Numerical Analysis of Kidney Stone Fragmentation by Short Pulse Impingement

Mihradi, Sandro; Homma, Hiroomi; Kanto, Yasuhiro

doi:10.1299/jsmea.47.581

Cited by 9 publications

(11 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular for the studies here we found that the passage of the shock wave in the fluid surrounding the stone generated shear waves or surface waves at the "equatorial" surface of the stone which propagated into the stone and interfered constructively with other waves to generate the peak stresses. This conflicts with the conclusions of Mihradi et al 11 that the classical spall or Hopkinson effect is responsible for the peak tensile stresses in the stone. The probable explanation for this is that the waveform they used did not have a short shock front and as we show in Fig.…”

Section: Discussioncontrasting

confidence: 96%

“…Cleveland and Tello 10 described a FDTD model for calculating pressure waves in kidney stones subject to lithotripsy shock waves but the model treated the stone as a fluid and neglected the presence of shear waves. Mihradi et al 11 employed a finite-element model ͑FEM͒ to predict the stress loadings on kidney stones in lithotripsy. The incident waveform was modeled as a half-sinusoid of purely positive pressure and simulations were carried out for pulses of different durations ͑0.5 to 5 s͒ in a two-dimensional Cartesian coordinate system.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy

Cleveland

Sapozhnikov

2005

The Journal of the Acoustical Society of America

106

105

View full text Add to dashboard Cite

A time-domain finite-difference solution to the equations of linear elasticity was used to model the propagation of lithotripsy waves in kidney stones. The model was used to determine the loading on the stone (principal stresses and strains and maximum shear stresses and strains) due to the impact of lithotripsy shock waves. The simulations show that the peak loading induced in kidney stones is generated by constructive interference from shear waves launched from the outer edge of the stone with other waves in the stone. Notably the shear wave induced loads were significantly larger than the loads generated by the classic Hopkinson or spall effect. For simulations where the diameter of the focal spot of the lithotripter was smaller than that of the stone the loading decreased by more than 50%. The constructive interference was also sensitive to shock rise time and it was found that the peak tensile stress reduced by 30% as rise time increased from 25 to 150 ns. These results demonstrate that shear waves likely play a critical role in stone comminution and that lithotripters with large focal widths and short rise times should be effective at generating high stresses inside kidney stones.

show abstract

Section: Discussioncontrasting

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy

Cleveland

Sapozhnikov

2005

The Journal of the Acoustical Society of America

106

105

View full text Add to dashboard Cite

show abstract

“…Among them, spalling (Xi and Zhong 2001; Mihradi et al 2004), cavitation (Zohdi and Szeri 2005) and shear wave stress (Cleveland and Sapozhnikov 2005) have been shown to depend critically on the size or geometry of the stone. Furthermore, acoustic pulse energy E eff (Koch and Grunewald 1989; Granz and Köhler 1992; Delius et al 1994; Eisenmenger 2001) and peak average pressure ( P +(avg) ) incident on the stone (Smith and Zhong 2012) are two of the lithotripter field parameters that have been correlated with SC.…”

Section: Introductionmentioning

confidence: 99%

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

Zhang

Nault

Mitran

et al. 2016

Ultrasound in Medicine & Biology

View full text Add to dashboard Cite

The effects of stone size on the process and comminution efficiency in shock wave lithotripsy (SWL) are investigated by experiments, numerical simulations, and scale analysis. Cylindrical BegoStone phantoms with approximately equal height and diameter of either 4-, or 7- or 10-mm, in a total aggregated mass of about 1.5 g, were treated in an electromagnetic shock wave lithotripter field. The resultant stone comminution (SC) was found to correlate closely with the average peak pressure, P+(avg), incident on the stones. The P+(avg) threshold to initiate stone fragmentation in water increased from 7.9 to 8.8 to 12.7 MPa, respectively, when the stone size decreased from 10 to 7 to 4 mm. Similar changes in the P+(avg) threshold were observed for the 7- and 10-mm stones treated in 1,3-butanediol where cavitation is suppressed, suggesting that the observed size dependency is due to changes in stress distribution within different size stones. Moreover, the slope of the correlation curve between SC and ln(Pfalse‒+(avg)) in water increased with decreasing stone size, while the opposite trend was observed in 1,3-butanediol. The progression of stone comminution in SWL showed a size-dependency with the 7- and 10-mm stones fragmented into progressively smaller pieces while a significant portion (> 30%) of the 4-mm stones were stalemated within the size range of 2.8 ~ 4 mm even after 1,000 shocks. Analytical scaling considerations suggest size-dependent fragmentation behaviour, a hypothesis further supported by numerical model calculations that exhibit changing patterns of constructive and destructive wave interference, and thus variations in the maximum tensile stress or stress integral produced in cylindrical and spherical stone of different sizes.

show abstract

“…Concomitant blast waves may not entirely be detrimental to us. A biomedical application such as the lithotripter shock wave technique, that uses the concept of concomitant shock waves to fragment kidney stones, has already been in use for the betterment of humankind . The severity of head injuries caused by the concomitant blast wave is generally related to the peak overpressure and pulse duration of the incident blast pulse and the incoming direction of blast relative to the sagittal axis of the head.…”

Section: Introductionmentioning

confidence: 99%

Impact of complex blast waves on the human head: a computational study

Tan

Chew

Tse

et al. 2014

Numer Methods Biomed Eng

View full text Add to dashboard Cite

Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head-helmet model for blast impact analyses in Abaqus(TM) (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330 kPa is registered at the parietal lobe which exceeds the 235 kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at the temporal and parietal lobes when compared with results from the single frontal blast case. By analyzing the pressure wave flow surrounding the head and correlating them with the consequential evolution of ICP and skull stress, the paper provides insights into the interaction mechanics between the concomitant blast waves and the biological head model.

show abstract

Numerical Analysis of Kidney Stone Fragmentation by Short Pulse Impingement

Cited by 9 publications

References 10 publications

Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy

Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy

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

Impact of complex blast waves on the human head: a computational study

Contact Info

Product

Resources

About