نتایج جستجو برای: ultrasonic tissue characterization
تعداد نتایج: 1289261 فیلتر نتایج به سال:
Introduction: one of the minimally invasive methods of treatmenting liver malignancies is Radiofrequency Ablation (RFA) which can be applied to primary or secondary tumors. Nevertheless, the disease recurrence is probable after RFA application partially due to the inadequate capability of temperature monitoring of the target tissue and visualizing the thermal damage. The goal of this work was t...
High resolution ultrasonic imaging requires high frequency wide band ultrasonic transducers, which produce short pulses and highly focused beam. However, currently the frequency of ultrasonic transducers is limited to below 100 MHz, mainly because of the challenge in precise control of fabrication parameters. This paper reports the design, fabrication, and characterization of sensitive broadban...
It is well known that, in focused ultrasonic systems, the radiated beams through tissues converge around a focal point. This phenomenon produces a temperature increment over 56°C in few seconds, at the focus by the mechanical waves energy transformation into heat, due to acoustic absorption in the tissue. This can originate thermal coagulation, instantaneous cell damage or instantaneous ablatio...
The Cavitron ultrasonic surgical aspirator causes localised ultrasonic tissue fragmentation and has recently been used to remove intracranial tumours. We have examined tissue fragments from 17 operations in which the apparatus was used: in all cases a definitive diagnosis could be made from the material aspirated. This finding has not been previously described.
This work aims to evaluate the efficiency of ultrasonic degassing when applied to the AlSi9Cu3 alloy when compared with other degassing techniques. The mechanism of aluminium degassing is discussed. A suitable ultrasonic degassing apparatus including a novel MMM (Multi-frequency Multimode Modulated) technology, able to supply up to 1.2 kW power under a frequency up to 25 kHz, was developed spec...
This letter discusses the role electrical anisotropy plays in the structural integrity assessment of polycrystalline titanium alloys from the standpoint of fatigue crack detection and the related issue of microstructural noise. In eddy current inspection of noncubic crystallographic classes of polycrystalline metals the electric anisotropy of individual grains produces an inherent microstructur...
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