Plasma formation in holmium:YAG laser lithotripsy.

Objectives: During holmium:yttrium-aluminum-garnet (holmium:YAG) laser lithotripsy to break urinary stones, urologists frequently see flashes of light. As infrared laser pulses are invisible, what is the source of light? Here we studied the origin, characteristics, and some effects of flashes of light in laser lithotripsy.

Methods: Ultrahigh-speed video-microscopy was used to record single laser pulses at 0.

High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone.

Ultra-high-speed video microscopy and numerical modeling were used to assess the dynamics of microbubbles at the surface of urinary stones. Lipid-shell microbubbles designed to accumulate on stone surfaces were driven by bursts of ultrasound in the sub-MHz range with pressure amplitudes on the order of 1 MPa. Microbubbles were observed to undergo repeated cycles of expansion and violent collapse.

Comment on "Effect of liquid temperature on sonoluminescence".

It has been suggested that bubble-wall velocities cannot exceed the sound speed in the liquid at the bubble wall [K. Yasui, Phys. Rev.

Experimental observations and numerical modeling of lipid-shell microbubbles with calcium-adhering moieties for minimally-invasive treatment of urinary stones.

A novel treatment modality incorporating calcium-adhering microbubbles has recently entered human clinical trials as a new minimally-invasive approach to treat urinary stones. In this treatment method, lipid-shell gas-core microbubbles can be introduced into the urinary tract through a catheter. Lipid moities with calcium-adherance properties incorporated into the lipid shell facilitate binding to stones.

Outcomes of the collapse of a large bubble in water at high ambient pressures.

Presented here are observations of the outcomes of the collapses of large single bubbles in H_{2}O and D_{2}O at high ambient pressures. Experiments were carried out in a high-pressure spherical resonator at ambient pressures of up to 30 MPa and acoustic pressures up to 35 MPa. Monitoring of the collapse events and their outcomes was accomplished using multiframe high-speed photography.

Intense cavitation at extreme static pressure.

Cavitation is usually performed at hydrostatic pressures at or near 0.1 MPa. Higher static pressure produces more intense cavitation, but requires an apparatus that can build high amplitude acoustic waves with rarefactions exceeding the cavitation threshold.

Cavitation-induced streaming in shock wave lithotripsy.

Cavitation generated by lithotripter shock waves (SWs) in non-degassed water was studied using a 60 frames-per-second camcorder-recording the migration of microbubbles over successive SWs. Lithotripter SWs were produced using a Dornier DoLi-50 electromagnetic lithotripter at 0.5 and 2 Hz pulse repetition frequency (PRF).

Evaluation of the LithoGold LG-380 lithotripter: in vitro acoustic characterization and assessment of renal injury in the pig model.

Purpose: Conduct a laboratory evaluation of a novel low-pressure, broad focal zone electrohydraulic lithotripter (TRT LG-380).

Methods: Mapping of the acoustic field of the LG-380, along with a Dornier HM3, a Storz Modulith SLX, and a XiXin CS2012 (XX-ES) lithotripter was performed using a fiberoptic hydrophone. A pig model was used to assess renal response to 3000 shockwaves (SW) administered by a multistep power ramping protocol at 60 SW/min, and when animals were treated at the maximum power setting at 120 SW/min.

Temporally and spatially resolved imaging of laser-nucleated bubble cloud sonoluminescence.

Imaging techniques have been used to capture the temporal and spatial evolution of light emissions from collapsing bubble clouds at high static pressures. Emission events lasting up to 70 ns with peak diameters nearing 1 mm have been observed. Observations of the cloud evolution before and after emission events have been made.

Size and location of defects at the coupling interface affect lithotripter performance.

Unlabelled: Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? In shock wave lithotripsy air pockets tend to get caught between the therapy head of the lithotripter and the skin of the patient. Defects at the coupling interface hinder the transmission of shock wave energy into the body, reducing the effectiveness of treatment.

Fragility of brushite stones in shock wave lithotripsy: absence of correlation with computerized tomography visible structure.

Purpose: Brushite stones were imaged in vitro and then broken with shock wave lithotripsy to assess whether stone fragility correlates with internal stone structure visible on helical computerized tomography.

Materials And Methods: A total of 52 brushite calculi were scanned by micro computerized tomography, weighed, hydrated and placed in a radiological phantom. Stones were scanned using a Philips® Brilliance iCT 256 system and images were evaluated for the visibility of internal structural features.

Evaluation of shock wave lithotripsy injury in the pig using a narrow focal zone lithotriptor.

Unlabelled: What's known on the subject? and What does the study add? Of all the SW lithotriptors manufactured to date, more research studies have been conducted on and more is known about the injury (both description of injury and how to manipulate injury size) produced by the Dornier HM-3 than any other machine. From this information have come suggestions for treatment protocols to reduce shock wave (SW)-induced injury for use in stone clinics. By contrast, much less is known about the injury produced by narrow-focus and high-pressure lithotriptors like the Storz Modulith SLX.

Bubble proliferation in the cavitation field of a shock wave lithotripter.

Lithotripter shock waves (SWs) generated in non-degassed water at 0.5 and 2 Hz pulse repetition frequency (PRF) were characterized using a fiber-optic hydrophone. High-speed imaging captured the inertial growth-collapse-rebound cycle of cavitation bubbles, and continuous recording with a 60 fps camcorder was used to track bubble proliferation over successive SWs.

Assessment of renal injury with a clinical dual head lithotriptor delivering 240 shock waves per minute.

Purpose: Lithotriptors with 2 treatment heads deliver shock waves along separate paths. Firing 1 head and then the other in alternating mode has been suggested as a strategy to treat stones twice as rapidly as with conventional shock wave lithotripsy. Because the shock wave rate is known to have a role in shock wave lithotripsy induced injury, and given that treatment using 2 separate shock wave sources exposes more renal tissue to shock wave energy than treatment with a conventional lithotriptor, we assessed renal trauma in pigs following treatment at rapid rate (240 shock waves per minute and 120 shock waves per minute per head) using a Duet lithotriptor (Direx Medical Systems, Petach Tikva, Israel) fired in alternating mode.

Effect of firing rate on the performance of shock wave lithotriptors.

Objective: To determine the mechanism that underlies the effect of shock wave (SW) rate on the performance of clinical lithotripters.

Materials And Methods: The effect of firing rate on the pressure characteristics of SWs was assessed using a fibre-optic probe hydrophone (FOPH 500, RP Acoustics, Leutenbach, Germany). Shock waves were fired at slow (5-27 SW/min) and fast (100-120 SW/min) rates using a conventional high-pressure lithotriptor (DoLi-50, Dornier MedTech America, Inc.

Improved acoustic coupling for shock wave lithotripsy.

Previous in vitro studies of acoustic coupling in shock wave lithotripsy (SWL) have shown that air pockets trapped at the surface of the treatment head significantly reduce transmission of shock wave (SW) energy to the focal zone of the lithotripter, reducing the effectiveness of stone breakage. Since there are no reliable means to monitor the quality of coupling during SWL, we looked for a practical protocol to improve how coupling is achieved. In vitro studies were performed using a Dornier DoLi-50 lithotripter.

Independent assessment of a wide-focus, low-pressure electromagnetic lithotripter: absence of renal bioeffects in the pig.

Objective: To assess the renal injury response in a pig model treated with a clinical dose of shock waves (SWs) delivered at a slow rate (27 SW/min) using a novel wide focal zone (18 mm), low acoustic pressure (<20 MPa) electromagnetic lithotripter (Xi Xin-Eisenmenger, XX-ES; Xi Xin Medical Instruments Co. Ltd., Suzhou, PRC).

CT visible internal stone structure, but not Hounsfield unit value, of calcium oxalate monohydrate (COM) calculi predicts lithotripsy fragility in vitro.

Calcium oxalate monohydrate (COM) stones are often resistant to breakage using shock wave (SW) lithotripsy. It would be useful to identify by computed tomography (CT) those COM stones that are susceptible to SW's. For this study, 47 COM stones (4-10 mm in diameter) were scanned with micro CT to verify composition and also for assessment of heterogeneity (presence of pronounced lobulation, voids, or apatite inclusions) by blinded observers.

Dual-head lithotripsy in synchronous mode: acute effect on renal function and morphology in the pig.

Objective: To assess the effect of dual-head lithotripsy on renal function and morphology in a pig model of shockwave (SW) injury, as lithotripters with two shock heads are now available for treating patients, but little information is available with which to judge the safety of treatment with dual pulses.

Materials And Methods: A dual-head electrohydraulic lithotripter (Duet, Direx Corp., Natick, MA, USA) was used to treat the lower renal pole of anaesthetized pigs with a clinical dose of SWs (2400 dual SWs; 10 kidneys) delivered in synchronous mode, i.

Air pockets trapped during routine coupling in dry head lithotripsy can significantly decrease the delivery of shock wave energy.

Purpose: Current lithotriptors use a dry treatment head that must be coupled to the patient with gel or oil. We determined how the quality of coupling affects stone breakage under conditions that simulated patient treatment.

Materials And Methods: Experiments were performed with a Dornier (DoLi-50 electromagnetic lithotriptor.

Detection of significant variation in acoustic output of an electromagnetic lithotriptor.

Purpose: We describe the observation of significant instability in the output of an electromagnetic lithotriptor. This instability had a form that was not detected by routine assessment, but rather was observed only by collecting many consecutive shock waves in nonstop regimen.

Materials And Methods: A Dornier DoLi-50 lithotriptor used exclusively for basic research was tested and approved by the regional technician.

Why stones break better at slow shockwave rates than at fast rates: in vitro study with a research electrohydraulic lithotripter.

Background And Purpose: Stones break better when the rate of shockwave (SW) delivery is slowed. It has been hypothesized that the greater cavitation accompanying a fast rate shields pulse propagation, thus interfering with the delivery of SW energy to the stone. We tested this idea by correlating waveforms measured at the SW focus with cavitation viewed using high-speed imaging.

Cavitation selectively reduces the negative-pressure phase of lithotripter shock pulses.

Measurements using a fiber-optic probe hydrophone, high-speed camera, and B-mode ultrasound showed attenuation of the trailing negative-pressure phase of a lithotripter shock pulse under conditions that favor generation of cavitation bubbles, such as in water with a high content of dissolved gas or at high pulse repetition rate where more cavitation nuclei persisted between pulses. This cavitation-mediated attenuation of the acoustic pulse was also observed to increase with increasing amplitude of source discharge potential, such that the negative-pressure phase of the pulse can remain fixed in amplitude even with increasing source discharge potential.

Cavitation detection during shock-wave lithotripsy.

A system was built to detect cavitation in pig kidney during shock-wave lithotripsy (SWL) with a Dornier HM3 lithotripter. Active detection using echo on B-mode ultrasound, and passive cavitation detection using coincident signals on confocal orthogonal receivers, were used to interrogate the renal collecting system (urine) and the kidney parenchyma (tissue). Cavitation was detected in urine immediately upon shock-wave (SW) administration in urine or urine plus X-ray contrast agent but, in native tissue, cavitation required hundreds of SWs to initiate.