Spreading of a heavy ion beam with the dual-ring double scattering method

A flat radiation field for heavy ion beams is used in research experiments and clinical treatments. When a flat field is required, a beam spreading system must be installed for a beam line; thus a simple and affordable method is desirable. To achieve the carbon ion beam spreading, we employed a dual-ring double scattering method (DDSM), which consists of an initial scattering foil and a dual-ring subsequent scatterer. The scatterers for the DDSM were designed and tested to verify the flatness of the radiation field of the carbon ion beam. We obtained 100 mm of the flat radiation field in the isocenter plane for the 2D radiation field, as expected. For the 3D radiation field, we obtained a field size of 80 mm. With a 60-min setup time, using the DDSM system, and by placing only two scatterers, we can form the flat radiation field.