The dosemeters used to measure beta radiation have been subjected to an annual quality control by the PTB for six years now. Since then, all dosimeter models used in Germany have passed these controls.
In Germany, for persons who are occupationally exposed to radiation, monitoring with personal dose equivalent meters is legally prescribed. Besides the whole-body dosimeters which are to be worn on the trunk, also passive extremity dosimeters are used which are often worn around the fingers. Extremity dosimeters are used for beta radiation measurements, especially in medicine. All dosimeters of this type are released and assessed by dosimetry services. PTB is thereby responsible for quality control. Quality control takes place in two stages:
In the first stage, the designs are submitted to a thorough check with regard to their properties before the dosimeter is released for use. In the case of beta dosimeters, this control is carried out according to a directive.
In the second stage, the routine operation is checked yearly at the dosimetry services via so-called "periodic comparison measurements". The dosimeters are thereby exposed by PTB to a well known dose - which we we will call HPTB in the following. Then, the dosimetry services analyse the dosimeters and determine their measured value, HDST, of course without knowing the value of HPTB. As a measure of quality, the quotient HDST/HPTB is used which is 1.0 for an ideal dosimeter. The figure shows the values of these quotients in relation with the dose for all comparison measurements which have been carried out with beta radiation up to now. The lines plotted indicate the admissible limits for this quotient. Due to the requirements of radiation protection, these limits narrow towards high doses.
The condition for passing the yearly comparison measurements is that 90% of all quotients for each design of a service lie within these limits. If this requirement is not met by one dosimeter design for the comparison measurement, a repetition is carried out for this dosimeter. This has never been the case up to now. In summary, one can say that this type of two-stage quality control is particularly efficient.Contact:
Erika Schow | alfa
A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University
A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences