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). Cavitation was affected by PRF and by the power level (PL) of the lithotripter. At slow PRF, such as shots fired many seconds apart, cavitation was relatively sparse and bubble clouds flowed in the direction of SW propagation. When PRF was increased, the bubble clouds generated by one SW were amplified by subsequent SWs. Cloud amplification was accompanied by an apparent change in the pattern of bubble migration. Whereas bubbles continued to enter the field of view from the prefocal side, the main bubble cloud remained near the focal point. This was due to a streaming of bubbles opposite to the direction of SW propagation. Increasing the PL grew the cavitation field and enhanced the flow of bubbles opposite to the direction of SW propagation. Stepping up the PL acted to push the broad cloud progressively prefocally (toward the SW source), shifting the position of the plane at which the opposing directional bubble flows collided. (NIH DK43881

Progress in Lithotripsy Research

Shock wave lithotripsy (SWL) for the non-invasive treatment of kidney stones was introduced in the United States in 1984. SWL virtually eliminated the need for open surgery to remove kidney stones, and it did not take long for physicians and patients to endorse this revolutionary technology. Early reports told of the efficient removal of even the most troublesome stones without apparent complications, and SWL quickly became the "treatment modality of choice." It was not long, however, before concerned physicians began to report the occurrence of adverse effects in SWL, particularly involving vascular trauma and including cases of severe hemorrhage in the kidney and acute renal failure — significant side effects of serious consequence. Researchers quickly recognized the challenge and opportunity to determine the mechanisms of shock wave action in lithotripsy, and in 1988, the Acoustical Society of America held the first in a series of popular sessions devoted to the topic of shock waves in medicine. The goal of the inaugural session was to improve the fundamental understanding of lithotripsy — to bring better devices and treatments to patients. The goal of this paper is to report on progress in this effort

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. The microbubbles can be excited by an extracorporeal source of quasi-collimated ultrasound. Alternatively, the microbubbles can be excited by an intraluminal source, such as a fiber-optic laser. With either excitation technique, calcium-adhering microbubbles can significantly increase rates of erosion, pitting, and fragmentation of stones. We report here on new experiments using high-speed photography to characterize microbubble expansion and collapse. The bubble geometry observed in the experiments was used as one of the initial shapes for the numerical modeling. The modeling showed that the bubble dynamics strongly depends on bubble shape and stand-off distance. For the experimentally observed shape of microbubbles, the numerical modeling showed that the collapse of the microbubbles was associated with pressure increases of some two-to-three orders of magnitude compared to the excitation source pressures. This in-vitro study provides key insights into the use of microbubbles with calcium-adhering moieties in treatment of urinary stones

Tests of a tuner for a 325 MHz SRF spoke resonator

Fermilab is developing 325 MHz SRF spoke cavities for the proposed Project X. A compact fast/slow tuner has been developed for final tuning of the resonance frequency of the cavity after cooling down to operating temperature and to compensate microphonics and Lorentz force detuning [2]. The modified tuner design and results of 4.5K tests of the first prototype are presented. The performance of lever tuners for the SSR1 spoke resonator prototype has been measured during recent CW and pulsed tests in the Fermilab SCTF. The tuner met or exceeded all design goals and has been used to successfully: (1) Bring the cold cavity to the operating frequency; (2) Compensate for dynamic Lorentz force detuning; and (3) Compensate for frequency detuning of the cavity due to changes in the He bath pressure

Dynamic nonlinear focal shift in amplitude modulated moderately focused acoustic beams

[EN] The phenomenon of the displacement of the position of the pressure, intensity and acoustic radiation force maxima along the axis of focused acoustic beams under increasing driving amplitudes (nonlinear focal shift) is studied for the case of a moderately focused beam excited with continuous and 25 kHz amplitude modulated signals, both in water and tissue. We prove that in amplitude modulated beams the linear and nonlinear propagation effects coexist in a semi-period of modulation, giving place to a complex dynamic behavior, where the singular points of the beam (peak pressure, rarefaction, intensity and acoustic radiation force) locate at different points on axis as a function of time. These entire phenomena are explained in terms of harmonic generation and absorption during the propagation in a lossy nonlinear medium both for a continuous and an amplitude modulated beam. One of the possible applications of the acoustic radiation force displacement is the generation of shear waves at different locations by using a focused mono-element transducer excited by an amplitude Modulated signal. (C) 2016 Elsevier B.V. All rights reserved.FC acknowledge financial support from the AICO/2016-108 program of the Generalitat Valenciana. NJ acknowledge financial support from the FPI Grant PAID-2011 from the Universitat Politecnica de Valencia. NGS acknowledge financial support from DPI2013-42236-R Project of the Spanish Ministry of Economy and Competitiveness, S2013/MIT-3024 of the Community of Madrid and from FPU Grant 12/02187 from the Spanish Ministry of Education, Culture and Sport.Jimenez, N.; Camarena Femenia, F.; González-Salido, N. (2017). Dynamic nonlinear focal shift in amplitude modulated moderately focused acoustic beams. Ultrasonics. 75:106-114. https://doi.org/10.1016/j.ultras.2016.11.021S1061147

Клинико-морфологические особенности острой пневмонии у детей раннего возраста с первичными иммунодефицитами

This article displays results of clinical and morphological comparison of acute pneumonia (AP) in 32 infants with signs of primary immune deficiency (PID). Etiology AP and a form of PID were recognized by means of a complex of immunological testing during the patients’ lifetime and post-mortem immunohistochemical, histobacterioscopic, and bacteriological examinations. Principal distinguishing features of AC under PID background were: 1) mixed etiology of the disease, in which viral-and-bacterial-and-mycotic associations acquire the great importance; 2) a significant extension of lung tissue injury with predominance of an alternative component of inflammation; 3) a tendency of infectious and inflammatory lung processes to generalization.В статье представлены результаты клинико-патологоанатомических сопоставлений при острых пневмониях (ОП) у 32 детей с проявлениями первичного иммунодефицита (ПИД). Этиология ОП и форма ПИД установлены с помощью комплекса прижизненных иммунологических и посмертных иммуногистохимических, гистобактериоскопических и бактериологических методов исследования. Основными отличительными особенностями ОП при ПИД были: 1) смешанная этиология заболевания, в которой приобретают ведущее значение вирусно-бактериально-грибковые ассоциации; 2) значительный объем поражения легочной ткани с преобладанием альтернативного компонента воспаления; 3) склонность инфекционно-воспалительного процесса в легких к генерализации