Dresden 2000 – wissenschaftliches Programm
ST 4.5: Vortrag
Dienstag, 21. März 2000, 17:30–17:45, PHY C213
Dosimetry with ionization chambers in 12C ions radiotherapy — •C. Brusasco, B. Voss, D. Schardt, M. Krämer, and G. Kraft — Gesellschaft für Schwerionenforschung, Planckstr.1 , 64291 Darmstadt
At the therapy facility of GSI, 12C beams are employed in the treatment of cancer and the irradiation is precisely conformed to the target volume by means of an active beam-delivery system. The treatment plans are characterized by great complexity and high instantaneous dose rates and it is therefore important to verify the correct release of the irradiation with 3D dose measurements and good granularity.
In the therapy with 12 C ions, the dose deposited in the target volume results from the interaction of primary ions with different energies as well as of secondary fragments. Therefore, solid state detectors as thermoluminescence detectors and photographic emulsions cannot be employed in particle therapy, because of quenching effects depending on the energy and kind of charged particle interacting. In contrast, ionization chambers do not suffer from saturation effects but, in the commercially available solutions, do not offer a high spatial resolution either.
The principles of dose measurements with ionization chambers and the investigations performed at GSI on their performances with 12C ions irradiation are presented, as well as a new technical solution that separates the spatial information from the dose measurement for the dosimetry with the active beam-delivery system of GSI.