ABSTRACT
Contiene: resúmenes de los trabajos presentados en el evento referentes a diversos temas: normativa en protección radiológica, efectos biológicos de las radiaciones, aspectos socio-económicocs y docencia en protección radiológica, métodos y técnicas de protección radiológica. Contiene además: Reglamentos de protección radiológica (1980 y 1989); los requisitos del IPEN para licenciamiento; Instalación de fuentes de radiaciones ionizantes
Subject(s)
Radiation Protection/methods , X-Rays/education , Radiation, Ionizing/standardsABSTRACT
The dosimetry procedures to be used at electron energies, E0, below 15 MeV in order to determine absorbed dose to water with an ionization chamber have been investigated. The performance of different types of plane parallel ionization chambers was tested. A chamber suitable for use in accordance with the Nordic dosimetry recommendations was designed. Correction factors to be applied in order to use solid phantom materials instead of water were determined.
Subject(s)
Electrons , Radiation, Ionizing/standards , Radiometry/instrumentation , Energy Transfer , Evaluation Studies as Topic , Models, Biological , Models, Structural , Radiometry/methods , Radiometry/standards , Radiotherapy/methods , Radiotherapy Dosage , WaterABSTRACT
A sensitive and relatively simple method for obtaining an index of the spectral quality of high-energy x rays is presented. The method is based upon the use of photoactivation threshold detectors. Photonuclear reactions produce measurable amounts of radioactivity for radiation exposures of several thousand roentgens. Since the threshold energies for photonuclear reactions vary for different nuclei, the ratio of radioactivity induced in two appropriately selected foils is very sensitive to the x-ray spectrum. Photoactivation ratios (PAR) have been measured for 20-35-MV x rays using Co, Cu, Y, Zr, and Au activation foils. It is shown that the PAR method offers a sensitive and practical means for quality control of x-ray spectra, comparison of high-energy accelerators, and the measurement of variations of spectral quality control at different point in an irradiated volume.
Subject(s)
Radiation, Ionizing , Radiography/standards , X-Rays , Energy Transfer , Models, Theoretical , Physical Phenomena , Physics , Radiation, Ionizing/standards , Spectrum Analysis/methods , X-Rays/standardsABSTRACT
A sensitive and relatively simple method for obtaining an index of the spectral quality of x rays in the 4-15-MV range is presented. The method is based upon the simultaneous production of 115mIn by inelastic scattering of x rays by an indium foil and the production of 116mIn by neutron capture, where the neutrons are obtained from the photodisintegration of deuterium. Since the cross sections for the production of 115mIn and 116mIn have markedly different energy response functions, the ratio of radioactivities is very sensitive to the incident x-ray spectrum. Using a detector consisting of an indium foil sandwiched between two plastic bottles of D2O, photoactivation ratios (PAR) have been measured for 4-, 6-, and 10-MV x rays. It is shown that the PAR method offers a sensitive and practical means for quality control of x-ray spectra and comparison of high-energy accelerators.
Subject(s)
Radiation, Ionizing , X-Rays , Deuterium , Energy Transfer , Indium , Physical Phenomena , Physics , Radiation, Ionizing/standards , Scattering, Radiation , Spectrum Analysis/methods , X-Rays/standardsABSTRACT
In the United States it is common practice to calibrate Cobalt-60 teletherapy machines "in air," despite recommendations by the International Commission on Radiation Units and Measurements (ICRU) and other organizations that calibration be accomplished by measurement at 5-cm depth in a water phantom. A comparison has been made between the results of ionization measurements in air at 80.5-cm distance from the source and in water at 80-cm source-skin distance (SSD) for the determination of absorbed dose at three depth (5, 10, and 15 cm) for each of three fields sizes (6 X 6, 10 X 10, and 20 X 20 cm2), for a total of 42 Cobalt-60 machines. The mean of the ratio, absorbed dose from in-water measurements to absorbed dose at the same depth calculated from in-air measurements, ranged frt 5-cm depth for a 20 X 20-cm2 field size. Reasons for the differences are offered, and compliance with ICRU recommendations is suggested.
Subject(s)
Cobalt Radioisotopes , Gamma Rays/standards , Radiation, Ionizing/standards , Radioisotope Teletherapy/standards , Radiotherapy Dosage/standards , Air , Radioisotope Teletherapy/instrumentation , WaterABSTRACT
At its meeting in May-June 1975, the 15th Conference Generale des Poids et Mesures adopted two new special names of SI units; the becquerel, symbol Bq, equal to the second to the power minus one, s-1, for the quantity activity, and the gray, symbol Gy, equal to the joule per kilogram, J-kg-1, for absorbed dose and related quantities in the field of ionizing radiations. This action was preceded by a recommendation of the International Commission on Radiation Units and Measurements (ICRU) in 1974.
