Scholars@Duke
Pei Zhong

Pei Zhong

Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science
Thomas Lord Department of Mechanical Engineering and Materials Science
pzhong@duke.edu
1103 Engineering Annex, Box 90300, Durham, NC 27708-0300
1103 Engineering Annex, Box 90300, Durham, NC 27708

Scholarly Works - Journal articles

Intra-Crater Bubble Expansion Drives the Fracture of Impacted Ureteral Artificial and Human Calcium Phosphate Stones in Laser Lithotripsy.

Journal article Lasers in surgery and medicine · May 2026 ObjectivesTo investigate the fracture mechanism of impacted ureteral stones during laser lithotripsy (LL).Materials and methodsImpacted 6 × 6 mm cylindrical BegoStone samples embedded in a hydrogel ureter model and a 100% calcium phosphat ... Full text Cite

Ejecta-Modulated Bubble Dynamics Play a Dominant Role in Stone Retropulsion.

Journal article Advanced science (Weinheim, Baden-Wurttemberg, Germany) · April 2026 Cavitation bubbles generated by laser absorption in liquids collapse violently, producing high-speed jets, toroidal bubbles, and shock waves that induce material erosion and object displacement. In laser lithotripsy, this phenomenon causes kidney stone mig ... Full text Cite

Thermal injury and treatment efficiency during thulium fiber laser lithotripsy: insights from an in vivo porcine model.

Journal article World J Urol · January 11, 2026 PURPOSE: To evaluate the risk of thermal injury and the treatment efficiency during thulium fiber laser (TFL) lithotripsy of renal and ureteral stone phantoms in an in vivo porcine model. METHODS: BegoStone phantoms were sequentially implanted and treated ... Full text Link to item Cite

Nanofluid-Enhanced Laser Lithotripsy Using Conducting Polymer Nanoparticles.

Journal article Adv Sci (Weinh) · December 2025 Urinary stone disease, characterized by the hard mineral deposits in the urinary tract, has seen a rising prevalence globally. This condition often leads to severe pain and requires medical intervention. Laser lithotripsy, a minimally invasive treatment, u ... Full text Open Access Link to item Cite

Optimizing Fragmentation while Minimizing Thermal Injury Risk with the Thulium Fiber Laser in Ureteral Stone Lithotripsy: An In Vitro Study.

Journal article J Endourol · July 2025 Objective: To optimize thulium fiber laser (TFL) settings for effective stone fragmentation although minimizing thermal injury in confined ureteral spaces using a three-dimensional ureter model. Materials and Methods: A hydrogel-based ureter model was main ... Full text Link to item Cite

Three-Dimensional Super-Resolution Passive Cavitation Mapping in Laser Lithotripsy.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · December 2024 Kidney stone disease is a major public health issue. By breaking stones with repeated laser irradiation, laser lithotripsy (LL) has become the main treatment for kidney stone disease. Laser-induced cavitation is closely associated with stone damage in LL. ... Full text Open Access Link to item Cite

Vapour bubbles produced by long-pulsed laser: a race between advection and phase transition.

Journal article Journal of fluid mechanics · November 2024 Vapor bubbles produced by long-pulsed laser often have complex non-spherical shapes that reflect some characteristics of the laser beam. The transition between two commonly observed shapes - namely, a rounded pear-like shape and an elongated conical shape ... Full text Open Access Cite

Editorial Comment.

Journal article J Urol · October 2024 Full text Link to item Cite

A model-based simulation framework for coupled acoustics, elastodynamics, and damage with application to nano-pulse lithotripsy

Journal article International Journal of Solids and Structures · March 1, 2024 We develop a model for solid objects surrounded by a fluid that accounts for the possibility of acoustic pressures giving rise to damage on the surface of the solid. The propagation of an acoustic pressure in the fluid domain is modeled by the acoustic wav ... Full text Open Access Cite

Exploring optimal settings for safe and effective thulium fibre laser lithotripsy in a kidney model.

Journal article BJU Int · February 2024 OBJECTIVES: To explore the optimal laser settings and treatment strategies for thulium fibre laser (TFL) lithotripsy, namely, those with the highest treatment efficiency, lowest thermal injury risk, and shortest procedure time. MATERIALS AND METHODS: An in ... Full text Open Access Link to item Cite

Shock waves generated by toroidal bubble collapse are imperative for kidney stone dusting during Holmium:YAG laser lithotripsy.

Journal article Ultrasonics sonochemistry · December 2023 Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy (LL) has been the treatment of choice for kidney stone disease for more than two decades, yet the mechanisms of action are not completely clear. Besides photothermal ablation, recent evidence sugge ... Full text Cite

In vitro investigation of stone ablation efficiency, char formation, spark generation, and damage mechanism produced by thulium fiber laser.

Journal article Urolithiasis · November 2, 2023 To investigate stone ablation characteristics of thulium fiber laser (TFL), BegoStone phantoms were spot-treated in water at various fiber tip-to-stone standoff distances (SDs, 0.5 ~ 2 mm) over a broad range of pulse energy (Ep, 0.2 ~ 2 J), frequency (F, 5 ... Full text Open Access Link to item Cite

In Pursuit of the Optimal Dusting Settings with the Thulium Fiber Laser: An In Vitro Assessment.

Journal article J Endourol · August 2023 Objective: Low energy and high frequency settings are used in stone dusting for holmium lasers. Such settings may not be optimal for thulium fiber laser (TFL). With the seemingly endless combination of settings, we aim to provide guidance to the practicing ... Full text Link to item Cite

Model-based simulations of pulsed laser ablation using an embedded finite element method.

Journal article International journal of heat and mass transfer · May 2023 A model of thermal ablation with application to multi-pulsed laser lithotripsy is presented. The approach is based on a one-sided Stefan-Signorini model for thermal ablation, and relies on a level-set function to represent the moving interface between the ... Full text Cite

Intercellular Calcium Waves and Permeability Change Induced by Vertically Deployed Surface Acoustic Waves in a Human Cerebral Microvascular Endothelial Cell Line (hCMEC/D3) Monolayer.

Journal article Ultrasound in medicine & biology · May 2023 ObjectiveThe ultrasound-mediated blood-brain barrier (BBB) opening with microbubbles has been widely employed, while recent studies also indicate the possibility that ultrasound alone can open the BBB through a direct mechanical effect. However, t ... Full text Cite

Dissimilar cavitation dynamics and damage patterns produced by parallel fiber alignment to the stone surface in holmium:yttrium aluminum garnet laser lithotripsy.

Journal article Physics of fluids (Woodbury, N.Y. : 1994) · March 2023 Recent studies indicate that cavitation may play a vital role in laser lithotripsy. However, the underlying bubble dynamics and associated damage mechanisms are largely unknown. In this study, we use ultra-high-speed shadowgraph imaging, hydrophone measure ... Full text Open Access Cite

The use of histotripsy as intratumoral immunotherapy beyond tissue ablation-the rationale for exploring the immune effects of histotripsy.

Journal article Int J Hyperthermia · 2023 Mechanical high-intensity focused ultrasound (M-HIFU), which includes histotripsy, is a non-ionizing, non-thermal ablation technology that can be delivered by noninvasive methods. Because acoustic cavitation is the primary mechanism of tissue disruption, h ... Full text Link to item Cite

A Multi-Spark Electrohydraulic Shock Wave Generator with Adjustable Pressure Field Distribution and Beam Steering Capability.

Journal article Frontiers in urology · January 2023 Background and objectiveAll clinical shock wave lithotripters produce an axisymmetric acoustic field without accounting for the anatomic features of the kidney or respiratory motion of the patient. This work presents a steerable and adjustable foc ... Full text Cite

The Effects of Scanning Speed and Standoff Distance of the Fiber on Dusting Efficiency during Short Pulse Holmium: YAG Laser Lithotripsy.

Journal article J Clin Med · August 28, 2022 To investigate the effects of fiber lateral scanning speed across the stone surface (vfiber) and fiber standoff distance (SD) on dusting efficiency during short pulse holmium (Ho): YAG laser lithotripsy (LL), pre-soaked BegoStone samples were treated in wa ... Full text Link to item Cite

Cavitation Plays a Vital Role in Stone Dusting During Short Pulse Holmium:YAG Laser Lithotripsy.

Journal article J Endourol · May 2022 Featured Publication Objective: To investigate the mechanism of stone dusting in Holmium (Ho): YAG laser lithotripsy (LL). Materials and Methods: Cylindrical BegoStone samples (6 × 6 mm, H × D) were treated in water using a clinical Ho:YAG laser lithotripter in dusting mode (0 ... Full text Link to item Cite

Comparison of Different Pulse Modulation Modes for Holmium:Yttrium-Aluminum-Garnet Laser Lithotripsy Ablation in a Benchtop Model.

Journal article J Endourol · January 2022 Introduction: Manipulation of Holmium:Yttrium-Aluminum-Garnet laser parameters such as pulse energy (PE), frequency, and duration can impact laser lithotripsy ablation efficiency. In 2017, Lumenis introduced Moses™ Technology, which uses pulse modulation t ... Full text Link to item Cite

Combination of ultrasound-based mechanical disruption of tumor with immune checkpoint blockade modifies tumor microenvironment and augments systemic antitumor immunity.

Journal article J Immunother Cancer · January 2022 Featured Publication BACKGROUND: Despite multimodal adjuvant management with radiotherapy, chemotherapy and hormonal therapies, most surgically resected primary breast cancers relapse or metastasize. A potential solution to late and distant recurrence is to augment systemic an ... Full text Link to item Cite

Photoacoustic computed tomography of mechanical HIFU-induced vascular injury.

Journal article Biomedical optics express · September 2021 Mechanical high-intensity focused ultrasound (HIFU) has been used for cancer treatment and drug delivery. Existing monitoring methods for mechanical HIFU therapies such as MRI and ultrasound imaging often suffer from high cost, poor spatial-temporal resolu ... Full text Cite

Variations of stress field and stone fracture produced at different lateral locations in a shockwave lithotripter field.

Journal article The Journal of the Acoustical Society of America · August 2021 Featured Publication During clinical procedures, the lithotripter shock wave (LSW) that is incident on the stone and resultant stress field is often asymmetric due to the respiratory motion of the patient. The variations of the LSW-stone interaction and associated fracture pat ... Full text Cite

Time-Resolved Passive Cavitation Mapping Using the Transient Angular Spectrum Approach.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · July 2021 Passive cavitation mapping (PCM), which generates images using bubble acoustic emission signals, has been increasingly used for monitoring and guiding focused ultrasound surgery (FUS). PCM can be used as an adjunct to magnetic resonance imaging to provide ... Full text Cite

The Role of Cavitation in Energy Delivery and Stone Damage During Laser Lithotripsy.

Journal article J Endourol · June 2021 Featured Publication Purpose: Although cavitation during laser lithotripsy (LL) contributes to the Moses effect, the impact of cavitation on stone damage is less clear. Using different laser settings, we investigate the role of cavitation bubbles in energy delivery and stone d ... Full text Link to item Cite

Tri-modality cavitation mapping in shock wave lithotripsy.

Journal article The Journal of the Acoustical Society of America · February 2021 Featured Publication Shock wave lithotripsy (SWL) has been widely used for non-invasive treatment of kidney stones. Cavitation plays an important role in stone fragmentation, yet it may also contribute to renal injury during SWL. It is therefore crucial to determine the spatio ... Full text Cite

Internal-Illumination Photoacoustic Tomography Enhanced by a Graded-Scattering Fiber Diffuser.

Journal article IEEE transactions on medical imaging · January 2021 The penetration depth of photoacoustic imaging in biological tissues has been fundamentally limited by the strong optical attenuation when light is delivered externally through the tissue surface. To address this issue, we previously reported internal-illu ... Full text Cite

Optimal pulse length of insonification for Piezo1 activation and intracellular calcium response.

Journal article Scientific reports · January 2021 Featured Publication Ultrasound (US) neuromodulation, especially sonogenetics, has been demonstrated with potential applications in noninvasive and targeted treatment of various neurological disorders. Despite the growing interest, the mechanism for US neuromodulation remains ... Full text Cite

Mechanically induced integrin ligation mediates intracellular calcium signaling with single pulsating cavitation bubbles.

Journal article Theranostics · January 2021 Therapeutic ultrasound or shockwave has shown its great potential to stimulate neural and muscle tissue, where cavitation microbubble induced Ca2+ signaling is believed to play an important role. However, the pertinent mechanisms are unknown, es ... Full text Cite

Miniaturized Intracavitary Forward-Looking Ultrasound Transducer for Tissue Ablation.

Journal article IEEE Trans Biomed Eng · July 2020 OBJECTIVE: This paper aims to develop a miniaturized forward-looking ultrasound transducer for intracavitary tissue ablation, which can be used through an endoscopic device. The internal ultrasound (US) delivery is capable of directly interacting with the ... Full text Link to item Cite

Simultaneous Photoacoustic Imaging and Cavitation Mapping in Shockwave Lithotripsy.

Journal article IEEE transactions on medical imaging · February 2020 Kidney stone disease is a major health problem worldwide. Shockwave lithotripsy (SWL), which uses high-energy shockwave pulses to break up kidney stones, is extensively used in clinic. However, despite its noninvasiveness, SWL can produce cavitation in viv ... Full text Cite

Nanosecond shock wave-induced surface acoustic waves and dynamic fracture at fluid-solid boundaries.

Journal article Physical review research · November 2019 Featured Publication We investigate the generation and propagation characteristics of leaky Rayleigh waves (LRWs) caused by a spherical shock wave incident on a water-glass boundary both experimentally and numerically. The maximum tensile stress produced on the solid boundary ... Full text Cite

Activation of Piezo1 mechanosensitive ion channel in HEK293T cells by 30 MHz vertically deployed surface acoustic waves.

Journal article Biochemical and biophysical research communications · October 2019 Ultrasound (US) has emerged as a promising noninvasive modality for neuromodulation. Despite previous evidence that US may mediate cellular response by activating mechanosensitive ion channels embedded in the cell membrane, the underlying mechanism is not ... Full text Cite

Shock-Induced Damage and Dynamic Fracture in Cylindrical Bodies Submerged in Liquid.

Journal article International journal of solids and structures · September 2019 Understanding the response of solid materials to shock loading is important for mitigating shock-induced damages and failures, as well as advancing the beneficial use of shock waves for material modifications. In this paper, we consider a representative br ... Full text Cite

Thermal Memory Based Photoacoustic Imaging of Temperature.

Journal article Optica · February 2019 Temperature mapping is essential in many biomedical studies and interventions to precisely control the tissue's thermal conditions for optimal treatment efficiency and minimal side effects. Based on the Grüneisen parameter's temperature dependence, photoac ... Full text Cite

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

Journal article J Endourol · June 2018 PURPOSE: The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical ... Full text Link to item Cite

An experimentally-calibrated damage mechanics model for stone fracture in shock wave lithotripsy.

Journal article International journal of fracture · May 2018 A damage model suggested by the Tuler-Butcher concept of dynamic accumulation of microscopic defects is obtained from experimental data on microcrack formation in synthetic kidney stones. Experimental data on appearance of microcracks is extracted from mic ... Full text Cite

Dynamics and mechanisms of intracellular calcium waves elicited by tandem bubble-induced jetting flow.

Journal article Proceedings of the National Academy of Sciences of the United States of America · January 2018 Featured Publication One of the earliest events in cellular mechanotransduction is often an increase in intracellular calcium concentration associated with intracellular calcium waves (ICWs) in various physiologic or pathophysiologic processes. Although cavitation-induced calc ... Full text Cite

Comparison of Broad vs Narrow Focal Width Lithotripter Fields.

Journal article J Endourol · May 2017 OBJECTIVE: To investigate the impact of lithotripter focal width on stone fragmentation. MATERIALS AND METHODS: A modified reflector was used to reduce -6 dB beam size of the HM3 lithotripter, while increasing concomitantly peak pressure. Fragmentation in ... Full text Link to item Cite

A Microfluidic System with Surface Patterning for Investigating Cavitation Bubble(s)-Cell Interaction and the Resultant Bioeffects at the Single-cell Level.

Journal article Journal of visualized experiments : JoVE · January 2017 In this manuscript, we first describe the fabrication protocol of a microfluidic chip, with gold dots and fibronectin-coated regions on the same glass substrate, that precisely controls the generation of tandem bubbles and individual cells patterned nearby ... Full text Cite

Effects of Stone Size on the Comminution Process and Efficiency in Shock Wave Lithotripsy.

Journal article Ultrasound in medicine & biology · November 2016 The effects of stone size on the process and comminution efficiency of shock wave lithotripsy (SWL) were investigated in experiments, numerical simulations and scale analysis. Cylindrical BegoStone phantoms with approximately equal height and diameter of e ... Full text Cite

Comparison of the Nanopulse Lithotripter to the Holmium Laser: Stone Fragmentation Efficiency and Impact on Flexible Ureteroscope Deflection and Flow.

Journal article J Endourol · November 2016 INTRODUCTION: The Nanopulse Lithotripter (NPL; Lithotech Medical, Israel) is a novel intracorporeal device that uses a nanosecond duration electrical discharge through a reusable flexible coaxial probe to endoscopically fragment urinary stones. This device ... Full text Link to item Cite

Cell membrane deformation and bioeffects produced by tandem bubble-induced jetting flow.

Journal article Proceedings of the National Academy of Sciences of the United States of America · December 2015 Featured Publication Cavitation with bubble-bubble interaction is a fundamental feature in therapeutic ultrasound. However, the causal relationships between bubble dynamics, associated flow motion, cell deformation, and resultant bioeffects are not well elucidated. Here, we re ... Full text Cite

Bubble Proliferation or Dissolution of Cavitation Nuclei in the Beam Path of a Shock-Wave Lithotripter

Journal article Physical Review Applied · March 3, 2015 It is hypothesized that the decreased treatment efficiency in contemporary shock-wave lithotripters is related to tensile wave attenuation due to cavitation in the prefocal beam path. Utilizing high-speed imaging of the beam path and focal pressure wavefor ... Full text Cite

Shock wave lithotripsy: the new phoenix?

Journal article World J Urol · February 2015 INTRODUCTION: Following its introduction in 1980, shock wave lithotripsy (SWL) rapidly emerged as the first-line treatment for the majority of patients with urolithiasis. Millions of SWL therapies have since been performed worldwide, and nowadays, SWL stil ... Full text Link to item Cite

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter.

Journal article Proc Natl Acad Sci U S A · April 1, 2014 Featured Publication The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens ... Full text Open Access Link to item Cite

Probing the bioeffects of cavitation at the single-cell level.

Journal article J Acoust Soc Am · November 2013 Cavitation induced bioeffects has not been resolved satisfactorily due to the randomness in the inception and bubble dynamics produced by ultrasound. We have developed a microfluidic system to observe consistently the interaction of laser-generated tandem ... Full text Link to item Cite

Assessment of a modified acoustic lens for electromagnetic shock wave lithotripters in a swine model.

Journal article J Urol · September 2013 PURPOSE: The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessli ... Full text Link to item Cite

Experimentally validated multiphysics computational model of focusing and shock wave formation in an electromagnetic lithotripter.

Journal article The Journal of the Acoustical Society of America · August 2013 A multiphysics computational model of the focusing of an acoustic pulse and subsequent shock wave formation that occurs during extracorporeal shock wave lithotripsy is presented. In the electromagnetic lithotripter modeled in this work the focusing is achi ... Full text Cite

A heuristic model of stone comminution in shock wave lithotripsy.

Journal article J Acoust Soc Am · August 2013 A heuristic model is presented to describe the overall progression of stone comminution in shock wave lithotripsy (SWL), accounting for the effects of shock wave dose and the average peak pressure, P+(avg), incident on the stone during the treatment. The m ... Full text Link to item Cite

Turbulent water coupling in shock wave lithotripsy.

Journal article Phys Med Biol · February 7, 2013 Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93 ... Full text Link to item Cite

In-vitro assessment of a new portable ballistic lithotripter with percutaneous and ureteroscopic models.

Journal article J Endourol · November 2012 BACKGROUND AND PURPOSE: The EMS Swiss LithoBreaker is a new, portable, electrokinetic lithotripter. We compared its tip velocity and displacement characteristics with a handheld, pneumatic lithotripter LMA StoneBreaker.™ We also evaluated fragmentation eff ... Full text Link to item Cite

Stone comminution correlates with the average peak pressure incident on a stone during shock wave lithotripsy.

Journal article J Biomech · October 11, 2012 To investigate the roles of lithotripter shock wave (LSW) parameters and cavitation in stone comminution, a series of in vitro fragmentation experiments have been conducted in water and 1,3-butanediol (a cavitation-suppressive fluid) at a variety of acoust ... Full text Link to item Cite

Stereoscopic high-speed imaging using additive colors.

Journal article Rev Sci Instrum · April 2012 An experimental system for digital stereoscopic imaging produced by using a high-speed color camera is described. Two bright-field image projections of a three-dimensional object are captured utilizing additive-color backlighting (blue and red). The two im ... Full text Link to item Cite

M-HIFU inhibits tumor growth, suppresses STAT3 activity and enhances tumor specific immunity in a transplant tumor model of prostate cancer.

Journal article PLoS One · 2012 OBJECTIVE: In this study, we explored the use of mechanical high intensity focused ultrasound (M-HIFU) as a neo-adjuvant therapy prior to surgical resection of the primary tumor. We also investigated the role of signal transducer and activator of transcrip ... Full text Open Access Link to item Cite

Dynamics of tandem bubble interaction in a microfluidic channel.

Journal article J Acoust Soc Am · November 2011 The dynamics of tandem bubble interaction in a microfluidic channel (800  ×  21 μm, W × H) have been investigated using high-speed photography, with resultant fluid motion characterized by particle imaging velocimetry. A single or tandem bubble is produced ... Full text Link to item Cite

Optimization of treatment strategy used during shockwave lithotripsy to maximize stone fragmentation efficiency.

Journal article J Endourol · September 2011 BACKGROUND AND PURPOSE: Previous studies have demonstrated that treatment strategy plays a critical role in ensuring maximum stone fragmentation during shockwave lithotripsy (SWL). We aimed to develop an optimal treatment strategy in SWL to produce maximum ... Full text Open Access Link to item Cite

The digital flexible ureteroscope: In vitro assessment of optical characteristics

Journal article International Braz J Urol · May 1, 2011 Introduction: Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced ... Full text Cite

The digital flexible ureteroscope: in vitro assessment of optical characteristics.

Journal article J Endourol · March 2011 INTRODUCTION: Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced ... Full text Link to item Cite

Displacement of particles in microfluidics by laser-generated tandem bubbles.

Journal article Appl Phys Lett · November 1, 2010 The dynamic interaction between laser-generated tandem bubble and individual polystyrene particles of 2 and 10 μm in diameter is studied in a microfluidic channel (25 μm height) by high-speed imaging and particle image velocimetry. The asymmetric collapse ... Full text Open Access Link to item Cite

A simple method for fabricating artificial kidney stones of different physical properties.

Journal article Urol Res · August 2010 A simple method for preparing artificial kidney stones with varying physical properties is described. BegoStone was prepared with a powder-to-water ratio ranging from 15:3 to 15:6. The acoustic properties of the phantoms were characterized using an ultraso ... Full text Link to item Cite

Pulsating tandem microbubble for localized and directional single-cell membrane poration.

Journal article Physical review letters · August 2010 Featured Publication The interaction of laser-generated tandem microbubble (maximum diameter of about 50  μm) with single (rat mammary carcinoma) cells is investigated in a 25-μm liquid layer. Antiphase and coupled oscillation of the tandem microbubble leads to the formation o ... Full text Open Access Cite

Effect of lithotripter focal width on stone comminution in shock wave lithotripsy.

Journal article J Acoust Soc Am · April 2010 Using a reflector insert, the original HM-3 lithotripter field at 20 kV was altered significantly with the peak positive pressure (p(+)) in the focal plane increased from 49 to 87 MPa while the -6 dB focal width decreased concomitantly from 11 to 4 mm. Usi ... Full text Open Access Link to item Cite

A composite kidney stone phantom with mechanical properties controllable over the range of human kidney stones.

Journal article J Mech Behav Biomed Mater · January 2010 A novel composite kidney stone phantom has been developed. This stone phantom is producible with mechanical properties mimicking the range of tensile fracture strength and acoustic properties of human kidney stones and is an inorganic/organic composite mat ... Full text Link to item Cite

Boosting high-intensity focused ultrasound-induced anti-tumor immunity using a sparse-scan strategy that can more effectively promote dendritic cell maturation.

Journal article Journal of translational medicine · January 2010 BackgroundThe conventional treatment protocol in high-intensity focused ultrasound (HIFU) therapy utilizes a dense-scan strategy to produce closely packed thermal lesions aiming at eradicating as much tumor mass as possible. However, this strategy ... Full text Open Access Cite

Low-amplitude ultrasound enhances hydrodynamic-based gene delivery to rat kidney.

Journal article Biochemical and biophysical research communications · August 2009 The synergistic combination of hydrodynamic-based gene delivery and ultrasound was investigated to achieve improved gene transfer to the kidney. Plasmids encoding firefly luciferase and Erythropoietin (EPO) gene were delivered into the left kidney of rats ... Full text Cite

High definition laparoscopy: objective assessment of performance characteristics and comparison with standard laparoscopy.

Journal article J Endourol · March 2009 INTRODUCTION: High definition (HD) digital imaging represents a major advance in endoscope technology. The development of the charge-coupled device chip and its location at the distal end of the endoscope allows for image capture and digitization, as well ... Full text Link to item Cite

Activation of transgene expression in skeletal muscle by focused ultrasound.

Journal article Biochem Biophys Res Commun · February 6, 2009 To correlate thermal dose from focused ultrasound (FUS) with gene expression and tissue injury, a temperature plateau strategy was employed. Plasmids encoding luciferase gene under the control of hsp70B promoter were transfected into the right gastrocnemiu ... Full text Link to item Cite

The effect of high intensity focused ultrasound treatment on metastases in a murine melanoma model

Journal article AIP Conference Proceedings · 2009 This study aims to assess the risk of high intensity focused ultrasound (HIFU) therapy on the incidence of metastases and to investigate the association of metastasis incidence with HIFU-elicited anti-tumor immunity using a melanoma model. Tumor-bearing le ... Full text Cite

Ultrasound-mediated drug delivery.

Journal article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · January 2009 Full text Cite

Effect of shockwaves on the biomechanical and biochemical function of cells

Journal article Society for Experimental Mechanics 11th International Congress and Exhibition on Experimental and Applied Mechanics 2008 · December 1, 2008 The number of non-lethal cases of soldiers being exposed to blasts from improvised explosive devices (IED) has increased significantly over the last few years. Concurrently, the number of soft tissue injuries, including traumatic brain injuries (TBI) and h ... Cite

The effect of high intensity focused ultrasound treatment on metastases in a murine melanoma model.

Journal article Biochem Biophys Res Commun · October 31, 2008 This study aims to assess the risk of high intensity focused ultrasound (HIFU) therapy on the incidence of distant metastases and to investigate its association with HIFU-elicited anti-tumor immunity in a murine melanoma (B16-F10) model. Tumor-bearing legs ... Full text Link to item Cite

Focusing of shock waves induced by optical breakdown in water.

Journal article The Journal of the Acoustical Society of America · June 2008 The focusing of laser-generated shock waves by a truncated ellipsoidal reflector was experimentally and numerically investigated. Pressure waveform and distribution around the first (F(1)) and second foci (F(2)) of the ellipsoidal reflector were measured. ... Full text Cite

Investigation of HIFU-induced anti-tumor immunity in a murine tumor model.

Journal article J Transl Med · July 11, 2007 Featured Publication BACKGROUND: High intensity focused ultrasound (HIFU) is an emerging non-invasive treatment modality for localized treatment of cancers. While current clinical strategies employ HIFU exclusively for thermal ablation of the target sites, biological responses ... Full text Link to item Cite

The effect of frequency doubled double pulse Nd:YAG laser fiber proximity to the target stone on transient cavitation and acoustic emission.

Journal article J Urol · April 2007 PURPOSE: Scant information has been published describing the effect of laser fiber distance from the stone target on the mechanism of calculus fragmentation. Using high speed photography and acoustic emission measurements we characterized the impact of las ... Full text Link to item Cite

Assessment of shock wave lithotripters via cavitation potential.

Journal article Phys Fluids (1994) · 2007 A method to characterize shock wave lithotripters by examining the potential for cavitation associated with the lithotripter shock wave (LSW) has been developed. The method uses the maximum radius achieved by a bubble subjected to a LSW as a representation ... Full text Link to item Cite

Interaction of lithotripter shockwaves with single inertial cavitation bubbles.

Journal article J Fluid Mech · 2007 The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined wi ... Full text Link to item Cite

High intensity focused ultrasound-induced gene activation in solid tumors.

Journal article J Acoust Soc Am · July 2006 In this work, the activation of heat-sensitive trans-gene by high-intensity focused ultrasound (HIFU) in a tumor model was investigated. 4T1 cancer cells (2 x 10(6)) were inoculated subcutaneously in the hind limbs of Balb/C mice. The tumors were subsequen ... Full text Link to item Cite

Interaction between shock wave and single inertial bubbles near an elastic boundary

Journal article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics · 2006 The interaction of laser-generated single inertial bubbles (collapse time=121 μs) near a silicon rubber membrane with a shock wave (55 MPa in peak pressure and 1.7 μs in compressive pulse duration) is investigated. The interaction leads to directional, for ... Full text Cite

Citrate and vitamin E blunt the shock wave-induced free radical surge in an in vitro cell culture model.

Journal article Urol Res · December 2005 Free radical formation plays a major role in shock wave lithotripsy induced renal damage. Moreover, previous studies suggest that free radicals may also promote de novo calcium oxalate crystallization of previously damaged urothelium. Citrate is a known in ... Full text Link to item Cite

High intensity focused ultrasound-induced gene activation in sublethally injured tumor cells in vitro.

Journal article J Acoust Soc Am · November 2005 Cultured human cervical cancer (HeLa) and rat mammary carcinoma (R3230Ac) cells were transfected with vectors encoding green fluorescent protein (GFP) under the control of hsp70B promoter. Aliquots of 10-microl transfected cells (5 x 10(7) cells/ml) were p ... Full text Link to item Cite

Release of endogenous danger signals from HIFU-treated tumor cells and their stimulatory effects on APCs.

Journal article Biochem Biophys Res Commun · September 16, 2005 The effects of high-intensity focused ultrasound (HIFU) on the release of endogenous danger signals from tumor cells and subsequent activation of antigen-presenting cells (APCs) were evaluated in vitro. MC-38 mouse tumor cells were treated using a 1.1 MHz ... Full text Link to item Cite

Shock wave interaction with laser-generated single bubbles.

Journal article Physical review letters · July 2005 Featured Publication The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse o ... Full text Cite

In vitro comparison of stone retropulsion and fragmentation of the frequency doubled, double pulse nd:yag laser and the holmium:yag laser.

Journal article J Urol · May 2005 PURPOSE: The frequency doubled, double pulse Nd:YAG (FREDDY) laser (World of Medicine, Berlin, Germany) functions through the generation of a plasma bubble. Upon bubble collapse a mechanical shock wave is generated, causing stone fragmentation. This mechan ... Full text Link to item Cite

Ultrasound-induced cell detachment and gene transfection in adherent cells

Journal article Acoustic Research Letters Online · 2005 The effect of 1-MHz cw ultrasound (0.36 MPa in pressure amplitude) on cell detachment and gene transfection in adherent HeLa cells was investigated. Cell detachment, cell injury, and gene transfection (up to 50%) in surviving populations were found to incr ... Full text Cite

Innovations in shock wave lithotripsy technology: updates in experimental studies.

Journal article J Urol · November 2004 PURPOSE: We developed innovations in shock wave lithotripsy (SWL) technology. MATERIALS AND METHODS: Two technical upgrades were implemented in an original unmodified HM-3 lithotriptor (Dornier Medical Systems, Inc., Kennesaw, Georgia). First, a single uni ... Full text Link to item Cite

The effect of surface agitation on ultrasound-mediated gene transfer in vitro

Journal article JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA · October 2004 Full text Link to item Cite

In vitro comparison of fragmentation efficiency of flexible pneumatic lithotripsy using 2 flexible ureteroscopes.

Journal article J Urol · September 2004 PURPOSE: Pneumatic lithotripsy has been shown to be an effective and safe intracorporeal lithotripsy modality for renal and ureteral calculi, capable of fragmenting stones of all compositions. We determined the in vitro stone fragmentation abilities of the ... Full text Link to item Cite

The effect of treatment strategy on stone comminution efficiency in shock wave lithotripsy.

Journal article J Urol · July 2004 PURPOSE: The comminution of kidney stones in shock wave lithotripsy (SWL) is a dose dependent process caused primarily by the combination of 2 fundamental mechanisms, namely stress waves and cavitation. The effect of treatment strategy with emphasis on enh ... Full text Link to item Cite

The use of chemical treatments for improved comminution of artificial stones.

Journal article J Urol · May 2004 PURPOSE: The acoustic and mechanical properties of various stone compositions are significantly different and thus result in varying degrees of fragility. Consequently, results to shock wave lithotripsy (SWL) are influenced accordingly. We report the resul ... Full text Link to item Cite

Reduction of tissue injury in shock-wave lithotripsy by using an acoustic diode.

Journal article Ultrasound Med Biol · May 2004 An acoustic diode (AD) was constructed of two acoustic transparent membranes with good initial contact to allow the transmission of the positive pressure of lithotripter shock wave at an almost unaltered level, yet attenuate significantly its negative pres ... Full text Link to item Cite

Evaluation of a Bifocal Reflector on a Clinical Lithotripter: Editorial Comment

Journal article Journal of Endourology · February 1, 2004 Cite

Evaluation of synchronous twin pulse technique for shock wave lithotripsy: determination of optimal parameters for in vitro stone fragmentation.

Journal article J Urol · December 2003 PURPOSE: The Twinheads extracorporeal shock wave lithotriptor (THSWL) is composed of 2 identical shock wave generators and reflectors. One reflector is under the table and the other is over the table with a variable angle between the axes of the 2 reflecto ... Full text Link to item Cite

In vitro analysis of stone fragmentation ability of the FREDDY laser.

Journal article J Endourol · April 2003 BACKGROUND AND PURPOSE: The Frequency-Doubled Double-Pulse Nd:Yag) (FREDDY) laser (World of Medicine, Berlin Germany) is a short-pulsed, double-frequency solid-state laser with wavelengths of 532 and 1064 nm. This low-power, low-cost laser was developed fo ... Full text Link to item Cite

Shock wave lithotripsy causes ipsilateral renal injury remote from the focal point: the role of regional vasoconstriction.

Journal article J Urol · April 2003 PURPOSE: Shock wave lithotripsy induced renal damage can occur as a result of multiple mechanisms, including small vessel injury and free radical production. Previous studies have demonstrated that shock wave lithotripsy exerts a regional change in renal h ... Full text Link to item Cite

Clinical efficacy of a combination pneumatic and ultrasonic lithotrite.

Journal article J Urol · April 2003 PURPOSE: A new combination pneumatic/ultrasonic intracorporeal lithotriptor has been developed for percutaneous applications. It combines the stone clearing efficiency of an ultrasonic device with the fragmentation strength of a pneumatic probe into a sing ... Full text Link to item Cite

Optimization of lithotripter waveform to reduce tissue injury without compromising stone comminution

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 To reduce the potential of vascular injury without compromising stone comminution in shock wave lithotripsy, an in situ pulse superposition technique has been developed to suppress intraluminal bubble expansion by modifying an HM-3 reflector based on theor ... Cite

BegoStone - a new stone phantom for shock wave lithotripsy research (L)

Journal article Journal Of The Acoustical Society Of America · October 2002 Cite

In vitro comparison of standard ultrasound and pneumatic lithotrites with a new combination intracorporeal lithotripsy device.

Journal article Urology · July 2002 OBJECTIVES: A new combination intracorporeal lithotripter (Lithoclast Ultra) has been developed that incorporates the beneficial effects of pneumatic lithotripsy (rapid stone fragmentation) and ultrasound lithotripsy (rapid fragment removal). An in vitro s ... Full text Link to item Cite

The role of stress waves and cavitation in stone comminution in shock wave lithotripsy.

Journal article Ultrasound Med Biol · May 2002 Using an experimental system that mimics stone fragmentation in the renal pelvis, we have investigated the role of stress waves and cavitation in stone comminution in shock-wave lithotripsy (SWL). Spherical plaster-of-Paris stone phantoms (D = 10 mm) were ... Full text Link to item Cite

In vivo assessment of free radical activity during shock wave lithotripsy using a microdialysis system: the renoprotective action of allopurinol.

Journal article J Urol · January 2002 PURPOSE: Shock wave lithotripsy is believed to cause renal damage directly through cellular injury from high energy shock waves and indirectly through vascular injury and resultant ischemia, which gives rise to oxygen free radical compounds. The transient ... Link to item Cite

Suppression of large intraluminal bubble expansion in shock wave lithotripsy without compromising stone comminution: methodology and in vitro experiments.

Journal article J Acoust Soc Am · December 2001 To reduce the potential of vascular injury without compromising the stone comminution capability of a Dornier HM-3 lithotripter, we have devised a method to suppress intraluminal bubble expansion via in situ pulse superposition. A thin shell ellipsoidal re ... Full text Link to item Cite

Dynamic photoelastic study of the transient stress field in solids during shock wave lithotripsy.

Journal article J Acoust Soc Am · March 2001 Photoelastic and shadowgraph imaging techniques were used to visualize the propagation and evolution of stress waves, and the resultant transient stress fields in solids during shock wave lithotripsy. In parallel, theoretical analysis of the wavefront evol ... Full text Link to item Cite

Dynamics of bubble oscillation in constrained media and mechanisms of vessel rupture in SWL.

Journal article Ultrasound Med Biol · January 2001 Rupture of small blood vessels is a primary feature of the vascular injury associated with shock-wave lithotripsy (SWL) and cavitation has been implicated as a potential mechanism. To understand more precisely the underlying mechanical cause of the injury, ... Full text Link to item Cite

Quantification of the tip movement of lithotripsy flexible pneumatic probes.

Journal article J Urol · November 2000 PURPOSE: We developed an optical system to quantify in vitro tip movement of the Lithoclastdouble dagger flexible probe, and correlated various physical parameters of the vibrating probe tip with resultant stone fragmentation. MATERIALS AND METHODS: A nonc ... Link to item Cite

Microdialysis assessment of shock wave lithotripsy-induced renal injury.

Journal article Urology · September 1, 2000 OBJECTIVES: Shock wave lithotripsy (SWL) is the primary treatment modality for managing the majority of symptomatic renal calculi. However, the fundamental mechanisms for stone fragmentation and the resultant morphologic changes that occur are not fully un ... Full text Link to item Cite

Acoustic and mechanical properties of artificial stones in comparison to natural kidney stones.

Journal article J Urol · August 2000 PURPOSE: Standardized and reproducible artificial kidney stone models are important for performing comparative studies of different lithotripsy modalities. The acoustic and mechanical properties of renal calculi dictate the manner by which stones interact ... Link to item Cite

Physical properties of artificial stones made of natural materials (BON(N)-STONES) in comparison to natural and other artificial stones

Journal article Journal Fur Urologie Und Urogynakologie · March 23, 2000 From a clinical point of view the artificial stone phantoms known so far are a compromise for in vitro investigations. Concerning experiments on chemolysis they are not useable because they are not comparable to natural renal calculi. Therefore it was the ... Cite

Improvement of stone fragmentation during shock-wave lithotripsy using a combined EH/PEAA shock-wave generator-in vitro experiments.

Journal article Ultrasound Med Biol · March 2000 To control the collapse of cavitation bubbles induced during shock-wave lithotripsy (SWL), a piezoelectric annular array (PEAA) shock-wave generator was fabricated and combined with an experimental electrohydraulic (EH) shock-wave lithotripter with a trunc ... Full text Link to item Cite

Shock wave-inertial microbubble interaction: a theoretical study based on the Gilmore formulation for bubble dynamics.

Journal article The Journal of the Acoustical Society of America · November 1999 The Gilmore formulation for bubble dynamics coupled with zeroth-order gas diffusion were used to investigate theoretically the cavitation activity produced by a modified XL-1 lithotripter [J. Acoust. Soc. Am. 105, 1997-2009 (1999)]. The model calculation c ... Full text Cite

Recent developments in SWL physics research.

Journal article J Endourol · November 1999 Two projects in our laboratory highlight some recent developments in shockwave lithotripsy (SWL) physics research. In the first project, we developed a prototype of a piezoelectric annular array (PEAA) shockwave generator that can be retrofitted on a Dorni ... Full text Link to item Cite

How to improve lithotripsy and chemolitholysis of brushite-stones: an in vitro study.

Journal article Urol Res · August 1999 Because of their resistance to fragmentation, treatment of brushite stones is a big problem. This study was performed to look for an improvement in therapeutic strategies by using artificial stones made of brushite (Bon(n)-stones), which are comparable to ... Full text Link to item Cite

Shock wave-inertial microbubble interaction: methodology, physical characterization, and bioeffect study.

Journal article J Acoust Soc Am · March 1999 A method of generating in situ shock wave-inertial microbubble interaction by a modified electrohydraulic shock wave lithotripter is proposed and tested in vitro. An annular brass ellipsoidal reflector (thickness = 28 mm) that can be mounted on the apertur ... Full text Link to item Cite

Influence of chemolysis on physical properties and comminution of artificial stones (BON(N)-STONES)

Journal article Aktuelle Urologie · 1999 Purpose: Acoustic and mechanical properties show significant differences among various stone compositions and are important parameters for the determination of stone fragility under shock wave impact. Suggesting that stone fragility and thus shock wave lit ... Cite

Influence of chemolysis on physical properties and comminution of artificial stones (BON(N)-STONES)

Journal article Aktuelle Urologie · January 1, 1999 Purpose: Acoustic and mechanical properties show significant differences among various stone compositions and are important parameters for the determination of stone fragility under shock wave impact. Suggesting that stone fragility and thus shock wave lit ... Full text Cite

Impact of holmium laser settings and fiber diameter on stone fragmentation and endoscope deflection.

Journal article J Endourol · December 1998 We compared the impact of various energy settings, frequency, and fiber diameters on the stone fragmentation capabilities of the holmium laser. Stone phantoms, made from plaster of Paris and uniform in weight, were treated with one of two laser fiber sizes ... Full text Link to item Cite

Transient cavitation and acoustic emission produced by different laser lithotripters.

Journal article J Endourol · August 1998 Transient cavitation and shockwave generation produced by pulsed-dye and holmium:YAG laser lithotripters were studied using high-speed photography and acoustic emission measurements. In addition, stone phantoms were used to compare the fragmentation effici ... Full text Link to item Cite

Laboratory and clinical assessment of pneumatically driven intracorporeal lithotripsy.

Journal article J Endourol · April 1998 A pneumatically driven intracorporeal lithotripter (the Swiss Lithoclast) has recently been approved for use in the United States. We compared its performance in vitro with ultrasonic, electrohydraulic and laser lithotripsy devices using a standard plaster ... Full text Link to item Cite

Controlled, forced collapse of cavitation bubbles for improved stone fragmentation during shock wave lithotripsy.

Journal article J Urol · December 1997 The feasibility of using controlled, forced collapse of cavitation bubbles for improved stone fragmentation during shock wave lithotripsy was demonstrated using microsecond tandem shockwave pulses. High-speed photography revealed that a secondary shock wav ... Full text Link to item Cite

Inertial cavitation and associated acoustic emission produced during electrohydraulic shock wave lithotripsy.

Journal article J Acoust Soc Am · May 1997 The inertial cavitation and associated acoustic emission generated during electrohydraulic shock wave lithotripsy were studied using high-speed photography and acoustic pressure measurements. The dynamics of cavitation bubble clusters, induced in vitro by ... Full text Link to item Cite

Transient oscillation of cavitation bubbles near stone surface during electrohydraulic lithotripsy.

Journal article J Endourol · February 1997 Using high-speed photography and acoustic emission measurements, we studied the dynamics of a transient cavitation bubble near a stone surface and the concomitant shockwaves generated during electrohydraulic lithotripsy (EHL). At each spark discharge, a va ... Full text Link to item Cite

Mechanisms of differing stone fragility in extracorporeal shockwave lithotripsy.

Journal article J Endourol · August 1994 Clinical experience with extracorporeal shockwave lithotripsy (SWL) has demonstrated significant variations in stone fragility. To understand the physical mechanisms of the differences, we quantitatively determined shockwave-stone interaction under clinica ... Full text Link to item Cite

Differing modes of shock-wave generation.

Journal article Semin Urol · February 1994 Link to item Cite

Acoustic and mechanical properties of renal calculi: implications in shock wave lithotripsy.

Journal article J Endourol · December 1993 The acoustic and mechanical properties of renal calculi dictate how a stone interacts with the mechanical forces produced by shock wave lithotripsy; thus, these properties are directly related to the success of the treatment. Using an ultrasound pulse tran ... Full text Link to item Cite

Propagation of shock waves in elastic solids caused by cavitation microjet impact. II: Application in extracorporeal shock wave lithotripsy.

Journal article J Acoust Soc Am · July 1993 To better understand the mechanism of stone fragmentation during extracorporeal shock wave lithotripsy (ESWL), the model developed in Part I [P. Zhong and C.J. Chuong, J. Acoust. Soc. Am. 94, 19-28 (1993)] is applied to study cavitation microjet impingemen ... Full text Link to item Cite

Propagation of shock waves in elastic solids caused by cavitation microjet impact. I: Theoretical formulation.

Journal article J Acoust Soc Am · July 1993 To understand the physical process of the impingement of cavitation microjet and the resultant shock wave propagation in an elastic solid, a theoretical model using geometrical acoustics was developed. Shock waves induced in both the jet head (water) and t ... Full text Link to item Cite

Characterization of fracture toughness of renal calculi using a microindentation technique

Journal article Journal of Materials Science Letters · 1993 We report our results on the characterization of fracture toughness of renal calculi of various compositions. A microindentation technique was used to determine stone hardness. The results showed distinct differences in fracture toughness of renal calculi ... Cite

Microhardness measurements of renal calculi: regional differences and effects of microstructure.

Journal article J Biomed Mater Res · September 1992 Microhardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (10%)/calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calc ... Full text Link to item Cite

A comparison of stone damage caused by different modes of shock wave generation.

Journal article J Urol · July 1992 A standard stone phantom was used to compare stone damage after extracorporeal shock wave administration from electrohydraulic, electromagnetic and piezoelectric lithotripters. For each machine, a low and high shock wave intensity setting was chosen: 18 & ... Full text Link to item Cite