In interventional radiology, for an accurate determination of effective dose to the staff, measurements with two dosemeters have been recommended, one located above and one under the protective apron. Such 'double dosimetry' practices and the algorithms used for the determination of effective dose were reviewed in this study by circulating a questionnaire and by an extensive literature search. The results indicated that regulations for double dosimetry almost do not exist and there is no firm consensus on the most suitable calculation algorithms. The calculation of effective dose is mainly based on the single dosemeter measurements, in which either personal dose equivalent, directly, (dosemeter below the apron) or a fraction of personal dose equivalent (dosemeter above the apron) is taken as an assessment of effective dose. The most recent studies suggest that there might not be just one double dosimetry algorithm that would be optimum for all interventional radiology procedures. Further investigations in several critical configurations of interventional radiology procedures are needed to assess the suitability of the proposed algorithms.
Abstract:Very soon after the introduction of the application of thermoluminescene(TL)for dosimetric purposes the method was used also for environmental monitoring.Thermoluminescence dosimetry(TLD)systems are permanently developed and improved.The aim of the present paper is to help the reader to introduce TLD for environmental monitoring.Therefore the paper describes the brief theoretical background of thermoluminescence.The elements of TLD systems,such as detectors,readers and measurement cycle including annealing,package and storage,irradiation,readout and mathematical evaluation are summarised.The main characteristics of various TL systems(batch homogeneity,sensitivity,reproducibility,linearity,light sensitivity,fading and energy dependence)are analysed mostly from the viewpoint of use in environmental monitoring.Special attention is given to the performance test requirements of the International Electrotechnical Committee and the importance of intercomparisons.Some environmental dosimetry applications during the last ten years are also reviewed.
The alkaline comet assay was employed in the assessment of DNA damage in leukocytes of a worker incidently exposed to gamma radiation (221 mSv, 60Co source). The comet tail lengths and tail moments were studied. By using the alkaline comet assay immediately after accidental exposure a high level of DNA damage was recorded. The highest levels of DNA damage were recorded one day and one week after the radiation incident. Later on, a decrease in both comet parameters was observed. Although the level of DNA damage was diminished during a one year period, it was still elevated compared to normal values recorded in leukocytes of a healthy, unexposed person. The results obtained indicate that the alkaline comet assay is a rapid and sensitive microdosimetric technique and is suitable for in vivo human biomonitoring, especially in cases of incidental exposure to ionising radiation.
The aim of this work was to determine important dosimetric characteristics of several types of the most interesting tissue-equivalent thermoluminescent detectors (TLDs). Special attention was given to the determination of energy dependence for medium and low energy X rays. The following types of TLDs were investigated: (a) two new types based on lithium borate: Li2B4O7:Cu,In and Li,B4O7:Cu,In,Ag; (b) two types of the recently developed highly sensitive LiF:Mg,Cu,P material: TLD-700H and GR 200A and (c) two well known types of LiF:Mg,Ti detectors: TLD-100 and TLD-700. In order to determine their photon energy response characteristics, TLDs previously calibrated with 137Cs gamma rays were simultaneously irradiated with X ray beams in the range of effective energies between 33 and 116 keV. Measured energy responses (relative to air), normalised to those to 137Cs photons were compared with calculated data. Although the deviations of the measured data from the 'theoretical' predictions are different for all the investigated TLDs, there is no large difference in 'tissue-equivalency' between them.
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