نتایج جستجو برای: kerma
تعداد نتایج: 466 فیلتر نتایج به سال:
ACR American College of Radiology, CRCPD Conference of Radiation Control Program Directors, FDA Food and Drug Administration, ICRU International Commission on Radiation Units and Measurements, IEC International Electrotechnical Commission, IRP interventional reference point, Ka,r total air kerma at the interventional reference point, NCRP National Council on Radiation Protection and Measurement...
OBJECTIVE To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. MATERIALS AND METHODS Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the...
The purpose of this work was to develop a method for easily verifying that the activity or air kerma strength of pre-assembled eye plaques, used in the treatment of ocular melanomas, agrees with the activity or air kerma strength called for in the treatment plan. A Capintec CRC-7 Dose Calibrator with its standard vial/syringe sample holder was used to measure the activity of pre-assembled COMS ...
Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray referenc...
In this study, a procedure to test the linear reference air kerma rate of 192Ir wires using a well-type chamber is described. The method is based on a special lead insert with a 1 cm acrylic aperture that provides a differential response of the well chamber. The wire is considered divided into 1 cm parts. Using an external positioning system it is possible to place every part of the wire at the...
Conventional diagnostic X-ray units are used for radiographic imaging in many countries. For obtaining entrance surface doses, a numerical dose determination method has been applied in Japan. Although this technique is effective, it has to account for errors, particularly fluctuations, due to the beam quality and output of X-ray tubes. As a part of our quality control procedures, we recorded th...
A direct comparison was made between the air kerma primary standards used for the measurements of low-energy x rays at the National Institute of Standards and Technology (NIST) and the National Physical Laboratory (NPL). The comparison was conducted at the NPL using NPL reference radiation qualities between 10 kV and 80 kV. The results show the primary air-kerma standards to agree within 0.6 % ...
The advent of high energy neutron radiotherapy will require the neutron cross-section data and kerma factors for elements of biomedical importance to be extended up to and possibly above 50 MeV. Nuclear model calculations have been employed to produce a set of neutron cross-sections for C, N and O from 20 to 50 MeV. The strategy employed involves the optical model fitting of experimental total ...
OBJECTIVE: To develop a double-faced plane-parallel ionization chamber for measurement of air kerma and air kerma rate in X-radiation fields utilized in conventional radiography and mammography. MATERIALS AND METHODS: The chamber has entrance windows made of aluminized polyester film, inner and guard electrodes of aluminum at one side (face A) and graphite at the other side (face G). The presen...
OBJECTIVES The authors sought to compare the radiation dose between radial and femoral access. BACKGROUND Small trials have shown an increase in the radiation dose with radial compared with femoral access, but many were performed during the operators' learning curve of radial access. METHODS Patients were randomized to radial or femoral access, as a part of the RIVAL (RadIal Vs. femorAL) tr...
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