Development of Imaging Techniques for Medical Accelerators in the QUASAR Group

Ions offer an increased precision in radiotherapy due to their specific depth-dose properties. This precision can only be fully exploited if exact knowledge of the particle beam properties, as well as the exact range of the particles in the inhomogeneous target, is available. The QUASAR Group has addressed the key issues in a number of different ways: Using a monolithic active pixel sensor, designed for dead time-free operation, a beam monitoring system capable of monitoring pulsed and continuous beams at typical therapeutic energies and intensities in real time during patient treatment has been developed; using a non-intrusive detector system based on the VELO detector, variations in beam properties without intersecting the beam core altogether will be developed; using liquid ionization chambers, the group aims at obtaining information on the biological quality of the beam; using a simple set-up based on a silicon pixel detector, developed for the ALICE experiment, the feasibility of detecting the distal edge of the Bragg peak in antiproton beams by detecting the pions resulting from pbar-nucleon annihilations has been demonstrated. This paper gives an overview of these studies.