No abstract available.
Acoustics*

No abstract available.
Acoustics*

Developing an acoustic radiation force excitation module including 64 channels based in FPGA for ultrasound elastography. The circuit of the module was derived in bipolar, and the parameters such as excitation frequency, pulse repetition frequency, pulse number, element number and focus depth were adjustable. The acoustic field for special parameter was experimented with OptiSon laser acoustic field system with a result which reflects the width of focal spot is about 3 mm. The acoustic power was experimented with RFB2000 radiation force balance with a result which reflects acoustic power is increasing linearly with the number of pulses and the number of elements, and is increasing squarely with the peak-to-peak value of excitation voltage. The module is promising in factual application which can be triggered externally in synchronously, and can be combined with B-mode ultrasound system for ultrasound elastography.
Acoustics ; Elasticity Imaging Techniques ; Ultrasonics

The acoustic properties of ultrasound and the interaction of biomaterial and cavitation are analyzed. The relation between ultrasonic parameters and sonication is indicated. Our research revealed that different sonication aims must well match with different acoustic properties for optimizing the sonication technology. Based on the theory of wave superposition, a method for enhancement of ultrasonic intensity in wide dimension is introduced. A large scale powerful polyhedral acoustic field is built according to the research above. The rationality and effectiveness of the method are demonstrated through examination.
Acoustics ; Biocompatible Materials ; Humans ; Sonication ; Ultrasonics

Over the past decades, ultrasound imaging technology has made tremendous progress in obtaining important diagnostic information from patients in a rapid, noninvasive manner. Although the technology has benefited from sophisticated signal processing technology and imaging system integration, much of this progress has been derived from the development of ultrasonic transducers that are in direct contact with patients. An overview of medical ultrasonic imaging transducers is presented in this review that describes their structure, types, and application fields. The structural components of a typical transducer are presented in detail including an active layer, acoustic matching layers, a backing block, an acoustic lens, and kerfs. The types of transducers are classified according to the dimensions of ultrasound images: one-dimensional array, mechanical wobbling, and two-dimensional array transducers. Advantages of each transducer over the other and the technical issues for further performance enhancement are described. Application of the transducers to various clinical imaging fields is also reviewed.
Acoustics ; Diagnostic Imaging* ; Humans ; Transducers* ; Ultrasonics* ; Ultrasonography

PURPOSE: To define the histologic correlation of the ultrsonic gastric wall layers of resected human gastric specimens. MATERIALS AND METHODS: UItrasound images of the gastric wall by using 5 or 7.5 MHz linear transducer were compared with the corresponding histologic sections of 30 surgically resected human gastric specimens. RESULTS: Five layers seen from within on ultrasound images of the normal gastric wall corresponded to (1) the acoustic interface between fluid bathing the surgical specimen and the mucosal surface and a portion of the superficial mucosa, (2) the deep mucosa including the muscularis mucosae and most of the superficial mucosa, (3) the submucosa plus the acoustic interface between the submucosa and the muscularis propria, (4) the muscularis propria minus the acoustic interface between the submucosa and the muscularis propria, and (5) the serosa and the subserosal tissue plus the acoustic interface between the serosa and the fluid bathing the surgical specimen. Ultrasonic findings in gastric carcinomas corresponded to their histopathologic findings. CONCLUSION: Histologic correlation of the ultrasonic gastric wall layers will provide us with a very useful and objective basis of gastric ultrasonography.
Acoustics ; Baths ; Humans ; Mucous Membrane ; Serous Membrane ; Transducers ; Ultrasonics* ; Ultrasonography

Ultrasonography is a useful diagnostic modality in evaluating the non-visualized kidney on IVP because visualization by this technique depends only on the morphologic and acoustic characteristics of the kidney and is independent of renal function. This non-invasive technique can accurately guide percutaneous puncture of the collecting system, permitting antegrade localization of the obstructing lesion, and percutaneous nephrostomy under the ultrasonic guidance can be performed as a means for rapid, usually temporary, urinary diversion in patients with obstructive uropathy. Many causes of IVP non-visualization have a typical sonographic appearance. 35 patients with non-visualized kidney were examined ultrasonically and 13 AGP were carried out.
Acoustics ; Humans ; Kidney ; Nephrostomy, Percutaneous ; Punctures ; Ultrasonics* ; Ultrasonography ; Urinary Diversion

PURPOSE: The aim of this experimental study was to evaluate whether the acoustic radiation force (ARF) is a potential source of twinkling artifacts in color Doppler images. METHODS: Color Doppler images were obtained using a clinical ultrasonic scanner (Voluson e, GE Healthcare) for a high contrast (+15 dB) circular scattering phantom at pulse repetition frequencies (PRFs) ranging from 0.1 to 13 kHz. Ultrasound transmissions resulting in ARF were measured using a hydrophone at the various PRFs considered. The influence of ARF on the appearance of twinkling colors was examined via the common parameter PRF. This methodology is based on the fact that alternating positive and negative Doppler shifts induced by the ARF are centered at a PRF twice the maximum Doppler frequency on the color scale bar, whereas the twinkling color aliasing is expected to remain similar regardless of PRF. RESULTS: Color twinkling artifacts were observed to be most conspicuous at the lowest PRF of 0.1 kHz. The extent of twinkling rapidly decreased as the PRF increased, eventually disappearing when the PRF > or =0.6 kHz. The measured ultrasound transmissions, however, were found to be insensitive to the PRF, and therefore it can be inferred that the PRF was insensitive to the ARF. CONCLUSION: Based on our experimental observations, the ARF may not be a source of color Doppler twinkling artifacts.
Acoustics* ; Artifacts* ; Doppler Effect ; Ultrasonics ; Ultrasonography ; Ultrasonography, Doppler, Color

PURPOSE: The number of the repatriated Korean students who had overseas study at early ages is increasing. They received foreign education, they can speak international languages, but they have many difficulties in articulation and intonation of the Korean language. This study aims to measure closure and aspiration duration, length of consonants, length of subsequent vowels, and ratio of consonants against subsequent vowels in vowel-consonant-vowel (VCV) syllables. METHODS: This study compares the acoustic and phonetic characteristics of repatriated and native students, the ratio of articulation error of Korean plosives, the closure and aspiration duration, and the ratio of the aspiration duration against the closure duration. RESULTS: The ratio of articulation error of Korean plosives between repatriated and native students is 19% and 2%, respectively. The closure duration was significantly longer in repatriated students than in native students. The aspiration duration was significantly longer in repatriated students than in native students. No difference was found in the ratio of aspiration duration against closure duration between the native and repatriated students. CONCLUSION: This study can be a good reference for estimating the phonetic difficulties of Korean elementary students who had overseas study at early ages.
Acoustics ; Humans

No abstract available.
Acoustics* ; Voice*