Quantitative measurement of focused ultrasound pressure field using subtraction shadowgraph

In this study, the measurement of focused ultrasound pressure field by the subtraction shadowgraph method was investigated. Conventional shadowgraph is known as a fast, noninvasive, but qualitative method of ultrasound pressure field measurement. On the other hand, the subtraction shadowgraph method in this paper can provide quantitative projection images, from which the ultrasound pressure field can be reconstructed. Subtraction shadowgraph images of a focused ultrasound field were obtained, it was converted to the projection of the refractory distribution, and the focused ultrasound pressure field was reconstructed from the projection by computed tomography algorithm. The result was compared with that of hydrophone measurement, and successful reconstruction of the axi-symmetric pressure distribution of the focal field was confirmed in both lateral and axial cross sections.