Theoretical and experimental studies of the propagation of modulation depth of the detected optical signal from an ultrasound zone

Abstract

Because it has the advantages of optical contrast and ultrasonic resolution, the ultrasound-modulated optical tomography becomes a new and promising method for biomedical imaging. The propagation of the light modulated by ultrasound in the tissue plays an important role in this new technique. We already proved that the modulated depth of the modulated light (Identical Modulated Depth, ignoring the background diffused light) was dependent on optical and ultrasonic properties of tissue within the ultrasound zoom, and didn't change in the propagation in the recent research. However, the modulation depth detected at the surface in experiment (Real Modulated Depth) differs from the Identical Modulated Depth, which includes the background diffused light. In Diffuse theory and experiments it is shown that the Real Modulated Depth is dependent on the propagation process of the diffused light. The relations to the Real Modulated Depth contributed by the tissue thickness, optical properties, etc. are figured out in this paper. So the Real Modulated Depth detected in the experiments should be transformed into the Identical Modulated Depth (a dominant parameter to imaging) by a set of iterated algorithm decoding. All these should contribute to the practical applications of ultrasound-modulated optical tomography.

Effect of apertures in ultrasound-modulated optical tomography with photomultiplier tube

“…I dc decreased and M grown with the PMT away the optic axis (along the y axis) as expected. properties of media in the ultrasonic focal zone not out of the ultrasonic focal zone [7][8][9] . So it is a key imaging factor in UOT.…”