GANTRY STUDIES FOR THE PROPOSED HEAVY ION CANCER THERAPY FACILITY IN HEIDELBERG

The Heavy Ion Cancer Therapy Facility HICAT [1] proposed for the clinic in Heidelberg will contain three treatment rooms- one treatment room will be equipped with a fixed horizontal beam line and two treatment rooms will contain heavy ion gantries. In parallel to the design of the accelerator facility, the heavy ion gantries were subject of detailed studies at GSI during the last years. Different layouts of the gantry ion optical system and of the gantry structure have been compared. The mechanical stability during rotation was analyzed and the effects of deformations on the beam transport were studied. Finally, an integrated gantry concept was found which satisfies the requirements on beam position stability in the ISO center. The gantry quadrupole system must allow the generation of spot radii between 2 to 5 mm in the ISO-plane. This range of spot radii must be achievable at all rigidity levels and at all expected transverse emittance ratios up to ɛ x(y)/ɛ y(x) =1/5. Furthermore, the focusing properties should be independent from the gantry rotation angle (Fig. 1). 1