A therapy planning system for treating an internal target of a patient using a delivery control system configured to deliver therapy to the patient, said therapy system comprising: at least one processor (70, 72) programmed to: receive a treatment plan to treat the internal target, the treatment plan including a plurality of treatment fractions including correspondences between the internal target and an external body surface based on i) a pre-procedural planning image which is segmented to delineate the target and ii) pre-procedural tracking data; wherein the at least one processor (70, 72) is further programmed to perform the following steps before delivery of one or more selected treatment fractions of the plurality of treatment fractions: receive a pre-fraction planning image of the target; segment the target in the pre-fraction planning image by registering the pre-fraction planning image to the segmented pre-procedural planning image; receive tracking data (20, 52) of the external body surface of the patient; and update the correspondences between the internal target and the external body surface based on the received pre-fraction planning image wherein the target is segmented and the received tracking data (20, 52); and provide the treatment plan and the updated correspondences to the delivery control system in accordance with the treatment plan and using the updated correspondences. at least one processor (70, 72) programmed to: receive a treatment plan to treat the internal target, the treatment plan including a plurality of treatment fractions including correspondences between the internal target and an external body surface based on i) a pre-procedural planning image which is segmented to delineate the target and ii) pre-procedural tracking data; wherein the at least one processor (70, 72) is further programmed to perform the following steps before delivery of one or more selected treatment fractions of the plurality of treatment fractions: receive a pre-fraction planning image of the target; segment the target in the pre-fraction planning image by registering the pre-fraction planning image to the segmented pre-procedural planning image; receive tracking data (20, 52) of the external body surface of the patient; and update the correspondences between the internal target and the external body surface based on the received pre-fraction planning image wherein the target is segmented and the received tracking data (20, 52); and provide the treatment plan and the updated correspondences to the delivery control system in accordance with the treatment plan and using the updated correspondences. receive a treatment plan to treat the internal target, the treatment plan including a plurality of treatment fractions including correspondences between the internal target and an external body surface based on i) a pre-procedural planning image which is segmented to delineate the target and ii) pre-procedural tracking data; wherein the at least one processor (70, 72) is further programmed to perform the following steps before delivery of one or more selected treatment fractions of the plurality of treatment fractions: receive a pre-fraction planning image of the target; segment the target in the pre-fraction planning image by registering the pre-fraction planning image to the segmented pre-procedural planning image; receive tracking data (20, 52) of the external body surface of the patient; and update the correspondences between the internal target and the external body surface based on the received pre-fraction planning image wherein the target is segmented and the received tracking data (20, 52); and receive a pre-fraction planning image of the target; segment the target in the pre-fraction planning image by registering the pre-fraction planning image to the segmented pre-procedural planning image; receive tracking data (20, 52) of the external body surface of the patient; and update the correspondences between the internal target and the external body surface based on the received pre-fraction planning image wherein the target is segmented and the received tracking data (20, 52); and provide the treatment plan and the updated correspondences to the delivery control system in accordance with the treatment plan and using the updated correspondences.