The geometric properties of the small photon fields generated by a Co-60 irradiation device and a linear accelerator were investigated experimentally and with the aid of Monte Carlo calculations with respect to their suitability as reference radiation fields for dose measurements with the water calorimeter.

The response of a miniaturized dosemeter (developed in Italy) for clinical applications in the field of nanometry is at present being investigated at Department 6.6 with the aid of Monte Carlo simulation calculations. The first results show that the pulse height spectra calculated with conventional codes (MCNP and FLUKA) very strongly depend on the algorithms selected for the description of the...

For the calibration of the radioactive sources used for the therapy of prostate cancer - so-called seeds - PTB has developed a new primary standard measuring device which has been validated in the year under report on the basis of a comparison with calibrations of the National Institute of Standards and Technology (NIST). The deviations of the calibration values of NIST and PTB were smaller than...

The realization of the unit of the absorbed dose to water for interstitial brachytherapy, for example for the treatment of prostate carcinoma, has approached a little more. For low-energy photon radiation (up to approx. 40 keV) a new measurement method - based on an ionization chamber in a phantom - whose measurement volume can be varied has been developed.

At the accelerator facilities of PTB, nanometric spectra for monoenergetic He ions have for the first time been measured in the energy range between 0.1 MeV and 20 MeV and compared with Monte Carlo simulation calculations. Propane at a pressure of 1.2 mbar served as the measuring gas. For energies above approx. 0.4 MeV, the measured and calculated mean ionization cluster sizes are in good...

The measurand used in dosimetry for the therapy with X-radiation is the water absorbed dose.

For the simulation of radiation damages of the DNA, knowledge of all essential interaction processes between electrons and the components of the DNA is indispensable. As the interaction data so far known are still rather incomplete and in part even contradictory, the elastic differential electron cross sections of tetrahydrofuran (a main component of the DNA) were measured absolutely for primary...

For irradiations of extremity dosemeters, ISO recommends the use of a PMMA rod phantom 19 mm in diameter and 300 mm in length.

In many fields of physics, complete scattering cross section data are of great importance for the investigation of the electron transport in a medium. Examples are: transport phenomena in surface physics, plasma physics, dosimetry of ionizing radiation and atmospheric physics.

In Department 6.6, consistent cross section data for the elastic and inelastic scattering of electrons on argon have been...

For the first time, an international EUROMET measurement comparison was performed for beta radiation in the field of radiation protection. From Europe, the primary laboratories of Finland, France and Italy participated in addition to PTB which acted as pilot laboratory; from other continents, the institutes of Japan, Canada, Russia and the USA were involved. Most of the results agree within the...

A commercial, compact ESR spectrometer intended for use in industrial alanine dosimetry was investigated with respect to its possible use in radiation therapy dosimetry. If data analysis procedures developed at PTB are used, a relative measurement uncertainty of 1% (excluding the primary standard) at a dose of 10 Gy can be achieved. This indicates that such a spectrometer is indeed useable in...

The battery-operated data logger for simultaneous impulse counting, analogue signal measurement, serial data readout and data storage on one memory board is a new technical development.

The main component of the natural exposure of humans to ionizing radiation is the inhalation of ephemeral progenies of the radioactive rare gas "radon" which occurs in the earth's atmosphere in the form of the two nuclides Rn-222 and Rn-220. In epidemiological studies it is assumed that in the Federal Republic of Germany, approx. 5% of all lung cancer cases must be attributed to the inhalation of...

In a cooperation with different institutes, a measurement method and a detector system for the determination of the cross section of carbon combustion to oxygen are used, which allow the physical processes shortly before supernova explosions to be investigated.

For the generation of a reference atmosphere, ten Th-228 sources from which Rn-220 emanates were installed in the thoron progenies chamber. Each single source is located in a drawer in a lead cube. Opening and closing of the drawers with the sources inside is controlled from the outside via a source control system. If a source is immersed in the lead cube, this serves to shield the ionizing...

When measuring systems are calibrated in the thoron progenies chamber it must be ensured that the generated reference atmosphere is homogeneous with respect to the individual activity concentrations. However, a homogeneous distribution of Rn-220 is not that easy to ensure as this isotope has a half-life of only 55 s. This is why Rn-220 is supplied to the atmosphere via the source control system in...

Neutron spectrometry in plasma diagnosis requires complex data analysis procedures. A method which combines the procedures of the Bayes’s statistics and the maximum entropy allows parameters to be investigated which describe the plasma in fusion experiments.

A TDCR apparatus was constructed for determining activity with the aid of the liquid scintillation technique which supplements the existing method for determining activity and opens up new possibilities for calibration, also for nuclides with complex decay schemes.

At the heavy ion facility GSI in Darmstadt, Germany, a special form of radiotherapy is carried out which uses a high-energy carbon ion beam to destroy the tumour. The ion beam is thereby directed very precisely onto the whole tumour volume by means of the so-called raster-scanning method. To date, there exists no suitable primary standard for the determination of the absorbed dose to water for...

It was possible to determine with a standard measurement uncertainty of only 0.3% the relative response of the secondary standard measuring system based on the detection of radiation-induced free radicals in alanine for ultrahard photon radiation at 8 MV and 16 MV as used in radiotherapy. The measuring system is therefore applicable within the scope of examinations in therapeutically relevant...