نتایج جستجو برای: beam attenuation

تعداد نتایج: 160790  

2010
U. Vyas A. Payne N. Todd D. L. Parker R. B. Roemer D. A. Christensen

Introduction: MR-guided focused ultrasound surgery (MRgFUS) is a non-invasive means of causing selective tissue necrosis using high-power ultrasound and MR temperature imaging (MRTI). Predicting the power deposition pattern in the inhomogeneous tissue requires a beam propagation technique that has the ability to handle inhomogeneous acoustic properties. Beyond the innate inhomogeneities of tiss...

A. Shams, H. Shahbazian, M.A. Behrooz, M.J. Tahmasebi Birgani,

Background: Attenuation coefficient (μ) plays an important role in calculations of treatment planning systems, as well as determination of dose distributions in external beam therapy, dosimetry, protection, phantom materials and industry. So, its exact measurement or calculation is very important. The aim of this study was to evaluate the μ in different points in the water phantom anal...

2011
Jan K.H. Seppälä Jarmo A.J. Kulmala

The use of solid carbon fiber table materials in radiotherapy has become more common with the implementation of image-guided radiotherapy (IGRT), since the solid materials give less imaging artifacts than the so-called tennis racket couchtops. The downside of the solid carbon fiber couch inserts is that they increase the beam attenuation, resulting in increased surface doses and inaccuracies in...

2009
Hajime Fukuchi

The 21-GHz satellite broadcasting enables to transmit high-capacity information such as ultrahigh-definition TV, 3D-TV and so on. However, the 21.4 to 22.0-GHz band suffers from considerable rain attenuation. In order to compensate it, the studies about a rain fade mitigation techniques have been done. One of the techniques proposed by NHK Science and Technical Research Laboratories is an adapt...

Journal: :Journal of the Optical Society of America B 1996

Journal: :European Journal of Mechanics - A/Solids 2018

Journal: :International Conference on Aerospace Sciences and Aviation Technology 2007

Journal: :Journal of Ayub Medical College, Abbottabad : JAMC 2009
Saeed Ahmad Buzdar Muhammad Afzal Rao Aalia Nazir

BACKGROUND Photon beam is most widely being used for radiation therapy. Biological effect of radiation is concerned with the evaluation of energy absorbed in the tissues. It was aimed to analyse the depth dose characteristics of x-ray beams of diverse energies to enhance the quality of radiotherapy treatment planning. METHODS Depth dose characteristics of different energy photon beams in wate...

Journal: :Ultrasonics 2017
H Chen X P Li Y Y Chen G L Huang

In this study, a sandwich beam with periodic multiple dissipative resonators in the sandwich core material is investigated for broadband wave mitigation and/or absorption. An analytical approach based on the transfer matrix method and Bloch theorem is developed for both infinite and finite sandwich structures. Wave attenuation constants are theoretically obtained to examine the effects of vario...

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