  A dedicated clinical synchrotron facility for cancer therapy using energetic
proton and ion beams (C, He and O) has been designed at GSI for the
Radiologische Universitaetsklinik at Heidelberg, Germany. The design of the
injector linac is presented. Suitable ion sources are discussed and results of
ion source test measurements are reported. The LEBT allows for switching
between two ion sources. A short RFQ accelerates the ions from 8 keV/u to 400
keV/u. It is followed by a very compact beam matching section and a 3.8 m long
IH-type drift tube linac for the acceleration to 7 MeV/u. Both rf structures
are designed for a resonance frequency of 216.816 MHz and for ion
mass-to-charge ratios up to A/q = 3 (12C4+, (H_3)+, 3He+, 16O6+).
