نتایج جستجو برای: attenuation measurement
تعداد نتایج: 486908 فیلتر نتایج به سال:
CONTEXT There is extensive overlap among the imaging characteristics of pseudocyst, mucinous cystic neoplasm (MCN) and side branch intraductal papillary mucinous neoplasm (IPMN) on CT images. OBJECTIVE The purpose of this study was to evaluate the usefulness of attenuation measurement in differentiating pseudocysts from MCN and IPMN of pancreas on CT images. PATIENTS Seventy-five pathologic...
The National Aeronautics and Space Administration Advanced Communications Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the United States and Canada for use in the design of low-margin Ka-band satellite communication systems. Experimenters at seven different locations have collected propagation data for more than...
For the measurement of induced activity in the activation foils, various methods and instruments are used. When the activity is measured by using a beta counter it is very important to know the beta attenuation in the activation foils. The beta attenuation in the foil depends on the beta spectrum of the activation product, the material and the thickness of the material. The beta attenuation has...
Attenuation measurements can be derived from the decay of backscattered signal with depth in an inhomogeneous material. In cases such as liver tissue, where many small inhomogeneities are likely to be included in sample volumes defined by pulse and beam widths, Rayleigh statistics describe the random nature of the magnitude of backscattered pressure. The statistics of speckle underlie the uncer...
Ultrasonic backscattering measurements by means of spatial averaging technique were carried out in steel to determine the ultrasonic attenuation coefficient. The attenuation coefficients were evaluated from the exponential decay of the backscattering signal. The results were compared with those obtained by evaluating the amplitude decay of the main pulse. Good agreement is observed provided the...
Poor fidelity invasive arterial blood pressure (IABP) traces are a frequent practical problem. It is common practice to describe any such trace as being 'damped'; the resonance behaviour of IABP measurement systems having been extensively described in the literature. However, as poor quality arterial blood pressure signals are seen even with optimal pressure transduction circuits, this cannot b...
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