Characterization of blood flow rate in dental pulp by speckle patterns of backscattered light from an in vivo tooth.

Experimental data on the hemodynamics of dental pulp at different stages of caries treatment are given. Observations of speckle patterns in backscattered laser light are used as a measurement method to qualitatively characterize changes in blood flow rate through the dental pulp. The measurements were made by the author-designed experimental setup. Theoretical estimations showed that stationary reflected light from an in vivo tooth contains a negligibly small information body on changes in the pulpal blood flow due to the shadowing of the pulp by optically thick enamel and dentin. Therefore, the temporal variations in the speckle patterns are the only possible way that can provide monitoring of blood conditions in the pulp by using backscattered light. Various statistical characteristics of the random reflected light fields are studied as indicators of blood flow rate changes. There were selected five statistical parameters of backscattered speckle images that give self-consistent data on these changes. The parameters include four combinations of integrals of the Fourier transforms of the observed temporal variations as well as the speckle image contrast. The selected parameters are shown to qualitatively agree with general considerations on the effects of reduced or increased blood flow rates on the selected integral quantities.

Estimation of blood microcirculation in integuments by non-invasive speckle-optical method under the photodynamic action.

In studies on animals (rats, rabbits) an experimental technique for estimation of microhemocirculation parameters of tissue under treatment has been developed. This technique has been used to compare the changes of speckle-optical parameters of skin microhemodynamics in laser-irradiated and light-isolated areas in the course of photodynamic therapy. Strong correlation between efficiency of tissue response and injection-photoirradiation time interval has been established. The results obtained are confirmed by the data of microhemodynamics estimation in the course of photodynamic therapy by the method of intravital microscopy. The defined ways of modification of the speckle-optical module will make it possible to optimize the conditions of parameters registration taking into account the object features and to improve informativity and sensitivity of the method.