The present invention provides a radiation shield (204), in particular for shielding main coils (202) of a magnetic resonance imaging system (110), whereby the radiation shield (204) comprises a cavity (214) for housing at least one main coil (202), whereby the cavity (214) is formed between an inner cylindrical wall (206), an outer cylindrical wall (208), which are arranged essentially concentrically to each other, and two ring-shaped base walls (212), which interconnect the inner cylindrical wall (206) and the outer cylindrical wall (208), wherein at least one out of the inner cylindrical wall (206), the outer cylindrical wall (208), and the two ring-shaped base walls (212) is provided at least partially with an inner layer (216), which faces the cavity (214), and an outer layer (218), wherein the inner layer (216) is a layer comprising carbon fiber reinforced plastic, and the outer layer (218) comprises a metal, which is paramagnetic or diamagnetic. The present invention also provides a shielded main magnet (200) comprising at least one main coil (200) for generating a static main magnetic field in a magnetic resonance imaging system (110), and a radiation shield (204) as specified above, wherein the at least one main coil (202) is housed in a cavity (214) of the radiation shield (204).