نتایج جستجو برای: mass attenuation coefficient
تعداد نتایج: 679612 فیلتر نتایج به سال:
We present the assessment of ex vivo mouse muscle tissue by quantitative parametric imaging of the near-infrared attenuation coefficient µt using optical coherence tomography. The resulting values of the local total attenuation coefficient µt (mean ± standard error) from necrotic lesions in the dystrophic skeletal muscle tissue of mdx mice are higher (9.6 ± 0.3 mm(-1)) than regions from the sam...
The x-ray mass-attenuation coefficient of copper was measured at 108 energies between 5 and 20 keV using synchrotron radiation. The measurements are accurate to between 0.09 and 4.5 %, with most measurements being accurate to better than 0.12%. The imaginary component of the form factor of copper was also determined after subtracting the attenuation contribution due to scattering. Measurements ...
This paper presents a model for the characterization and selection of beeswaxes for use as base substitute tissue for the manufacture of objects suitable for external radiotherapy using megavoltage photon beams. The model of characterization was divided into three distinct stages: 1) verification of aspects related to the origin of the beeswax, the bee species, the flora in the vicinity of the ...
We reconsider the long-standing problem of accurate measurement of atomic form factors for fundamental and applied problems. We discuss the X-ray extended-range technique for accurate measurement of the mass attenuation coefficient and the imaginary component of the atomic form factor. Novelties of this approach include the use of a synchrotron with detector normalisation, the direct calibratio...
In an event detection application, sensor nodes measure signals that are emitted from multiple events and attenuated by the environment, and then collaborate to estimate the locations and magnitudes of the events. Existing event detection algorithms often assume that the number of the events is known in advance and/or the attenuation coefficient of the environment is given. This paper considers...
The propagation of slow compressional waves in air-saturated permeable solids was studied by experimental means between 10 and 500 kHz. The velocity and attenuation coefficient were measured as functions of frequency from the insertion delay and loss of airborne ultrasonic waves transmitted through thin slabs of 1-5 mm in thickness. Porous ceramics of 2-70 Darcy and natural rocks of 200-700 mDa...
The study described herein was undertaken to determine the role of proteins, in general, and collagen, in particular, in the observed absorption and speed of ultrasound in biological tissues. It had earlier been observed that ultrasonic absorption in tissues occurs at the macromolecular level, •'z though an additional contribution to attenuation arises from tissue structural features. a Each of...
In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perfo...
The aim of this paper was twofold: first, to present a virtual instrument for characterization of the cataract severity in the lens of the eye, based on the indirect measurements of ultrasound attenuation coefficient, second, to evaluate the instrument in vitro by assessment of measurement errors in case of the four different phantoms with a priory known characteristics (pure water, castor oil,...
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