Heidelberg 2006 – wissenschaftliches Programm
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ST: Strahlen- und Medizinphysik
ST 7: Strahlentherapie mit schnellen Ionen II
ST 7.8: Vortrag
Dienstag, 14. März 2006, 12:40–12:50, D
Experimental and theoretical study of the neutron dose produced by carbon therapy beams — •Hiroshi Iwase, Emma Haettner, Dieter Schardt, Michael Kraemer, and Gerhard Kraft — Biophysik, GSI, Planckstr. 1, 64291 Darmstadt
High-energy 12C ions offer favorable conditions for the treatment of deep-seated local tumor. Several facilities for the heavy ion therapy are planned or under construction, for example the new clinical ion-therapy unit HIT at the Radiological University Clinics in Heidelberg.
For the purpose to provide further reliable models for the treatment planning, it is essential to evaluate the secondary fragment production and to include these contributions to the therapy dose with higher accuracy than those of the existing treatment planning systems.
Secondary neutrons are most abundantly produced in the reactions between 12C beams and tissues. The dose contribution to tissues by a neutron is fairly small compared to ones of the projectile and the other charged fragments due to no ionization and small reaction cross-sections, however it distributes in a considerably wider region beyond the bragg-peak because of the strong penetrability.
Systematic data on energy spectra and doses of secondary neutrons produced by 12C beams using water targets of different thicknesses for various detection angles have therefore been measured in this study at GSI Darmstadt. The measured data are compared with theoretical predictions by the heavy ion Monte-Carlo code PHITS. The use of the measured and calculated data is discussed for improving databases of secondary fragments for treatment planning.