نتایج جستجو برای: beam attenuation

تعداد نتایج: 160790  

Background & Aim: In mammography absorbed dose is insignificant. Biologically, in normal people, the phenomenon of hypersensitivity to low doses occurs. The purpose of this study was to investigate the synergistic of Single-Walled Carbon Nanotube (SWCNT) in the polymer substrate of Poly Dimethyl Siloxane (PDMS) in common energy in mammography. Materials & Methods: Cerium oxide nanoparticles an...

2002
J. C. Liu S. H. Rokni S. Roesler S. Taniguchi

Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick ste...

2006
W. Kenji Myint Malgorzata Niedbala David Wilkins Lee H. Gerig

Carbon fiber is commonly used in radiation therapy for treatment tabletops and various immobilization and support devices, partially because it is generally perceived to be almost radiotransparent to high-energy photons. To avoid exposure to normal tissue during modern radiation therapy, one must deliver the radiation from all gantry angles; hence, beams often transit the couch proximal to the ...

Ali Shabestani Monfared, Ali-Reza Shirazi Hamed Babapour Tayyeb Allahverdi Pourfallah

Introduction Superficial X-ray therapy is one of the most important treatment methods in radiotherapy especially in the treatment of superficial skin lesions (Up to 300 kVp). Quality of the X-ray beam that can be expressed by Half-Value Layer (HVL), are important indices for this type of treatment effective energy of photon and Homogeneity Coefficient (HC). Materials and Methods The HC of the s...

2011
Hans Norlander

How much do model errors influence the closed loop performance? This question is investigated for the control problem of designing active damping of vibrations in a viscoelastic cantilever beam. The beam is physically modeled using Fourier transformed Euler-Bernoulli beam equations. For control design the standard LQG technique is employed, and two different finite order models are used. One is...

2001
C. I. ZANELLI

The requirements for beamforming in high intensity focused ultrasound (HIFU) for tissue destruction are substantially different than those for diagnostic imaging. High numerical aperture and CW efficiency are desirable for tissue destruction, while depth of focus and broadband sensitivity are key to good imaging. When the same transducer must be used for ablation and imaging some compromises mu...

Journal: :Journal of the Optical Society of America. A, Optics, image science, and vision 2001
K E Oughstun

The asymptotic description of the coupled spatial and temporal evolution of a pulsed ultrawideband electromagnetic beam field as it propagates through a dispersive, attenuative material that occupies the half-space z > or = z(0) is obtained from the angular spectrum of plane waves representation. This angular-spectrum representation expresses the wave field as a superposition of both homogeneou...

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