The ion acceleration system or complex (T) for medical and / or other applications is composed in essence by an ion source (1), a pre-accelerator (3) and one or more linear accelerators or linacs (6, 8, 10, 13), at least one of which is mounted on a rotating mechanical gantry-like structure (17). The isocentrical gantry (17) is equipped with a beam delivery system, which can be either ‘active’ or ‘passive’, for medical and / or other applications. The ion source (1) and the pre-accelerator (3) can be either installed on the floor, which is connected with the gantry basement, or mounted, fully or partially, on the rotating mechanical structure (17). The output beam can vary in energy and intensity pulse-by-pulse by adjusting the radio-frequency field in the accelerating modules of the linac(s) and the beam parameters at the input of the linear accelerators.