Investigations of dose response of BANG polymer-gels to carbon ion irradiation.

In this presentation BANG polymer-gel dosimetry using magnetic resonance imaging (MRI) is applied to densely ionizing radiation such as carbon ion beams. BANG polymer-gels were irradiated with monoenergetic 12C ions at an energy of 205 MeVu(-1). The irradiation of the gels with doses up to 100 Gy were performed at the radiotherapy facility of the GSI, Darmstadt, Germany. For comparison with sparsely ionizing radiation data were obtained for 6 MV photon radiation, too. It was the object to examine the saturation effect for densely ionizing radiation that occurs at high values of linear energy transfer (LET). Up to now the dose response is unknown for mixed radiation fields of primary carbon ions. Therefore, to facilitate such conversions of measured MR signals into dose model calculations are proposed. This model relies only on heavy ion track structure and the experimentally determined photon response.