EURADOS project on the impact of the proposed ICRU operational dose quantities.

Following the publication of the joint The International Commissions on Radiation Units and Measurements (ICRU) and on Radiological Protection (ICRP) report on new operational quantities for radiation protection, the European Dosimetry Group (EURADOS) have carried out an initial evaluation. The EURADOS report analyses the impact that the new quantities will have on: radiation protection practice; calibration and reference fields; European and national regulation; international standards and, especially, dosemeter and instrument design. The task group included experienced scientists drawn from across the various EURADOS working groups.

Uncertainties and characteristic limits of counting and spectrometric dosimetry systems.

In the event of a radiological emergency, early and reliable knowledge of radioactivity concentrations is important information for organising countermeasures to protect the general public and emergency workers. This is ensured by all European countries in operating airborne radioactivity and dose rate early warning networks. To increase the provided information, the development of new secondary standards based on scintillation detectors for the measurement of ambient dose rate equivalent was initiated in 2014. This paper shows the state-of-the-art of uncertainties and characteristic limits of low dose rate measurement that can be achieved by scintillation-based detector (CeBr3) and gas-based detectors (a high-pressure ionization chamber, HPIC). The comparison of the devices shows the performance and the metrological potential of the CeBr3 detector: Its uncertainty is already very close to the uncertainty of reference values. Looking at the question how to select a reference instrument, the CeBr3 detector with a special data evaluation is even superior to the HPIC and qualifies therefore as a modern secondary standard: Providing both, dose rate and nuclide information.

Novel spectrometers for environmental dose rate monitoring.

A new generation of dosemeters, based on the scintillators LaBr3, CeBr3 and SrI2, read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Müller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown.

INFLUENCE OF RADON PROGENY ON DOSE RATE MEASUREMENTS STUDIED AT PTB'S RADON REFERENCE CHAMBER.

The responses of electronic dose rate meters were investigated in a large volume radon chamber at PTB in a wide range of radon activity concentrations. The measurements were conducted under controlled laboratory conditions and measured dose rate data are compared with Monte-Carlo simulations. Consequences concerning environmental monitoring are described. A further result is that the direct measurement of the dose rates produced by radon progeny in air is hardly possible in radon atmospheres with high activity concentrations, because the major contribution of measured dose rates is produced by radon progeny on the housing of the dose rate instruments. The latter effect largely depends on the ability of surfaces to absorb radon progeny. The Monte-Carlo simulations revealed quantitative results on the height of the single contributions to the total dose rate measured in the radon chamber. When environmental dose rate measurements are performed, the plate-out on detectors can be neglected.

Measurement of thoron exhalation rates from building materials.

Thoron (220Rn) exhalation from building materials has become increasingly recognized as a potential source for radiation exposure in dwellings. However, contrary to radon (220Rn), limited information on thoron exposure is available. The purpose of this study is to develop a test method for the determination of the thoron exhalation rate from building materials. The method is validated, and subsequently the thoron exhalation rates from 10 widely-applied concretes, gypsums, brick, limestone, and mortar are determined. The measured thoron exhalation rates of these materials range from 0.01 Bq m-2 s-1 to 0.43 Bq m-2 s-1, with relative standard uncertainties between 6% to 14%.

Recent developments in radon metrology: new aspects in the calibration of radon, thoron and progeny devices.

Due to the importance of reliable measurements of radon activity concentration, one of the past developments in metrology was applied to the field of radon, thus meeting two basic needs: (1) the harmonisation of metrology within the scope of the mutual recognition arrangement, an arrangement drawn up by the International Committee of Weights and Measures for the mutual recognition of national standards and of calibrations issued by national metrology institutes and (2) the increased demands of the European Atomic Energy Community (EURATOM) directive, transferred into national radiation protection regulations with regard to natural radioactivity and its quality-assured measurements. This paper gives an overview of typical technical procedures in the radon-measuring technique group of PTB, covering all aspects of reference atmospheres (primary standards) for radon, thoron and their respective progenies.

The effect of various iodine supplementations and two different iodine sources on performance and iodine concentrations in different tissues of broilers.

1. The objective of this study was to determine the influence of iodine (I) supplementation of feed, within the range of the European guidelines, on the performance of broiler chickens and I transfer into different organs and tissues, especially meat. The main emphasis was to assess whether broiler meat could be enriched and used as an I source in human nutrition. 2. Two experiments were performed, one with KI and the other with Ca(IO(3))(2). For each experiment, 288 d-old broiler chicks were divided into 4 groups (72 birds/group) and fed on diets with supplementations between 0 and 5 mg I/kg feed. The birds were reared to 35 d of age under standard conditions. Six birds per group were slaughtered at 35 d and samples of blood, thyroid gland, liver, pectoral and thigh meat taken. 3. Iodine treatment did not significantly affect the growth and slaughter performance of the broiler chickens. In all investigated parameters, I concentrations increased significantly with increasing I intake of the animals. The lowest I concentrations were measured in the meat, but they were considerably higher in blood serum, liver and thyroid gland. Since the I content of meat was still low in the highest supplemented group (highest median concentration: 67·8 µg I/kg thigh meat), there is no evidence that this could substantially improve I supply in human nutrition.

Radon activity concentration--a Euromet and BIPM supplementary comparison.

For the first time, a comparison of radon activity concentration in air has been performed within the scope of Euromet. In the project 657, 'Comparison of calibration facilities for the radon activity concentration,' 12 participants from 9 countries compared different radon reference atmospheres at 1, 3 and 10 k Bq m-3 via a transfer standard. The comparison was listed as BIPM supplementary comparison EUROMET.RI(II)-S1. The results of most participants are correlated due to common traceability to one single radon gas standard producer. This makes a careful correlation analysis necessary to achieve an appropriate comparison reference value. The results of the comparison as well as the complex analysis of the correlated set of data is presented and discussed.

[Changes in blood flow characteristics as a cause of non-traumatic femur head necrosis]. / Veränderungen der Fliesseigenschaften des Blutes als Ursache der nichttraumatischen Hüftkopfnekrose.

Most authors associate avascular necrosis of the femoral head with ischemia, caused by injuries or diseases of the nutrient vessels or by alteration of the hemorheology. We examined the rheological properties of the blood in 39 patients with nontraumatic avascular necrosis of the femoral head by following tests: viscosimetry, filtrometry and aggregation of red blood cells. Aggregation of red blood cells showed statistically significant pathologic alterations. Our results confirm that irreversible agglutination phenomenons followed by ischemia can be caused by 1. stenosis or obliteration of nutrient vessels 2. rheologic alterations of the blood.