نتایج جستجو برای: external environmental radiation
تعداد نتایج: 775132 فیلتر نتایج به سال:
Juvenile nasopharyngeal angiofibroma is a benign, vascular tumor which typically presents in adolescent males. Although surgical resection is usually recommended for the management of this tumor, external beam radiation therapy has also been advocated in the literature. We report three cases of large juvenile nasopharyngeal angiofibromas with extensive intracranial extension primarily managed w...
Background: The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area.Objective: A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of meas...
A canonical formalism is presented which allows for investigations of quantum radiation induced by localized, smooth disturbances of classical background fields by means of a perturbation theory approach. For massless, non-selfinteracting quantum fields at zero temperature we demonstrate that the low-energy part of the spectrum of created particles exhibits a non-thermal character. Applied to Q...
background: humans beings are continuously exposed to ionizing radiation from natural sources. the main contributors to natural radiation are high-energy cosmic radiation and radioactive nuclides that originates in the earth’s crust. exposure to high levels of radiation can cause serious health effects. in this study an attempt has been made to monitor the levels of environmental background rad...
Radiotherapy procedures fall into two main categories: external beam radiotherapy and brachytherapy. In external beam radiotherapy the radiation source is at a certain distance from the patient and the target within the patient is irradiated with an external radiation beam. In brachytherapy (see Chapter 13) radiation sources are placed directly into the target volume (intracavitary or interstit...
OBJECTIVES To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental, occupational, and medical diagnostic exposures. DESIGN Multinational retrospective cohort study of cancer mortality. SETTING Cohorts of workers in the nuclear industry in 15 countries. PARTICIP...
OBJECTIVES To identify profiles of children who did not properly use individual radiation dosimeters following Japan's 2011 Fukushima nuclear incident, and to assess how much error is generated by improper dosimeter use. PARTICIPANTS The participants in this study comprised 1637 school children who participated in the external radiation exposure screening programme administrated by Minamisoma...
Background: Natural radiation is constantly present in the environment and is emitted from a variety of natural and artificial sources. It affects human body and environment. Materials and Methods: The activity concentrations of 238U, 232Th and 40K have been determined by Gamma ray spectrometer with an HPGe detector in sediments of Cauvery River, Tamilnadu, India. Results: The absorbe...
The treatment of differentiated thyroid carcinoma (DTC) is surgery followed in some cases by adjuvant treatment, mostly with radioactive iodine (RAI). External beam radiotherapy (EBRT) is less common and not a well-established treatment modality in DTC. The risk of recurrence depends on three major prognostic factors: extra-thyroid extension, patient's age, and tumor with reduced iodine uptake....
Exposure to ionising radiation leads to a radiation dose. The main health effect of low levels of radiation dose is an increase in the chance of developing cancer. The radiation risk factor quantifies the level of risk caused by a given amount of radiation dose, i.e. there will be an X% risk of getting cancer per unit of dose received. This document provides an introduction to the risks from ex...
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