نتایج جستجو برای: ray ct dose
تعداد نتایج: 689623 فیلتر نتایج به سال:
exposure to radiation from different types of television sets was measured to ascertain the levels of hazards posed to the human biological system. measurement of the annual radiation dose hazards was performed using a halogen-quenched gm tube with thin mica end window having a density of 1.5 mg/cm2, effective window diameter of 0.360 inch and side wall of 0.012 inch thick. the gm tube was plac...
background: the radiation doses resulting from diagnostic x-ray examinations are routinely measured in terms of entrance surface dose (esd) and effective dose (ed). in this study, for the purpose of radiation protection, the radiation doses received from digital chest x-ray examination were evaluated in terms of esd and ed. material and methods: the ed was calculated by using the mcnp monte car...
the purpose of the research was determine the effects of gamma ray on seed germination, seedling height and root length of rice (oryza sativa l. spp. indica cv. mr219) to identify the lethal dosage of the radiation. paddy seeds of mr219 were exposed to different doses of gamma radiations viz 50,100,150,200,250,300,350,400,450,500,600,700,800,900 and 1000 gy using 60co as the radiation source. t...
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 high doses of ionizing radiation can lead to adverse health outcomes such as cancer induction in humans. although the consequences are less evident at very low radiation doses, the associated risks are of societal importance. this study aimed at assessing entrance skin doses (esds) in patients undergoing selected diagnostic x-ray examinations at public hospitals of akwa ibom state,...
background: pregnant women are sometimes exposed to ionizing radiation in radiology examinations for various reasons. in such cases, the radiation dose to the conceptus and subsequent risks should be estimated. objective: the purpose of this study was the calculation and presentation of fetal dose and subsequent risks resulted from different x-ray examinations. materials and methods: an analyti...
One of the most widely used diagnostic devices in medical imaging is computed tomography scanning with the use of X-ray ionization. After years of using this tool in the diagnosis and treatment, external doses of these beams can pose a risk of secondary cancer, which is significant in terms of radiation safety and protection. In this paper, using the Monte Carlo code MCNPX2.6 performed over thr...
abstract background: the x-ray machines used for radiodiagnosis should meet certain quality assurance (qa) programmes . these are necessary to have good quality radiographs at reasonably low exposure to patients. materials and methods: dose reduction methods in abdomen x-ray examination were carried out in 10 hospitals in tehran. this paper presents the work, which was implemented on 200 pa...
Dosimetric comparison of carbon ion and X-ray radiotherapy for Stage IIIA non–small cell lung cancer
The present study compared the dose-volume histograms of patients with Stage IIIA non-small cell lung cancer (NSCLC) treated with carbon ion radiotherapy with those of patients treated with X-ray radiotherapy. Patients with Stage IIIA NSCLC (n = 10 patients for each approach) were enrolled. Both radiotherapy plans were calculated with the same targets and organs at risk on the same CT. The trea...
Characterization and Optimization of Silicon-strip Detectors for Mammography and Computed Tomography
The goal in medical x-ray imaging is to obtain the image quality required for a given detection task, while ensuring that the patient dose is kept as low as reasonably achievable. The two most common strategies for dose reduction are: optimizing incident x-ray beams and utilizing energy information of transmitted beams with new detector techniques (spectral imaging). In this thesis, dose optimi...
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