Medical imaging device for combined magnetic resonance imaging and irradiation and method for determining the configuration of shim units

A medical imaging system for combined magnetic resonance imaging and irradiation of an examination subject, the medical imaging system comprising:

• a magnetic resonance imaging device and a radiation generator that are mechanically linked to each other such that the radiation generator is structurally integrated with the magnetic resonance imaging device and the magnetic resonance imaging device and the radiation generator surround a patient bore for receiving and positioning the examination subject, wherein the magnetic resonance imaging device includes at least one main magnet operable to generate a magnetic field, and the radiation generator includes a radiation source operable to generate radiation, wherein one of the magnetic resonance imaging device and the radiation generator includes a static part and the other of the magnetic resonance imaging device and the radiation generator includes a rotatable part that is rotatable through an angle of rotation, wherein the rotatable part includes one or more main magnets of the at least one main magnet that are rotatable and are arranged so as to be rotatable around the static part, which includes the radiation generator, or the rotatable part includes the radiation generator and is arranged so as to be rotatable around the static part, which includes one or more main magnets of the at least one main magnet that are static;
• and
• at least two passive shim units, wherein at least one passive shim unit of the at least two passive shim units is a static shim unit that is stationary, and at least one passive shim unit of the at least two passive shim units is a rotatable shim unit that is fixedly connected to the rotatable part.