1. A radiation therapy machine comprising: at least one radiation delivery system controllable to direct a radiation beam preferentially to a located tumor region of a patient during a radiation treatment session; an imaging system operable to image a region of interest holding a tumor at multiple times during the radiation treatment session; an electronic computer executing a computer program fixed in a non-transient medium to: (a) receive electronic data representing tissue of a region of interest of the patient from the imaging system, the electronic data providing data values associated with spatial positions; (b) segregate the data according to data values and spatial positions into multiple regions; (c) identify at least one region as a tumor according to a predetermined tumor characteristic; and (d) output a location of the region identified as a tumor to the radiation delivery system to change the radiation beam according to that location.