title: Nonlinear Effects in Ultrasound Fields of Diagnostic-type Transducers Used for Kidney Stone Propulsion: Characterization in Water.
abstract: Newer imaging and therapeutic ultrasound technologies require higherin situpressure levels compared to conventional diagnostic values. One example is the recently developed use of focused ultrasonic radiation force to move kidney stones and residual fragments out of the urinary collecting system. A commercial diagnostic 2.3 MHz C5-2 array probe is used to deliver the acoustic pushing pulses. The probe comprises 128 elements equally spaced at the 55 mm long convex cylindrical surface with 38 mm radius of curvature. The efficacy of the treatment can be increased by using higher transducer output to provide stronger pushing force; however, nonlinear acoustic saturation effect can be a limiting factor. In this work nonlinear propagation effects were analyzed for the C5-2 transducer using a combined measurement and modeling approach. Simulations were based on the 3D Westervelt equation; the boundary condition was set to match low power pressure beam scans. Focal waveforms simulated for increased output power levels were compared with the fiber-optic hydrophone measurements and were found in good agreement. It was shown that saturation effects do limit the acoustic pressure in the focal region of the transducer. This work has application to standard diagnostic probes and imaging.
authors.affiliation: Laboratoire de Mécanique des Fluides et d'Acoustique, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France; Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation.
authors.forename: M
authors.initials: M
authors.lastname: Karzova
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40 Street, Seattle, WA 98105, USA.
authors.forename: B
authors.initials: B
authors.lastname: Cunitz
authors.affiliation: Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation.
authors.forename: P
authors.initials: P
authors.lastname: Yuldashev
authors.affiliation: Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation.
authors.forename: Y
authors.initials: Y
authors.lastname: Andriyakhina
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40 Street, Seattle, WA 98105, USA.
authors.forename: W
authors.initials: W
authors.lastname: Kreider
authors.affiliation: Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation; Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40 Street, Seattle, WA 98105, USA.
authors.forename: O
authors.initials: O
authors.lastname: Sapozhnikov
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40 Street, Seattle, WA 98105, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bailey
authors.affiliation: Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow, Russian Federation; Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 NE 40 Street, Seattle, WA 98105, USA.
authors.forename: V
authors.initials: V
authors.lastname: Khokhlova