ABSTRACT
The main objective of this work is to simulate the X-ray scattered spectra by different pediatric phantoms (simulation of children subjected to barium meal procedures) to calculate an energy correction factor (ECF) to the reading of thermoluminescent dosimeters (TLDs). To perform this evaluation, the TLDs were positioned over three areas in two occupational workers: eyes, thyroid and hands. The Geant4 toolkit was used to define the spectra collected by TLDs, making possible to calculate the ECF. This work was developed in two stages: (1) evaluation of scattered spectra by different standard phantoms (newborn, 1, 5 and 10 years old); (2) definition of the ECF to the absorbed energy by each TLD. Geant4 shows to be a good toolkit to calculate the ECF and among the different characteristics evaluated, in this work, the TLD position and acceleration voltages are the most significant parameters that may influence the ECF calculated.
Subject(s)
Occupational Exposure/analysis , Pediatrics/methods , Radiation Exposure , Thermoluminescent Dosimetry/instrumentation , Barium Sulfate/administration & dosage , Child , Child, Preschool , Eye/radiation effects , Fluoroscopy , Hand/radiation effects , Humans , Infant , Infant, Newborn , Monte Carlo Method , Phantoms, Imaging , Scattering, Radiation , Thyroid Gland/radiation effectsABSTRACT
This work presents the results of radon concentration measurements of construction materials used in the Brazilian industry, such as clay (red) bricks and concrete blocks. The measurements focused on the detection of indoor radon activity during different construction stages and the analysis of radionuclides present in the construction materials. For this purpose, sealed chambers with internal dimensions of approximately 60×60×60 cm3 were built within a protected and isolated laboratory environment, and stable air humidity and temperature levels were maintained. These chambers were also used for radon emanation reduction tests. The chambers were built in four major stages: (1) assembly of the walls using clay (red) bricks, concrete blocks, and mortar; (2) installation of plaster; (3) finishing of wall surface using lime; and (4) insulation of wall surface and finishing using paint. Radon measurements were performed using polycarbonate etched track detectors. By comparing the three layers applied to the masonry walls, it was concluded that only the last step (wall painting using acrylic varnish) reduced the radon emanation, by a factor of approximately 2. Samples of the construction materials (clay bricks and concrete blocks) were ground, homogenized, and subjected to gamma-ray spectrometry analysis to evaluate the activity concentrations of 226Ra, 232Th and 40K. The values for the index of the activity concentration (I), radium equivalent activity (Raeq), and external hazard index (Hext) showed that these construction materials could be used without restrictions or concern about the equivalent dose limit (1 mSv/year).
ABSTRACT
Since the earliest works proposing the use of protons for imaging, the main advantage of protons over X-rays was expected to be a result of the specific property of the proton flux dropping off very steeply at the end of the particle range. This idea was declared but was not checked. In the present work, this assumption was investigated using the Monte Carlo simulation for the case of registration of protons with a thin detector.
