نتایج جستجو برای: ray
تعداد نتایج: 302977 فیلتر نتایج به سال:
introduction: inappropriate condensation of gutta-percha or improper use of sealer can lead to voids in root canal filling material and consequent failure of the treatment. timely detection of voids within root canal filling may prevent complications. in this study, we compared the accuracy of digital and conventional radiograph for detecting voids within root canal fillings . materials & metho...
conclusions headache, seizure, and trauma are the main reasons for ct scan requests. about 12% of the brain ct scans were abnormal. being knowledgeable about the indications of imaging, unnecessary imaging can be prevented, and consequently, its risks can be minimized. patients and methods in the present case series, demographic information and ct scan reports of 167 patients referred to taba r...
conclusion the cv value correlated more closely with low lvef and more accurately indicated an enlarged heart than ca or ctr. this may be due to the fact that an anteroposterior measurement of heart size is included in the former but not the latter two measurements. these study results may help quantify left heart enlargement with greater accuracy than may be obtained from standard cxr. backgro...
introduction quality control (qc) techniques are used in monitoring and maintenance of the components of an x-ray system. qc of radiology devices plays a significant role in reduction of medication dose and optimization of image quality. this study aimed to conduct qc tests on randomly selected radiology devices, installed in diagnostic imaging departments of iran. materials and methods in tota...
osteoma is a benign, slow-growing osteogenic tumor that sometimes arises from the craniomaxillofacial region, such as the sinus, temporal or jaw bones. osteoma consists of compact or cancellous bone that may be peripheral, central or extraskeletal type. peripheral osteoma arises from the periosteum and is commonly a unilateral, pedunculated mushroom-like mass. peripheral osteoma of the mandible...
background: medical x-rays are the largest man-made source of public exposure to ionizing radiation. it is important to avoid conditions where the amount of radiation used is more than that needed for the procedure. materials and methods: the entrance skin exposure (ese) measurement was conducted for quality control of x-ray machines and survey of operator’s experimental techniques. the eses we...
introduction in radiography, dose and image quality are dependent on radiographic parameters. the problem is caused from incorrect use of radiography equipment and from the radiation exposure to patients much more than required. therefore, the aim of this study was to implement a quality-control program to detect changes in exposure parameters, which may affect diagnosis or patient radiation do...
از زمانی که کمپلکس های فلزی شامل لیگاند های چهاردندانه با الکترون های غیرمستقرشان به عنوان هدایت کننده های خوبی معرفی شدند، شیمی کئوردیناسیون کمپلکس های فلز های واسطه پلی کربوکسیلات آروماتیک در شیمی معدنی، مورد توجه فراوان قرار گرفته است. در این کار ما سنتز کمپلکس های فلزهای واسطه (آهن و کبالت) از واکنش 1و2و4و5 -بنزن تترا کربوکسیلیک و آمین آلیفاتیک در آب را گزارش دادیم. این ترکیبات با استفاده ...
In 2012 it was forty years ago that the discovery of the first X-ray binary Centaurus X-3 became known. That same year it was discovered that apart from the High-Mass X-ray Binaries (HMXBs) there are also Low-Mass X-ray Binaries (LMXBs), and that Cygnus X-1 is most probably a black hole. By 1975 also the new class of Be/X-ray binaries was discovered. After this it took 28 years before ESAs INTE...
Here, we investigate the possible optical anisotropy of vacuum due to gravitational field. In doing this, we provide sufficient evidence from direct coordinate integration of the null-geodesic equations obtained from the Lagrangian method, as well as ray-tracing equations obtained from the Plebanski’s equivalent medium theory. All calculations are done for the Schwarzschild geometry, which resu...
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