نتایج جستجو برای: glandular absorbed dose
تعداد نتایج: 332419 فیلتر نتایج به سال:
abstract background: accurate methods of radiation therapy dose calculation. there are different monte carlo codesfor simulation of photons, electrons and the coupled transport of electrons and photons. mcnpis a general purpose monte carlo code that can be used for electron, photon and coupledphoton-electron transport.monte carlo simulation of radiation transport is considered to be one of the ...
BACKGROUND The goal of this prospective study was to estimate the absorbed (radiation) doses to salivary glands in radioiodine therapy of thyroid cancer under chewing-gum stimulation using (124)I positron emission tomography (PET)/computed tomography (CT) imaging. METHODS Duplex ultrasonography was conducted in three test persons for visual comparison of the glandular blood flow with three di...
Background: Average glandular dose (AGD), entrance skin air kerma (ESAK) and normalized glandular dose (DgN) are the main dosimetric quantities in mammography. Breast tissue composition is one of the factors affecting on DgN values. In this study both homogeneous and heterogeneous breast tissue is assumed and its impact on DgN values are evaluated. Methods: Homogeneous breast phantom with diffe...
background marketing new radiography devices necessitates documenting their absorbed x-ray doses. since the current literature lacks studies on new devices, we assessed the doses of two new devices that had not previously been assessed. objectives the new devices were compared to the promax three dimensional (3d) scanner at two fields of view (fov) in nine critical head and neck tissues and org...
background: the natural radionuclides are always present in soil and care needs to be taken to minimize the radiation dose to humans. these radionuclides are mostly gamma ray emitting radionuclides which contribute to the radiation dose in long term behavior of radionuclides in soil. health hazards associated with natural radioactivity are of great concern and it is necessary to assess risk due...
Our purpose in this study was to investigate the image quality and absorbed dose characteristics of a digital mammography imaging system with a CsI scintillator, and to identify an optimal x-ray tube voltage for imaging simulated masses in an average size breast with 50% glandularity. Images were taken of an ACR accreditation phantom using a LORAD digital mammography system with a Mo target and...
background: natural radioactivity in materials under certain conditions can reach the hazardous radiological levels. so, it becomes necessary to study the natural radioactivity in different materials to assess the dose for the population in order to know the health risks and to have a baseline for future changes in the environmental radioactivity due to human activities. materials and methods: ...
introduction: skin dose and depth dose distribution of some beta sources that can contaminate skin or protective clothing covering the skin have been calculated using varskin2. materials and methods: in this research, absorbed dose to skin and depth dose from the skin surface have been calculated for 90sr/90y, 147pm, 32p beta emitter radioisotopes by using input parameters: activity of source, ...
introduction evaluation of the delivered dose of externally wedged photon beams by external diode dosimeters during the treatment process requires the estimation of exit surface dose correction factors in various wedge angles and field sizes. materials and methods a system of absorbed dose evaluation, using p-type diode dosimeters placed on the exit surface of a phantom, was characterized for e...
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