Dose measurements and calculations in the epithermal neutron beam at the Brookhaven Medical Research Reactor (BMRR)

The characteristics of the epithermal neutron beam at BMRR were measured, calculated, and reported. This beam has already been used for animal irradiations. We anticipate that it will be used for clinical trials. Thermal and epithermal neutron flux densities distributions, and dose rate distributions, as a function of depth were measured in a lucite dog-head phantom. Monte Carlo calculations were performed and compared with the measured values. 2 refs., 4 figs., 1 tab

Risk factors in spinal bone mineral densitometry

Absorptiometric methods have gained widespread use in quantification of bone mineral density, particularly for the assessment of fracture risk in osteoporosis. The aim of the present study was to determine the radiation burden to patients and operators related to the assessment of bone mineral status in the spine using either dual X ray absorptiometry (DXA), or single energy spectrum quantitative computed tomography (SE-QCT). Effective dose to adult patients from spinal bone mineral density measurement was found to be in the order of 1 μSv in DXA and 100 μSv in SE-QCT. The radiation burden to the operators was found to be low

Software upgrading in a CT scanner: Influence on quantitative CT

Purpose: In an attempt to improve field uniformity and CT number stability, the software in a CT scanner was replaced with a new version. The purpose of the present study was to investigate the influence of the software upgrading on density measurements. Material and Methods: The upgrading influence was investigated by means of a torso phantom (European spinal). The phantom simulates a torso which contains 3 vertebrae of different densities. Results: Despite the use of a reference standard under the phantom, the software change resulted in: a) improved short-term precision; b) increased density values at 80 and 100 kVp, decreased at 130 kVp; and c) increased influence of the kVp on the values. Conclusion: The results of the present study suggest that conversion factors have to be used in density values for reference populations as well as in the values of patients undergoing follow-up studies

Educational and training activities in personal dosimetry in Greece

An individual monitoring programme is one of the main components of any radiation protection programme since it constitutes the mean for assessing and thus optimising the doses of occupationally exposed workers. The Greek Atomic Energy Commission (GAEC) is the competent authority for radiation protection and nuclear safety in Greece. GAEC's educational and training activities in the field of occupational radiation protection at the national and regional (Eastern Europe) level are presented, along with the relevant activities of the University of Ioannina in the region of North-West Greece, as an example of a local education and training programme. The curricula of two postgraduate courses addressed to qualified experts and medical physics experts and mainly the modules dedicated to individual monitoring are discussed as well. © The Author 2010. Published by Oxford University Press. All rights reserved

Large Sample Neutron Activation Analysis: correction for neutron and gamma attenuation

A Large Sample Neutron Activation Analysis (LSNAA) facility is under development at the GRR-1 research reactor, NCSR "Demokritos". The LSNAA facility design incorporates sample irradiation in the reactor graphite thermal neutron column and subsequent measurement of the activity induced in a gamma spectroscopy system with gamma ray transmission measurement options included. The Monte Carlo neutron and photon transport code MCNP-4C was used to model the facility. Appropriate correction factors accounting for neutron field perturbation during sample irradiation and high-purity germanium detector efficiency for the volume source were derived. The results of the computations were experimentally verified by measurements for a set of known materials. The LSNAA facility will be used to perform multi-element, non-destructive, contamination-free analysis of large volume samples with high sensitivity and excellent sampling. End-users of the facility will be archaeological, environmental, bio-medical research laboratories and industry