Indumathi J

Singh M.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Novel Optical Systems Design and Optimization XII

Surface backscattering profiles from a human forearm and transmission profiles through a human thumb, of red and near-infrared lasers, were determined. For the preparation of tissue-equivalent phantoms, white paraffin wax mixed with various wax color pigments were used. The surface reflectance profiles of a human forearm were matched with that of the phantom by mixing color pigments in various proportions. The reconstructed surface reflectance image of the phantom prepared by this procedure was similar to that of the human forearm. The transmission tomogram of the human thumb was obtained in fan-beam configuration by a near-infrared laser tomography system. Based on the horizontal scan of this tomogram, a two-layered phantom was made. The color composition of the phantom was so adjusted that its horizontal scan was matched with that of the thumb tomogram. The phantoms of complex tissues, prepared by this procedure, could be used for evaluation and calibration of new optical diagnostic imaging techniques.

IEEE Transactions on Biomedical Engineering

Laser backscattering and transillumination imaging of human tissues and their equivalent phantoms

The normalised back-scattered intensity (NBI) profiles at various locations on the forearms of ten human subjects were obtained by moving the multi-probe of a laser reflectometer. The statistical analysis of the NBI data showed that the variation in the NBI was significantly higher at the ulnar region compared with that at other regions. For determination of the scattering (μs) and absorption (μa) coefficients and the anisotropy parameter g at each location on the forearm, these profiles were matched with the NBI profiles simulated by a Monte Carlo procedure (X0.992). For the reconstruction of images of variation of these parameters, the averaged values of μa, μs and g at all locations on the forearms of the subjects were determined. The absorption coefficient had a minimum (1.92 cm-1) and maximum (2.21 cm-1) at the wrist and the lateral region of the forearm, respectively. The scattering coefficient had a maximum (194 cm-1) at the medial side and near the elbow, and a minimum (186 cm-1) at the lateral side of the forearm. Similar changes in the anisotropy parameter were also observed. By interpolation of the data of each parameter on a 100 × 100 image matrix and after median filtering, colour-coded images of the variation in the optical parameters were constructed. These images could be useful for diagnostic and therapeutic applications of lasers.

Medical and Biological Engineering and Computing

Non-invasive imaging of optical parameters of biological tissues

Laser back-scattered radiation from a human forearm is affected by the compositional variation in tissues and was imaged by a reflectance imaging system. The measurement probe consisted of one input fibre and one output fibre, separated by a distance of 0.3 cm. The diffuse reflectance data were collected by placing the probe on the forearm. By interpolation and median filtering of these data, the colour-coded reflectance images of the forearms of ten subjects were reconstructed. For comparative analysis of the mean reflectance, the forearm area was divided into ten regions. The mean normalised back-scattered intensity (NBI) near the ulnar region of the wrist was 4.76±0.24% and was significantly higher (p<0.0005) compared with that at other regions, which varied from 3.49±0.17% to 4.43±0.14%. Tissue-equivalent phantoms of these, required for the clinical assessment of optical techniques, were constructed using various combinations of paraffin wax and dyes. The matching of the NBI images of these stable and inexpensive phantoms with those of the forearms of the respective subjects showed the similarity of their optical parameters.

Laser reflectance imaging of human forearms and their tissue-equivalent phantoms

IEEE Transactions on Medical Imaging

Three-dimensional optical tomographic imaging of breast in a human subject

Laser backscattered radiations from tissue phantoms and human forearms are measured by a reflectance imager. Laser radiations are guided by an optical fibre, and the backscattered radiations are collected by three optical fibres in the measurement probe assembly, placed at distances of 2 mm, 4 mm and 6 mm from the input fibre. By placing the measurement probe on the phantom or tissue surface and matching the outline on the computer monitor, the reflectance data from the organ or the phantom are collected. These data, after digitization, interpolation and filtering, are colour coded and displayed on the computer monitor. Using this imaging procedure, the abnormalities embedded at different depths in the phantoms are located. The structural changes due to colour, composition and blood flow in the multi-layer of human forearms of various subjects are qualitatively shown in reflectance images obtained by this procedure.Laser backscattered radiations from tissue phantoms and human forearms are measured by a reflectance imager. Laser radiations are guided by an optical fibre, and the backscattered radiations are collected by three optical fibres in the measurement probe assembly, placed at distances of 2 mm, 4 mm and 6 mm from the input fibre. By placing the measurement probe on the phantom or tissue surface and matching the outline on the computer monitor, the reflectance data from the organ or the phantom are collected. These data, after digitisation, interpolation and filtering, are colour coded and displayed on the computer monitor. Using this imaging procedure, the abnormalities embedded at different depths in the phantoms are located. The structural changes due to colour, composition and blood flow in the multi-layer of human forearms of various subjects are qualitatively shown in reflectance images obtained by this procedure.

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