Fast range compensation inside the beam line for beam tracking in particle therapy.

Fast range adaptation is essential for three dimensional (3D) beam tracking for precise irradiations of moving targets with scanned ion beams. Electromagnetically controlled ion beam deflection in combination with a fixed absorber inside an ion beam delivery system has been considered as a fast range adaptation method for moving targets. As a feasibility test of this method, ion beams were deflected with magnets on a static wedge degrader at a thickness corresponding to the required range adaptation. Beam profiles at target position were investigated both in experiments and simulations. The measured horizontal and vertical beam profiles of 5-11 mm FWHM for specified range shifts of up to ±15 mm water equivalence were found to be in good agreement with simulations. [ABSTRACT FROM AUTHOR]