Spatial resolution, measuring time, and fast visualization of hidden deep phantoms in diffusion optical tomography of extended scattering objects

摘要

We present the results of testing a prototype of an optical tomograph (a continuous-wave diode laser with a wavelength of 775 nm and a power of 15-20 mW) and fast algorithms for the I reconstruction of the internal structure of extended (with linear sizes up to 150 mm) strongly scattering objects. Model experiments (with absorption coefficients of 0.005-0.015 and scattering coefficients of 1.4 mm(-1)) have demonstrated that the distributions of the probability that detected photons pass through such objects (projections) can he described in terms of the coefficient of relative trajectory lengthening, whose value is independent of the arrangement of a light source and a detector. This experimental finding, confirmed by Monte Carlo numerical simulations, allows a simple scaling of projections in the case when the distance between the light source and the detector changes, thus providing an opportunity to implement fast real-time approximate statistical nonlinear algorithms for the solution of inverse and direct problems of optical tomography. Experimental testing of the prototype and the developed algorithms has shown that, for a model object with a diameter of 140 mm within the studied range of optical parameters, the coefficient of relative trajectory lengthening ranges from 1.2 to 1.9, and the reconstruction of an image of a strongly absorbing inclusion with a diameter of 1-2 mm requires no more than 0.5-1 min. [References: 47]