Systems and methods for treating a lung of a patient using guided radiation therapy or surgery

Systems and methods for treating a lung of a patient. One embodiment of a method comprises positioning a leadless marker in the lung of the patient relative to the target, and collecting position data of the marker. This method further comprises determining the location of the marker in an external reference frame outside of the patient based on the collected position data, and providing an objective output in the external reference frame that is responsive to movement of the marker. The objective output is provided at a frequency (i.e., periodicity) that results in a clinically acceptable tracking error. In addition, the objective output can also be provided at least substantially contemporaneously with collecting the position data used to determine the location of the marker.