نتایج جستجو برای: mass attenuation coefficient

تعداد نتایج: 679612  

2015
Manoj Kumar Gupta Gurinderjeet Singh Shilpa Rani Amrit Singh

The linear attenuation coefficient of some commonly available protein rich pulses

Introduction: Globally, the need for radiotherapy as a part of cancer management increases every year. Thus, the shielding for megavoltage radiotherapy rooms is of great importance. Materials and Methods: In the present study, 14 types of developed high-density concrete with densities ranging from 2.45 to 5.11 were simulated by using Monte Carlo method. The linear attenuation coefficient and t...

2002

We read with interest the recent paper by Shiga et al. published in the European Journal of Nuclear Medicine [1]. The authors report some interesting results concerning the effect of triple-energy window-based scatter correction on brain perfusion SPET using statistical para-metric mapping (SPM) analysis. The research performed is worthwhile and contributes significantly to our understanding of...

2013
Salah I. Yahya

In this paper, a one-port time-domain/frequencydomain based technique using a short-circuited coaxial geometry inserted vertically in a liquid tank is designed and presented as a multi-level storage tank gauge and monitor. For storage tanks of small physical liquid levels, the attenuation inside the coaxial cable sensor may be neglected and both the physical liquid levels and liquid permittivit...

2015
Yuya Nakamura Seiji Tomiguchi Masayuki Tanaka

BACKGROUND Generally, attenuation correction is made by incorporating a linear attenuation coefficient, which is based on the attenuation coefficient map (mu-map) created from a computed tomography scan, into the ordered subsets-expectation maximization reconstruction method in non-uniform domains. A non-uniform Chang's attenuation correction method that uses the mu-map created from a computed ...

Journal: :Ultrasound in medicine & biology 2007
Linda R Taggart Ralph E Baddour Anoja Giles Gregory J Czarnota Michael C Kolios

High frequency ultrasound imaging (20 to 60 MHz) is increasingly being used in small animal imaging, molecular imaging and for the detection of structural changes during cell and tissue death. Ultrasonic tissue characterization techniques were used to measure the speed of sound, attenuation coefficient and integrated backscatter coefficient for (a) acute myeloid leukemia cells and corresponding...

2006
Eugenio Gorgucci Luca Baldini

Although is not a major error source at C-band, attenuation may degrade the radar measurement to a considerable degree in situations like a precipitation event in the radar shadow of a strong convective cell, or may affect precipitation accumulation estimates at distances far from the radar site. For C-band radars, attenuation can be corrected using different methods depending on the type of me...

2013
Sheng-Kai Tsao Jenho Tsao

In a previous work, we developed a consistent TAC (tissue attenuation coefficient) estimator using bubble echoes. Based on temporal averaging, we can improve the estimation precision of TAC for the tissue bounded between two vessels. In this paper, we extend it to use frequency diversity for saving interrogation time by transmit multiple narrowband signals in each pulse. At first, we analyze th...

2014
Nicholas Dwork Uzair Sikora

Optical Coherence Tomography (OCT) is an interferometric medical imaging technique that acquires depth information from a biological sample. For a single point on the surface, OCT records the amount of light reflected from each depth; one line of information is called an A-scan. The amount of light reflected back is a function of a physical parameter called the attenuation coefficient, denoted ...

2018
T. M Jordan J. L. Bamber C. N Williams J. D Paden M. J. Siegert P Huybrechts Olivier Gagliardini F Gillet-Chaulet T. M. Jordan C. N. Williams J. D. Paden P. Huybrechts O. Gagliardini F. Gillet-Chaulet

Radar inference of the bulk properties of glacier beds, most notably identifying basal melting, is, in general, derived from the basal reflection coefficient. On the scale of an ice sheet, unambiguous determination of basal reflection is primarily limited by uncertainty in the englacial attenuation of the radio wave, which is an Arrhenius function of temperature. Existing bed-returned power alg...

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