نتایج جستجو برای: photon attenuation coefficient

تعداد نتایج: 284445  

Journal: :Communications in numerical methods in engineering 2009
Hengyong Yu Jiansheng Yang Ming Jiang Ge Wang

Single photon emission computed tomography (SPECT) is an important biomedical imaging modality. However, since gamma cameras are expensive and bulky, truncated projection data are either preferred or unavoidable. Inspired by the recent results on interior tomography in the x-ray CT field, here we present the interior SPECT approach for exact and stable reconstruction of a region of interest (RO...

2012
R. M. V. Silva D. N. Souza

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 ...

Journal: :journal of solid mechanics 0
r kumar department of mathematics, kurukshetra university kurukshetra-136119, haryana , india p sharma department of mathematics, kurukshetra university kurukshetra-136119, haryana , india

in this paper the propagation of harmonic plane waves in a homogeneous anisotropic magneto-piezothermoelastic diffusive body with fractional order derivative is studied. the governing equations for a homogeneous transversely isotropic body in the context of the theory of thermoelasticity with diffusion given by sherief et al. [1] are considered as a special case. it is found that three types of...

Journal: :Journal of Materials Science: Materials in Electronics 2021

Penta-glasses with a 59B2O3–29SiO2–2LiF–( $$10-x$$ ) ZnO– $$x$$ TiO2 composition the melt-quench techniques were prepared. X-ray diffraction was used to examine nature of fabricated glasses. The changes in structure glasses studied by Fourier-transform infrared spectroscopy spectra. molar volume reduces as density increases. mechanical characteristics these evaluated. Besides, for glasses, Phy-...

Dariyush Shahbazi-Gahrouei Ehsan Khodamoradi Kourosh Ziaie Zahra Shahi

  Introduction:  The use of radioactive iodine (131I) has become an important adjunct to the treatment of thyroid cancer and hyperthyroidism. Salivary gland has the ability to concentrate radioactive iodine under normal circumstances. Salivary gland dysfunction and dry mouth are the common side effectsof high-dose radioiodine therapy. The purposeof this stu...

Journal: :Annals of nuclear medicine 2005
Jingming Bai Jun Hashimoto Koichi Ogawa Atsushi Kubo Atsushi Fukunaga Satoshi Onozuka Koichi Uchida

OBJECTIVE The aim of this study was to evaluate the effect of scatter and attenuation correction in region of interest (ROI) analysis in brain perfusion single-photon emission tomography (SPECT) and to assess the influence of selecting the reference area on semi-quantification. METHODS Ten normal subjects were enrolled and injected with 123I-iodoamphetamine to undergo simultaneous emission an...

Journal: :iranian journal of radiation research 0
a. vahidian kamyad department of mathematic, ferdowsi university, mashad, iran m.h. noori eskandari department of mathematic, ferdowsi university, mashad, iran m. naji midani department of medical physics, mashad university for medical sciences, mashad, iran m. hajizadeh saffar department of medical physics, mashad university for medical sciences, mashad, iran

background: photon attenuation as an inevitable physical phenomenon influences on the diagnostic information of spect images and results to errors in accuracy of quantitative measurements. this can be corrected via different physical or mathematical approaches. as the correction equation in mathematical approaches is nonlinear, in this study a new method of linearization called ‘piece wise line...

Introduction: This study aimed to evaluate the efficacy of a synthesized bolus in the reduction of damage to body tissues and the protection of the organ at risk (OAR) in radiotherapy application. Several properties of the synthesized bolus, including density, transmission factor, and effective mass attenuation coefficient, were investigated. Material and ...

Journal: :iranian journal of nuclear medicine 2006
mohsen bakhshandeh hossein rajabi masoud vafamanesh ali akbar sharafi shahram seifollahi

introduction: nowadays, imaging of the myocardial perfusion (mpi) using the single photon emission tomography (spet) in the diagnosis of coronary artery disease, especially myocardial ischemia, is of great importance. in contrast to the coronary artery angiography, mpi is non-invasive, less expensive and more physiological. unfortunately, this image is affected by the some artifacts. these arti...

Journal: :iranian journal of radiation research 0
m.j. tahmasebi birgani medical physics department, jondi shapour university of medical sciences, ahwaz, iran m.a. behrooz medical physics department, jondi shapour university of medical sciences, ahwaz, iran h. shahbazian radiation therapy department, golestan hospital, jondi shapour university of medical science, ahwaz, iran a. shams medical physics department, jondi shapour university of medical sciences, ahwaz, iran

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 analytically ...

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