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Radiation monitoring strategy: factors to be considered.

In a nuclear or radiological emergency radiation measurements provide indispensable data needed in the management of the situation at hand. In order to assess the possible consequences correctly and to carry out proper countermeasures on time, the authorities must have a pre-prepared monitoring strategy at their disposal. There are, however, many different factors that affect a strategy. Thus, drawing up a comprehensive yet realistic emergency monitoring strategy is far from being an easy task. Some of the key factors related to strategies are reviewed and a simple way of producing a strategy plan is presented.

Decision Support Systems, Management↗

Radiation monitoring with reference to the medical environment.

This paper discusses the general principles of monitoring with some examples taken from the medical environment. The discussion is divided into two sections. The first section deals with the principles of personnel monitoring as well as the most common types of dosimeters used. Specific techniques applicable to the various areas of radiology are delineated. The second section deals with the use of portable monitors in a medical environment. The types of instruments commonly encountered and their limitations are detailed. This section also discusses the use of portable monitors as applied to the various areas of radiology. In each section some brief historical background has been added where possible.

Brachytherapy↗

[Conceptual bases of environmental radiation monitoring of an industrial city].

The mechanisms of radionuclide behavior in different environmental objects have been identified and studied. The radiation characteristics of controlled parameters have been shown to be in the range of mean long-term values that are characteristic for the technogenic background of a capital megapolis, they are not greater than those established by the monitoring standards and those required by regulating legislative documents. Areas have been regionalized by the radiation agent and set off as having high levels of natural radionuclides in the soil and high levels of radon in the soil air. It has been shown that, to ensure radiological monitoring under urban conditions, it is most reasonable to have an irregular network considering the concentration of radiation-risk enterprises, as well as urban architectural designs and division of areas by taking into account regional, geomorphological, and radiological factors. Basic trends in improving radioecological monitoring are given.

Environmental Exposure↗

Verification of methods of MIR-station's crew members personal dose estimation based on radiation monitoring data.

During the flight of the main missions on board the MIR station the individual doses of the crew members and the dose inside the core module was measured by the ID-3M package and R-16 dosimeter, respectively. Comparison of the skin dose measured by ID-3M unit and calculated by the transmission coefficient method on the basis of R-16 data in each of 23 main missions permits estimation of the systematic error of the transmission coefficient method. The mean value of this error is equal to 32%.

Astronauts↗

Evaluation of radiation monitor effectiveness for the detection of 85Kr.

As part of the preparations for the purging of TMI Unit-2, the 85Kr sensitivity of 12 radiation detector systems or system combinations was determined. Eleven of these were evaluated using a cube-shaped polyethylene-walled room containing a volume of 5.6 m3 (200 ft3). Krypton-85 gas was added to produce a concentration of 6.7 x 10(-6) muCi/ml in the test room. It was found that none of the ion chambers and scintillation detector systems were able to detect this concentration of 85Kr. Detectors employing thin window GM pancake probes were found to be sensitive enough to monitor this gas down to the unrestrictive area maximum permissible concentration level (MPC) of 3 x 10(-5) muCi/ml, while a large window gas flow proportional counter was found to be sensitive enough to monitor down to about 09.1 MPC. At the end of this experiment, 2.3 m3 (80 ft3) of the gas in the test room was pumped into a compressed air cylinder (scuba bottle) and was used to calibrate The Pennsylvania State University (PSU) Noble Gas Monitor. The sensitivity of this system, which employs gas compression and Ge(Li) spectroscopy, was demonstrated to be between 0.1 and 0.03 times MPC, depending on the counting time employed.

Air Pollutants, Radioactive↗

[Digital radiation monitoring system with a personal computer].

This paper describes a data processing system of monitors with a personal computer for a radioisotope laboratory. A monitoring system includes 6 area, 6 dust, and 3 gas monitors. Monitor signals through a multiplexer were fed to the personal computer which has analogue ports. Processed data were displayed on a color CRT, stored on a 5 inch mini floppy disk, and printed out as a report. We developed a data processing program with BASIC language. This system largely reduced manpower required to estimate radiation levels in the laboratory. The personal computer has sufficiently enough ability to construct a digital monitoring system for a small radioisotope laboratory.

Computers↗

[Chromosome abnormalities caused by computer video display monitors' radiation].

OBJECTIVE: Concerns were raised about the potential damaging effects of electromagnetic field (EMF) radiation emissions of ELF (extremely low frequency) and VLF (very low frequency) computer video display monitors (VDM), it was assessed the frequency of structural chromosome abnormalities and investigated the cell cycle kinetics in individuals occupationally exposed to VDM radiation. METHODS: Chromosome aberrations were investigated in 2,000 first cell cycle metaphases obtained after 48-hour cultures of peripheral blood lymphocytes drawn from 10 individuals occupationally exposed to VDM radiation (group E) and 10 controls (group C). Cell cycle kinetics was studied using the mitotic index (MI) and cellular proliferation index (CPI). RESULTS: Statistical analysis showed significantly higher frequencies of anomalous metaphases (E=5.9%; C=3.7%) and anomaly/cell (E=0.066+/-0.026; C= 0.040+/-0.026) in individuals exposed to VDM radiation. The most common cytogenetic alterations seen were chromatid breaks at frequencies of 0.034+/-0.016 in group E and 0.016+/-0.015 in group C. There was no significant difference between MI and CPI frequencies in both groups. CONCLUSIONS: The study findings suggest genotoxic effects of EMF emissions revealed by the higher frequency of chromatid breaks in individuals exposed to VDM radiation. However, there is a need of further studies on EMF genetic effects using other investigation methods.

Adult↗

Noninvasive diffuse optical measurement of blood flow and blood oxygenation for monitoring radiation therapy in patients with head and neck tumors: a pilot study.

This pilot study explores the potential of noninvasive diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS) for monitoring early relative blood flow (rBF), tissue oxygen saturation (StO(2)), and total hemoglobin concentration (THC) responses to chemo-radiation therapy in patients with head and neck tumors. rBF, StO(2), and THC in superficial neck tumor nodes of eight patients are measured before and during the chemo-radiation therapy period. The weekly rBF, StO(2), and THC kinetics exhibit different patterns for different individuals, including significant early blood flow changes during the first two weeks. Averaged blood flow increases (52.7+/-9.7)% in the first week and decreases (42.4+/-7.0)% in the second week. Averaged StO(2) increases from (62.9+/-3.4)% baseline value to (70.4+/-3.2)% at the end of the second week, and averaged THC exhibits a continuous decrease from pretreatment value of (80.7+/-7.0) [microM] to (73.3+/-8.3) [microM] at the end of the second week and to (63.0+/-8.1) [microM] at the end of the fourth week of therapy. These preliminary results suggest daily diffuse-optics-based therapy monitoring is feasible during the first two weeks and may have clinical promise.

Aged↗

[Determination of monitor radiation scattering contribution in photon radiation of clinical electron linear accelerators].

BACKGROUND: Modern linear accelerators permit the use of irregular fields due to their flexible collimator systems with separately movable jaws or multileaf collimators. When using such irregular fields in the clinical practice output factors have to be corrected for enhanced backscatter to the dose monitor as compared with the conventional block shieldings. METHODS: A method is presented to detect the monitor backscatter contributions to the output factor for irregular field settings. RESULTS: The monitor backscatter factors have been measured using a telescopic device for 2 different treatment head geometries (Varian Clinac 2100C/D, General Electric Saturne 15) and for 3 photon radiation qualities (nominal energies X6, X18, X12). A method is introduced to calculate the monitor backscatter for arbitrary irregular treatment fields from the experimental data for square or rectangular fields. CONCLUSIONS: Besides the corrections for changes in phantom scatter and changes in the aperture, corrections for monitor backscatter have to be taken into account in many clinical cases. They can contribute up to more than 10% compared with the monitor values for free regular fields.

Humans↗

Development and performance of the vehicle-mounted radiation monitoring equipment used in the Maralinga rehabilitation project.

The rehabilitation of the former nuclear test site at Maralinga involved (among other processes) the removal of contaminated soil from an area of approximately 2.5 km2. The two most stringent rehabilitation criteria required measurements to ensure that no radioactive particle exceeding 100 kBq of 241Am activity, and no area of 1 ha exceeding 3 kBq/m2 of 241Am activity, remained in the rehabilitated area. The project timetable required that the area be scanned at the rate of approximately 3 ha/day. Two vehicle-mounted detection systems were developed and constructed to obtain the necessary measurements in the available timeframe. The scientific basis for the designs are presented, together with details of the selected equipment and technical solutions found. The performance of this equipment in the field is discussed in terms of both its scientific and technical operation. Based on the experience gained at Maralinga, improved versions of this equipment were produced under contract for the People's Republic of China.

Americium↗