ABSTRACT
Gadolinium has been recently proposed, as neutron capture agent in NCT (Neutron Capture Therapy), due to both the nuclide high neutron capture cross section, and the remarkable selective uptake inside tumour tissue that Gd-loaded compounds, can provide. When a neutron external source is supplied, different Gd nuclear reactions, and the generated Auger electrons in particular, cause a high local energy deposition, which results in a tumour cell inactivation. Preliminary micro- as well as macrodosimetric Monte Carlo computational investigations show that the tumour-to-healthy tissue biological damage ratio is in close relation to the neutron beam energy spectrum. The results points out that the optimum neutron spectrum, to be used for Gd-NCT, seems to lie in the 1 to 10 keV energy range. In order to 'tailor' such spectra, an original, accelerator-driven, neutron source and spectrum shaping assembly for hospital-based Gd-NCT are presented and preliminary results are reported.
Subject(s)
Brain Neoplasms/radiotherapy , Gadolinium/therapeutic use , Models, Biological , Neutron Capture Therapy/methods , Radiometry/methods , Radiotherapy Planning, Computer-Assisted/methods , Computer Simulation , Humans , Radiation Dosage , Radiotherapy DosageABSTRACT
The interest of manufacturing, governmental, and safety personnel in using paint schemes on propeller and rotor blades is based on improving the visual conspicuity of those blades when they are rotating. While propeller and rotor paint schemes may serve to reduce the number of fatalities and injuries due to contact with a rotating blade, there is little information about the circumstances surrounding such accidents. Brief reports provided by the National Transportation Safety Board of all "propeller-to-person" accidents from 1965-79 were examined and analyzed in terms of airport lighting conditions, actions of pilots, actions of passengers and groundcrew, phase of flight operations, weather conditions, and others. Analyses based on 319 accidents showed a marked drop in the frequency of "propeller-to-person" accidents from 1975 through 1978. Several types of educational efforts directed toward pilots and groundcrew, both prior to and during that 4-year period, were examined as possible factors contributing to the accident rate decline. Accident patterns provide a basis for assessing the probable efficacy of various recommendations, including propeller conspicuity, for further reducing "propeller-to-person" accidents.
