ABSTRACT
The paper outlines the specific features of using microwave technologies in dental and eye prostheses designed in Russia in 1992-1998. Thermal, microwave, and combined polymerizations of plastic materials used in prosthesis are compared. A Denta microwave unit is presented, which realizes a combined microwave technology.
Subject(s)
Dental Prosthesis , Eye, Artificial , Microwaves , Hot Temperature , Humans , Models, Theoretical , PolymersABSTRACT
Polymerization of basic acrylic heat-hardened plastic under the effect of UHF exposure is studied. Specimens and standard bases of dentures from Russian acrylic plastic widely used in orthodontics were used in experiment. Plastics polymerized in UHF field and in water bath were compared. Experiments helped develop a method for making removable dentures using microwaves.
Subject(s)
Denture Bases , Denture, Complete , Microwaves , Technology, Dental/methods , Acrylic Resins , Aged , Denture Design/methods , Female , Humans , Male , Mandible , Maxilla , Mechanics , Middle AgedABSTRACT
An approach for evaluating the influence of measurement geometry on estimates of 131(I) in the thyroid from measurements with survey meters was developed using Monte Carlo simulation of radiation transport in the human body and the radiation detector. The modified Monte Carlo code, EGS4, including a newly developed mathematical model of detector, thyroid gland, and neck, was used for the computations. The approach was tested by comparing calculated and measured differential and integral detector characteristics. This procedure was applied to estimate uncertainties in direct thyroid-measurement results due to geometrical errors.
Subject(s)
Iodine Radioisotopes/metabolism , Thyroid Gland/diagnostic imaging , Adolescent , Adult , Child , Child, Preschool , Humans , Models, Biological , Monte Carlo Method , Phantoms, Imaging , Radionuclide ImagingABSTRACT
Radioiodine released to the atmosphere from the accident at the Chernobyl nuclear power station in the spring of 1986 resulted in large-scale thyroid-gland exposure of populations in Ukraine, Belarus, and Russia. Because of the short half life of 131I (8.04 d), adequate data on the intensities and patterns of iodine deposition were not collected, especially in the regions where the incidence of childhood-thyroid cancer is now increasing. Results are presented from a feasibility study that show that accelerator-mass-spectrometry measurements of 129I (half life 16 x 106 y) in soil can be used to reconstruct 131I-deposition density and thus help in the thyroid-dosimetry effort that is now urgently needed to support epidemiologic studies of childhood-thyroid cancer in the affected regions.
