1. A radiosurgical method for treating a patient body having a target tissue, the target tissue associated with a disease state, the method comprising: acquiring planning image data from the target tissue; planning an ionizing radiation treatment of the target tissue using the planning image data so as to mitigate the disease; implanting a position surrogate within the body by advancing the position surrogate and an elongate flexible body through a blood vessel, releasably coupling the position surrogate to the target tissue so that the position surrogate exhibits movement of the target tissue, detaching the position surrogate from the flexible body and removing the flexible body from the patient body; and remodeling the target tissue by directing the planned radiation from outside the body toward the target tissue with reference to the implanted position surrogate thereby mitigating the disease.