pectoralis major of chest and rectus abdominis of abdomen regions, as compared to the other regions, attributed to their tissue compositional variations. To visualize the various tissues in lower regions of the thorax, the color-coded scheme of the NBI variation, as measured by the third fiber, is further expanded. By this procedure, the outlines of the heart and lungs, as detected through intercostals regions, are observed, which is in good agreement with that as determined by the chest radiograph of the same subject taken in PA position. Similarly the lower sections of the liver and stomach, due to their distinct optical parameters, are also observed.

Non-Invasive Imaging and Characterization of Human Thorax Tissues by Non-Contact Scanning Multi-Probe Laser Reflectometry and Monte Carlo Simulation

The normalized back-scattered intensity (NBI) profiles at various locations on the human thorax of a subject were obtained by multi-probe laser reflectometer. The laser radiations are guided by an optical fiber onto the human thorax tissues and the backscattered radiations are collected by three optical fibers placed at distance of 2 mm, 4 mm and 6 mm from the input fiber. The data collection of the human thorax tissue is carried out using an automatic non-contact scanning system controlled by the personal computer. The data after digitization, interpolation and filtering, are color-coded and displayed on the outline of the human thorax. These NBI pattern vary depending on the muscular, anatomical and vascular compositions and also on percentage of fat composition at various locations. For optical characterization the optical parameters, scattering (mus) and absorption (mua) coefficients and the anisotropy parameter (g) at each location on the human thorax, by matching of reflectance profiles with that as simulated by a Monte Carlo simulation (MCS) procedure were determined. The point-to-point variations of the optical parameters and NBI variations at various regions of the human thorax tissues are studied

Laser Reflectance Imaging of Curved Tissue-equivalent Phantoms

The surface backscattered radiations of curved tissue-equivalent phantom are measured using miniature multi-probe laser reflectometer imaging system. Phantom models are prepared using paraffin wax mixed with wax colors and their optical parameters are determined by comparing measured backscattered profile with that of Monte Carlo simulation procedure. Abnormalities with optical parameters 5% less than the normal phantom are introduced at various depths in different locations. These phantoms are scanned using miniature laser reflectometer scanner. The acquired data after digitizing, interpolation and filtering is represented as 3-D color coded images which show the location and size of the abnormalities

Optical Characterization of Internal Organs in-situ by He-Ne Laser Light Reflectometry

The measurement of He-Ne laser light reflectance of various internal organs in-situ, to obtain the absorption and scattering parameters, is carried out. The laser reflectometer is consisting of an optical fibre- Y guide probe. Through one arm of this the laser beam is guided to the various internal organs of the anasthetized mongrel dogs. The reflected radiations from the tissue site are collected by another arm of the probe and detected by HAD-1000A photodetector—amplifier assembly. The results show that the reflectance of the internal organs varies over a large range and is the maximum at the arch of aorta and the minimum at the spleen. The optical parameter, the scattering and absorption coefficients, calculated based on the above data show variation related to their tissue compositions.