نتایج جستجو برای: photon attenuation

تعداد نتایج: 118713  

Journal: :Journal of physics 2023

Abstract In order to clarify the distribution law of ultraviolet photon field in gas insulated switchgear busbar, meanwhile correct detection range sensor, optical model busbar based on uniform theory diffraction is proposed ray tracing. distributions radiation fields are calculated when partial discharge occurs at key positions such as basin insulator and conductor. Based average irradiance, m...

1999
V. V. Vassiliev

Recent observations of the TeV γ-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the spectral energy density (SED) of extragalactic background light (EBL) which causes attenuation of TeV photons via pair-production when they travel cosmological ...

Journal: :Medical physics 2014
Daniel H Paulus Daniela Thorwath Holger Schmidt Harald H Quick

PURPOSE Multimodality imaging has become an important adjunct of state-of-the-art radiation therapy (RT) treatment planning. Recently, simultaneous PET/MR hybrid imaging has become clinically available and may also contribute to target volume delineation and biological individualization in RT planning. For integration of PET/MR hybrid imaging into RT treatment planning, compatible dedicated RT ...

2007
Cheng-Ling Kuo A. B. Chen Y. J. Lee L. Y. Tsai R. K. Chou R. R. Hsu H. T. Su L. C. Lee S. A. Cummer H. U. Frey S. B. Mende Y. Takahashi H. Fukunishi

[1] The ISUAL experiment on the FORMOSAT-2 satellite has confirmed the existence of ionization and Lyman-Birge-Hopfield (LBH) band emissions in elves. In this paper, an in-depth study of the ISUAL recorded elves was carried out. Numerical simulation results of elves based on an electromagnetic finite difference time domain (FDTD) model of the emissions between 185–800 nm and of their spatial-te...

Journal: :The American journal of physiology 1998
Angelo Pietrobelli Zimian Wang Carmelo Formica Steven B Heymsfield

Dual-energy X-ray absorptiometry (DXA) is rapidly gaining acceptance as a reference method for analyzing body composition. An important and unresolved concern is whether and to what extent variation in soft tissue hydration causes errors in DXA fat estimates. The present study aim was to develop and validate a DXA physical hydration model and then to apply this model by simulating errors arisin...

Journal: :Optics express 2012
Xiao-song Ma Sebastian Kropatschek William Naylor Thomas Scheidl Johannes Kofler Thomas Herbst Anton Zeilinger Rupert Ursin

We present a high-fidelity quantum teleportation experiment over a high-loss free-space channel between two laboratories. We teleported six states of three mutually unbiased bases and obtained an average state fidelity of 0.82(1), well beyond the classical limit of 2/3. With the obtained data, we tomographically reconstructed the process matrices of quantum teleportation. The free-space channel...

Journal: :Physics in medicine and biology 2012
Gengsheng L Zeng Grant T Gullberg

In single-photon emission computed tomography (SPECT), projection data can be truncated when the camera's field of view is smaller than the object to be imaged. Using truncated projections to reconstruct a region of interest (ROI) is a reality we must face if small detectors are used. The truncated data result in an underdetermined system of imaging equations, which may lead to non-unique solut...

Journal: :Circulation 1991
R O Bonow D S Berman R J Gibbons L L Johnson J A Rumberger M Schwaiger F J Wackers

T his statement of the Committee on Advanced Cardiac Imaging and Technology of the Council on Clinical Cardiology addresses the use of positron emission tomography (PET) as a clinical tool for the diagnosis and management of patients with coronary artery disease. Over the past decade PET technology has evolved to the point that clinical PET studies can be performed safely and efficiently in the...

Journal: :Circulation 2013
Hirofumi Koike Eijun Sueyoshi Yasuo Kido Hiroki Nagayama Ichiro Sakamoto Masataka Uetani Takashi Kudo Satoshi Ikeda

A 68-year–old woman had been experiencing Raynaud symptom, palpitation of the heart, and short breath in walking stairs or slopes for 7 years. Recently, these symptoms had rapidly become worse. She admitted to our hospital. At that time, she was diagnosed with systemic scleroderma (limited scleroderma). Pulmonary hypertension was pointed out by echocardiography (estimated pulmonary artery press...

Journal: :Journal of neurology, neurosurgery, and psychiatry 1997
T J Germon P E Evans N J Barnett T T Lewis P Wall R J Nelson

OBJECTIVE To develop an in vivo model for testing spatially resolved spectroscopy and quantified near infrared spectroscopy (NIRS) cerebral blood flow measurements. METHOD Multiple detector NIRS has been used to study changes in tissue oxyhaemoglobin (O2Hb) concentration during selective internal carotid angiography. A significant reduction in O2Hb occurred in tissue interrogated by detectors...

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