PMC

Proportion of artificial stones containing fractures after exposure to 60,000 bursts as a function of focal pressure amplitude. At each pressure level, n = 3 stones were tested.

Images of uric acid (a), struvite (b), COM (c), and cystine (d) stones. The top images show the stone before 170-kHz burst wave exposure, and the bottom shows after treatment. The scale bars in (d) are 1 cm. All images have identical scales.

Photographic sequence of an artificial stone during exposure to 170 kHz bursts with p_f = 6.5 MPa over 8 minutes. Ultrasound (US) burst waves are incident on the stone from the left. The photograph to the right shows the fragments generated after 8 minutes of exposure. The scale bar is 1 cm.

Size distribution of fragments post-exposure measured by serial sieving of fragments. The left 4 groups show the size distribution of fragments for natural stones treated with 170 kHz bursts, while the right 3 groups show the size distribution of artificial stones treated with 170 kHz, 285 kHz, and 800 kHz bursts. All measurements are mean values for stones treated in each category. COM = calcium oxalate monohydrate.

Photographs of fractures (top) and fragments (bottom) generated for stones treated with 170 kHz (a), 285 kHz (b), and 800 kHz (c) bursts with similar peak pressure amplitude applied to the stone. Increased ultrasound frequency resulted in stone surface fractures closer together and decreased fragment size. Bursts were incident from the left side of the stone in each of the photographs. The scale bars for the top and bottom rows are both 1 cm.
SWL = Shock Wave Lithotripsy
BWL = Burst Wave Lithotripsy
COM = Calcium Oxalate Monohydrate

Modeled focal pressure waveforms for a lithotripsy shock wave (a) and ultrasound burst wave (b). The waveform in (a) approximates the shock from a Dornier HM3 lithotripter, while the burst wave in (b) corresponds with the highest pressure amplitude (p_a = 6.5 MPa) applied in this study. The experimental setup for exposure of stones to burst waves is shown in (c). A focused ultrasound transducer was placed in water tank, and the stone was aligned with the focus using a motorized 3-axis positioning system. The transducer was driven by an amplifier to expose the stone to ultrasound bursts. Fragments were collected in a small container positioned below the stone.