Dosimetric audits of photon beams in radiation therapy centres in Rio de Janeiro, Brazil

Data related to 11 y of high-energy photon radiotherapy beam dosimetry are presented and analysed. Dosimetric evaluations were carried out using water phantoms and thimble ionisation chambers and are part of the radiation protection regulatory licensing process for medicine facilities of Brazilian government. Measurements were done at reference conditions for a standard absorbed dose of 100 cGy [cGy (=1 rad)]. The absolute per cent deviation between the measured and presumed delivered doses should not exceed the tolerance level of +/-3%. The first dosimetry survey from 1996 to 1998 showed a situation that was an object of concern. Deviations of 22 and 18.7% could be measured, although small deviations were also obtained. After 1998, the improvement in dosimetry quality control by the radiotherapy centres became clear, with most of the deviations situated within the +/-3% range. The decrease in the measured deviations presents the effective success of the Institute of Radiation Protection and Dosimetry audit programme for the improvement in the control of radiotherapy photon beams in Rio de Janeiro. Also, it is possible to recommend to Brazilian regulatory organisation a decrease in the tolerance level for dosimetric deviations in order to achieve a more precise dose delivered to patients in radiotherapy centres.     

Dredging and disposal of fine sediments in the state of Rio de Janeiro, Brazil.

Dredging is employed quite frequently in the state of Rio de Janeiro, especially for the installation and upkeep of commercial ports and rehabilitation of the hydraulic section of silted bodies of water. Until recently, all dredged material with no economic use was destined for marine disposal or stored at the edge of the water body. Since the 1990s, however, a new approach has been adopted for dredging as a result of pressure from the environmental organisations, encouraging closer interaction in Rio de Janeiro between the local and state public authorities and the universities on issues relating to licensing of this kind of activity. The recent experiments of the Civil and Ocean Engineering Programs of COPPE-UFRJ (Federal University of Rio de Janeiro) described herein are included in this context. The state of Rio de Janeiro has three bays, several coastal lagoon systems and a number of small and medium sized rivers in or close to urban areas, with a gentle slope as they near the sea. This is, then, a region highly susceptible to silting processes of water bodies, and therefore, to maintenance and/or environmental rehabilitation. As discussed in the article, fine and almost always organic sediments prevail, which is a considerable obstacle to the end disposal and possibility of reuse.     

Cost-benefit analysis of sustainable drainage systems considering ecosystems services benefits: case study of canal do mangue watershed in Rio de Janeiro city,Brazil

Clean Technologies and Environmental Policy - The increasing demands of humankind contribute to the scarcity of natural resources and foster climate changes. For this reason, sustainable...     

Spatial distribution of polycyclic aromatic hydrocarbons in Terminalia catappa L. (Combretaceae) bark from a selected heavy road traffic area of Rio de Janeiro City, Brazil

The levels of 21 polycyclic aromatic hydrocarbons (PAHs) with molecular weights between 128 Da (naphthalene) and 300 Da (coronene) were determined in Terminalia catappa L. (Combretaceae) bark. Tree bark samples were collected in the campus of Oswaldo Cruz Foundation, a green area located in a very intensive traffic area of Rio de Janeiro City, Brazil and about 10 km away from the city center. Samples were submitted to ultrasonic extraction with dichloromethane and analyzed by high-resolution gas chromatography-mass spectrometry. Individual PAH levels varied from 1.23 to 327 ng/g and phenanthrene, fluoranthene and pyrene predominated in all samples. Total PAH levels ranged from 242 to 1640 ng/g with a mean of 628 ng/g. The levels of total PAHs and of total carcinogenic PAHs showed not a clear dependence with tree location and distances to the main routes of that area. No correlation was observed also with PAH levels previously found in total suspended particulate thus indicating that in this area tree bark PAH levels cannot be used to assess their atmospheric levels.     

Interim storage of spent and disused sealed sources: optimisation of external dose distribution in waste grids using the MCNPX code

Radioactive sealed sources are in use worldwide in different fields of application. When no further use is foreseen for these sources, they become spent or disused sealed sources and are subject to a specific waste management scheme. Portugal does have a Radioactive Waste Interim Storage Facility where spent or disused sealed sources are conditioned in a cement matrix inside concrete drums and following the geometrical disposition of a grid. The gamma dose values around each grid depend on the drum's enclosed activity and radionuclides considered, as well as on the drums distribution in the various layers of the grid. This work proposes a method based on the Monte Carlo simulation using the MCNPX code to estimate the best drum arrangement through the optimisation of dose distribution in a grid. Measured dose rate values at 1 m distance from the surface of the chosen optimised grid were used to validate the corresponding computational grid model.     

Scholarly communication in transition: The use of question marks in the titles of scientific articles in medicine, life sciences and physics 1966–2005

The titles of scientific articles have a special significance. We examined nearly 20 million scientific articles and recorded the development of articles with a question mark at the end of their titles over the last 40 years. Our study was confined to the disciplines of physics, life sciences and medicine, where we found a significant increase from 50% to more than 200% in the number of articles with question-mark titles. We looked at the principle functions and structure of the titles of scientific papers, and we assume that marketing aspects are one of the decisive factors behind the growing usage of question-mark titles in scientific articles.