نتایج جستجو برای: the attenuation parameters
تعداد نتایج: 16108098 فیلتر نتایج به سال:
Monte Carlo calculation of shielding parameters for fast neutrons in newly developed heavy concretes
Introduction: The role of radiotherapy as a part of cancer management increases every year around the world. Thus, Radiation protection in the design of radiotherapy rooms are of great importance. Materials and Methods: In present study using Monte Carlo method, MCNPX code, fourteen types of developed high density concretes with densities ranging from 2.45 ...
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...
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...
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...
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 ...
Many ultrasonic parameters, primarily related to attenuation and scatterer size, have been used to characterize the composition of atherosclerotic plaque tissue. In this study, we combine elastographic (axial strain ratio) and ultrasonic tissue characterization parameters, namely the attenuation coefficient and a scattering parameter associated with an "equivalent" scatterer size to delineate b...
the introduction of ex vivo lung perfusion (evlp) in the practice of lung transplantation has allowed the reconditioning of the marginal grafts and their conversion into transplantable grafts. in addition, evlp can provide a platform for the application of various preventive measures to decrease the incidence of post-transplant complications. while the toronto team targets the attenuation of th...
introduction: we aimed to investigate the effect of right bundle branch block (rbbb) on perfusion and functional parameters in dipyridamole stress/rest tc99m-mibi gated myocardial perfusion spect (gspect) which may be helpful in interpretation of myocardial perfusion imaging. methods: we studied 73 patients with low pre-test likelihood of coronary artery disease in two groups: 38 patients with...
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