1. A radiation therapy planning and follow-up system comprising: a magnetic resonance (MR) scanner with a first bore which defines an MR imaging region which receives a subject along an MR longitudinal axis, the bore having a diameter of at least 70 cm; a second imaging scanner with a second bore which defines a second imaging region which receives the subject along a second longitudinal axis, the functional longitudinal axis being aligned with the MR longitudinal axis and the second bore having a diameter at least 70 cm; and a radiation therapy type couch which moves linearly through the MR and second imaging regions which positions the subject sequentially in the MR and second imaging regions.