A therapy system and method treats an internal target of a patient (16). A treatment plan (36) is received to treat the internal target. The treatment plan (36) includes a plurality of treatment fractions including correspondences (38) between the internal target and an external body surface based on a pre-procedural planning image (14) and pre-procedural tracking data (20). Before selected treatment fractions of the plurality of treatment fractions, a pre-fraction planning image (50) of the target is received, tracking data (20, 52) of the external body surface of the patient (16) is received, and the correspondences (38) between the internal target and the external body surface are updated based on the received pre-fraction planning image (50) and the received tracking data (20, 52). Therapy is delivered to the patient (16) in accordance with the treatment plan (36) and using the updated correspondences (38).
