نتایج جستجو برای: kerma
تعداد نتایج: 466 فیلتر نتایج به سال:
Brachytherapy describes a process where radioactive sources are inserted directly into the target area of a patient to treat disease. Before they can be used for treatment, brachytherapy sources must be calibrated such that medical physicists know their exact air kerma strength a quantity given by manufacturers as a standard. Each individual source must be measured before use. Therefore, medica...
Th is study uses a bioarchaeological approach to examine the cultural and biological relationships between two groups who lived in ancient Nubia during the Bronze Age, C-Group and Kerma. While archaeological evidence indicates that these groups show many cultural similarities, refl ections of behaviors such as pottery use and mortuary practices suggest that C-Group and Kerma displayed their eth...
The aim of this study was to compare the high dose rate (HDR) iridium 192 source calibration in terms of reference air kerma rate with two types of ionisation chambers (a thimble chamber and a well-type chamber). Dose measurements in water have been also performed with thimble chamber and thermoluminescent dosimeters (TLD) in order to validate the absorbed dose to water calculation provided by ...
The aim of this study was to perform a detailed analysis of the air kerma values around a Liac mobile linear accelerator working in a conventional operating room (OR) for IORT. The Liac delivers electron beams at 4, 6, 8 and 10 MeV. A radiation survey to determine photon leakage and scatter consisted of air kerma measurements on a spherical surface of 1.5 m radius, centered on the titanium exit...
Mammography, using X-rays, is routinely utilized for screening of patients for prevention of breast cancer. Nevertheless, there is a small but significant risk of radiation induced carcinogenenesis associated with radiation exposure of the breast, being glandular tissue the most sensitive one among the tissues composing breast. Risk estimation in mammography may be determined by the mean absorb...
Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the compari...
Monte Carlo calculations are frequently used to analyse a variety of radiological science applications using low-energy (10-1000 keV) photon sources. This study seeks to create a low-energy benchmark for the MCNP Monte Carlo code by simulating the absolute dose rate in water and the air-kerma rate for monoenergetic point sources with energies between 10 keV and 1 MeV. The analysis compares four...
BACKGROUND The frequency of complex percutaneous coronary interventions (PCIs) has increased in the last few years, with a growing concern on the radiation dose received by the patients. Multicenter data from large unselected populations on patients' radiation doses during coronary angiography (CA) and PCI and temporal trends are lacking. This study sought to evaluate the temporal trends in pat...
The air-kerma standards used for the measurement of medium-energy x rays were compared at the National Institute of Standards and Technology (NIST) and at the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and two NIST reference-class transfer ionization standards. Reference beam qualities...
A comparison has been made of the air-kerma standards for medium-energy x-rays of the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and three NIST reference-class transfer ionization chamber standards. Reference beam qualities ...
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