Work: Experimental investigation of an enhancement of efficiency of thermal and mechanical effects of powerful focused ultrasound beam on a biological tissue like mediums due to its nonlinearity. Moscow State University.

Date of birth:   November 26, 1977.

Place of birth: Russia, Moscow region.

Education: Graduated from Physics Department of Moscow State University in 2000, MS in Physics with excellence.

Main results: It is known that HIFU is used in therapeutic and diagnostic applications of ultrasound in medicine. Thermal treatment of cancer tumor by means of dissipation of ultrasound energy is one of the important application. The phenomenon of enhancement of heat deposition into the gelatin phantom due to nonlinear distortion of acoustic wave has been studied experimentally. In the experiment several sets of pulsed periodic regimes of ultrasound, with the same mean power but different amplitudes and duty cycles, were used. It was observed that than the amplitude was higher, than the nonlinear distortion in focal region was more pronounced and, as a result, the heat deposition in this region was more efficient. In linear medium the heating would be the same. Another application of ultrasound in medicine is a shear wave elasticity imaging of cancer tumor. The efficiency of a shear stress generation in tissue mimicking phantom was under the investigation. In the experiment the shear wave has been excited in gelatin sample placed in the focal region of powerful focused ultrasound beam working in pulsed regimes with a same total power of pulses but different amplitudes and durations. Temporal profiles of the shear wave have been registered optically at different distances from the focal region. Due to nonlinear distortion of acoustic waveform in focal region the amplitude of shear stresses induced by high amplitude short pulse was higher that in the case of longer one with lower amplitude.

Main publications:

1. Sapozhnikov, O.A. and Sinilo, T.V., Enhancement of Heat Deposition Generated by Powerful Ultrasound Beam in Liquid Medium due to Presence of Shocks in the Waveform. Izvestiy Akademii Nauk (seriya fizicheskaya), 1998, 62(12), 2371-2374 (in Russian).
2. O.A. Sapozhnikov, T.V. Sinilo, and Y.A. Pishchalnikov. Experimental Demonstration of Enhancement of Heat Deposition in a Focused Ultrasound Beam with Shocks. Nonlinear Acoustics at the Turn of the Millennium: 15th International Symposium on Nonlinear Acoustics, Gottingen, Germany 1999, p. 483-486.
3. O.A. Sapozhnikov, T.V. Sinilo, and Yu.A. Pishchalnikov. Excitation of Shear Wave in Gelatin by a Focused Sawtooth Wave. Nonlinear Acoustics at the Turn of the Millennium: 15th International Symposium on Nonlinear Acoustics, Gottingen, Germany 1999, p. 203-206.
4. Sapozhnikov, O.A., and Sinilo, T.V. Numerical Investigation of the Concave Transducer's Field by Means of Matched Expansions Method. Proceedings of the X Session of Russian Acoustical Society, v. 1, p. 179-182, Moscow (in Russian, and there is an english version, PDF, 124K).