Biomedical subjects

R A Surette

Publications and source records attributed to R A Surette.

5 recordsLinked to original sources

PubMed2005

Evaluation of two personal dosemeters in polyenergetic mono- and multi-directional neutron fields.

The neutron dose-equivalent response of two commercially available electronic personal neutron dosemeters was studied in several laboratory-produced broad-spectrum neutron fields. Fluence-weighted mean energies ranged from 200 keV to 4 MeV; personal dose-equivalent rates ranged from 75 to 10 mSv h(-1); and angles of incidence were multidirectional, 0 degrees, 30 degrees and 60 degrees. Three of these fields have been shown previously to resemble ones found in CANDU (Canadian Deuterium Uranium is a registered trademark of the Atomic Energy of Canada Limited) power plant workplaces. Both dosemeters were found to perform reasonably well across the range of energy spectra and angles of incidence. One type of dosemeter displayed values of the personal dose equivalent that were, at worst, within a factor of approximately 2 of the reference values and, at best, within a few per cent of the reference values. The other type displayed values of the personal dose equivalent that were consistently within unity and 20% of the reference values. Although the radiological performance of one was found to be more accurate, this device was also found to be the less rugged of the two. Some of the data acquired in this work were compared with results previously published by others. There was consistency between these sets of data.

Humans↗

PubMed2002

Classical microdosimetry in radiation protection dosimetry and monitoring.

Classical microdosimetry concerns the measurement and analysis of the spectrum of radiation energy deposition events in simulated microscopic tissue-equivalent sites. Over the past three decades, classical microdosimetry has been extensively applied for the direct measurement of dosimetric quantities, such as the ambient dose equivalent, and for the spectroscopic properties of tissue-equivalent proportional counters that have led to methods of mixed-field analysis and particle identification. This paper reviews some of the special applications of classical microdosimetry such as the determination of kerma coefficients, differential dosimetry and aviation dosimetry. Also reviewed are some of the technological innovations related to the application of microdosimetry in operational health physics and in particular the development of multi-element proportional counters and detectors based on gas microstrip technology.

Dose-Response Relationship, Radiation↗

PubMed1998

14CO2-in-air sampling with passive diffusion samplers.

Passive diffusion samplers designed for measuring HTO-in-air have been evaluated for measuring 14CO2-in-air. Controlled exposures to HTO-in-air, 14CO2-in-air, and a combination of the two gases were carried out. The sampling rate of the 14CO2-in-air was found to be approximately 0.7 that of HTO-in-air. This value is consistent with the calculated relative sampling rates based on the diffusion coefficients of the gases. Passive diffusion samplers currently used for sampling HTO-in-air at CANDU facilities have been shown to be suitable for also measuring 14CO2-in-air and HTO-in-air simultaneously when prepared with the appropriate sampling solution.

Air Pollutants, Radioactive↗

PubMed1993

Evaluation of electret ion chamber for tritium measurement.

Commercial E-PERM radon-in-air monitors modified to detect tritium in air have been evaluated. Each monitor consists of a small ion chamber with access holes around the sides to allow the air to diffuse into the chamber, and an electret at the bottom to establish an electrostatic potential. Radioactive gas inside the volume generates ions, which are collected by the electret. The reduction of charge (and subsequent reduction in surface potential) on the electret is a measure of the integrated exposure. Two types of detectors, a 50 cm3 model and a 200 cm3 model, were tested for tritium-in-air concentrations from 1 to 60 MBq m-3, and gamma-absorbed dose rates from background levels to 50 microGy h-1. The HTO-in-air response of the modified E-PERM monitors was 3.3 +/- 0.3 V MBq-1 m3 h-1 for the 200 cm3 and 0.8 +/- 0.2 V MBq-1 m3 h-1 for the 50 cm3 monitor. For external gamma radiation (226Ra), the 200 cm3 chamber gave a response of 7.6 +/- 1.8 V microGy-1 and the 20 cm3 chamber 1.8 +/- 0.5 V microGy-1. The detection limit was about 3.6 and 15.2 MBq m-3 h for the 200 and 50 cm3 chambers, respectively. The accuracy and limit of detection of the electret detectors are limited by the accuracy in measuring the surface potential on the electret.

Air Pollutants, Radioactive↗

PubMed1993

Tritium sampling and measurement.

Current methods for sampling and measuring tritium are described. Although the basic techniques have not changed significantly over the last 10 y, there have been several notable improvements in tritium measurement instrumentation. The design and quality of commercial ion-chamber-based and gas-flow-proportional-counter-based tritium monitors for tritium-in-air have improved, an indirect result of fusion-related research in the 1980s. For tritium-in-water analysis, commercial low-level liquid scintillation spectrometers capable of detecting tritium-in-water concentrations as low as 0.65 Bq L-1 for counting times of 500 min are available. The most sensitive method for tritium-in-water analysis is still 3He mass spectrometry. Concentrations as low as 0.35 mBq L-1 can be detected with current equipment. Passive tritium-oxide-in-air samplers are now being used for workplace monitoring and even in some environmental sampling applications. The reliability, convenience, and low cost of passive tritium-oxide-in-air samplers make them attractive options for many monitoring applications. Airflow proportional counters currently under development look promising for measuring tritium-in-air in the presence of high gamma and/or noble gas backgrounds. However, these detectors are currently limited by their poor performance in humidities over 30%.

Environmental Pollutants↗