A radiation therapy planning and follow-up system (10) includes an MR scanner (12) with a first bore (16) which defines an MR imaging region (18) and a functional scanner (26), e.g., a nuclear imaging scanner, or a CT scanner with a second bore (30) which defines a nuclear or CT imaging region (36). The first and second bores (16,30) have a diameter of at least 70 cm, and preferably 80-85 cm. A radiation therapy type couch (90) moves linearly through the MR imaging region (18) along an MR longitudinal axis and the nuclear or CT imaging region (36) along a nuclear or CT longitudinal axis which is aligned with the MR longitudinal axis. The couch positions a subject sequentially in the MR and nuclear or CT imaging regions (18, 36). A fusion processor combines an image representation generated from data collection in the MR imaging region (18) and an image representation generated from data collection in the nuclear or CT imaging region (36) into a composite image representation and a planning processor (112) generates a radiation therapy treatment plan according to the composite image.
