ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A novel, portable radiometer has been developed for routine calibration of the time-averaged ultrasonic power radiated from ultrasonic therapy devices. The radiometer combines a precision electrobalance with a reflecting target. The balance was calibrated at 5 watts at 1 MHz and at 1 watt at 1.6 and 3.7 MHz. The useful ranges of frequency and power were estimated to be from 0.8 to 4 MHz and 0.5 to 5 watts, respectively.

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The goal of this study was to investigate,in vivo, human liver tissue differentiation by ultrasound. This investigation was carried out through implementation of pattern recognition techniques. Values of the power spectra of the attenuation coefficient for normal liver tissues were estimated, and 25 of these values were selected to form the reference feature vector. A decision rule based on the normalized Euclidean distance between the feature vector of the liver under consideration and the reference vector was applied to decide whether tissue was normal or abnormal. This study was a continuation of a previous one (Chu, et al., 1985). In the previous study, curve fitting techniques were used to differentiate between the spectra of normal and abnormal liver cases. It was anticipated that results based on this study would be found more accurate and more informative than the results of the previous study.

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Initial attempts to clear obstructed arteries using laser angioplasty have shown the method to be feasible, but both safety and efficacy were limited due to laser or mechanical perforation of the arterial wall and insufficient width of the tunnels through the occlusions. Recent progress includes better detection of atheromatous plaques with fluorescence spectrometry or improved angioscopy and more precise delivery of laser energy via optical fibers. There is also a tendency to replace the formerly used bar fiber tips with tips protected by a sapphire probe, or to use quartz-shielded fiber bundles, in order to protect the arterial wall from mechanical perforation and the fiber tip from backburning. The most commonly used laser sources are argon, Nd-YAG and CO2.However, excimer and dye-pulsed lasers are attractive because the former creates smooth-edged lesions without thermal injury to the adjacent tissue, and the latter permits selective ablation of atheromatous tissue. Lasers are also being used in human peripheral artery disease to heat a metal probe at the fiber tip to melt the arterial obstructions. Although the above devices were able to penetrate arterial occlusions, complementary balloon angioplasty was required to obtain effective recanalization, regardless of the laser device used.

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A digital biotelemetry system has been designed and built which provides conventional asynchronous data communication at 9600 baud. Various sample rates are possible for the analog input voltage channels, including one channel at 460 Hz, four channels at 160 Hz, and two channels at 10 Hz. The data are acquired, stored and displayed using a personal computer. The transmitter is controlled with a MC68HC11 CMOS sigle-chip microprocessor, allowing low-power operation.

ISSN:0363-8855    

出版商:OVID    

年代:1988

数据来源: OVID