Heidelberg 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
ST: Strahlen- und Medizinphysik
ST 7: Strahlentherapie mit schnellen Ionen II
ST 7.9: Vortrag
Dienstag, 14. März 2006, 12:50–13:00, D
Experimental fragmentation studies with 12C therapy beams — •Emma Haettner, Hiroshi Iwase, and Dieter Schardt — Biophysik, GSI, Planckstr. 1, 64291 Darmstadt
For heavy ion therapy the effect of nuclear fragmentation is of particular importance as it affects the depth-dose profile and results in a complex radiation field. The primary particle beam is attenuated exponentially with increasing depth and the build-up of lighter fragments gives rise to a dose tail behind the Bragg peak.
Using 200 MeV/u and 400 MeV/u 12C beams delivered by the heavy ion synchrotron SIS-18 we investigated the fragmentation characteristics of these beams in a water absorber of variable thickness. The data include depth-dose profiles, attenuation of the primary ions and build-up of charged fragments as a function of depth. For the 12C beam attenuation measurements a telescope detector positioned close to the target exit provided energy loss and total energy information. It was found that approximately 70% of the 200 MeV/u and 30% of the 400 MeV/u primary 12C ions reached the Bragg peak. In addition, angular distributions for charged fragments were measured with the 400 MeV/u beam at various water depths. Particles were identified by coincident recording of time-of-flight and energy loss signals. The measurements were performed at angles from -1∘ to 10∘ in steps of 0.5∘ to 2∘. The amount of fragments spread forward in a cone with an opening angle of 20∘ was obtained by integration of the angular distributions.