Division of Radiation Physics Head: Dr. Fine Fiedler Staff

At present time more than half of all cancer patients are treated by radiotherapy, and it is assumed that the number will constantly rise in the future. One condition is the application of doses at a highest technical level to limit the radiation as precisely as possible to the tumour and thus to save surrounding tissue. Another one is the understanding of the interaction of ionising radiation with the cell, its organelles and their molecular structures. Thereby an important aspect to an increasing degree is the combination of radiation with substances that are able to modulate the radiation effect - to increase it in the tumour and to decrease it in healthy tissue. Especially the technologies of nuclear and radiation physics, in particular their methods of production and detection of ionising radiation, but also approaches of describing the interaction between radiation and matter are notably suitable to bring forward the development of radio therapeutic procedures. This is the aim the research projects of our division are based on.

Projects

Radiation Induced Cell Damage

In the project Radiation Induced Cell Damage the effect of ionising radiation is analysed in a subcellular level. For this the use of the ELBE electron beam for non conventional photon sources is of particular importance. In a first step a source of quasi-monochromatic photons with an energy range of 10 - 100 keV, based onelectron channeling in crystals, is established at ELBE. The research group is active in following fields:

• Radiobiology with soft X-rays
• Precision dosimetry in cellular structures
• Production of X-rays by electron channeling
• Radiation transport calculations.

Tomography and Tumour-Conform Radiotherapy

In the project Tomography and Tumour-Conform Radiotherapy the method of in-beam Positron Emmission Tomography (PET) was developed. It is a contribution to the German Heavy Ion Tumour Therapy Project (supported by Gesellschaft für Schwerionenforschung, Deutsches Krebsforschungszentrum, Radiologische Universitätsklinik Heidelberg as well as the HZDR). This project is operated at the experimental therapy facility at GSI Darmstadt and prepared for the application at the future clinical heavy ion therapy facility in Heidelberg. Special experience is available in the following fields:

• Technology of PET (detectors, signal- and data processing)
• Attenuation and scatter correction for PET
• Reconstruction methods for limited-angle tomography
• Radiation transport calculations for therapy with protons and ions

Photon Activation Therapy with quasi-monochromatic X-rays

In the project Photon Activation Therapy with quasi-monochromatic X-rays the increase of the effect of ionising radiation on cells and subcellular structures by combination with the effect of molecular targets is analysed. In a first step, by the use of quasi-monochromatic X-rays at ELBE, a contribution to the quantification of the influence on the biological effectiveness of photon radiation by the Auger effect on heavy metal atoms positioned close to the desoxyribonucleic acid of the cell nucleus is accomplished. The synthesis and evaluation of suitable metal-organic Rhenium-compounds takes place at the Institute of Bioanorganic and Radiopharmaceutic Chemistry of the HZDR. In addition to the fields already mentioned for the project Radiation Induced Cell Damage the development of algorithms for the description of the interaction of low energetic electrons with living matter has to be emphasized.