Patent ID: 7953203

Claim:
A method of treating tissue at a target zone deep to a surface of a patient's body by emitting, from an x-ray source having a system axis defined in a global coordinate system, a collimated x-ray beam having a beam axis defined in the global coordinate system, said method comprising: (a) determining a reference axis defined relative to the patient's body, the reference axis having a known position and orientation in the global coordinate system; (b) determining a treatment axis that intersects the target zone, the treatment axis having a known position and orientation with respect to the reference axis and with respect to the system axis in the global coordinate system; (c) positioning the x-ray source to a first position with respect to the system axis, such that the beam axis intersects the treatment axis at (i) a first treatment site within the target zone and (ii) a first incident angle with respect to the treatment axis, and such that the beam axis intersects the surface of the patient's body at a first location; (d) emitting an x-ray beam toward the target zone along the beam axis, to irradiate the target zone with a first radiation dose; (e) rotating the x-ray source about the system axis to a second position with respect to the system axis, such that the beam axis intersects the treatment axis at (i) a second treatment site within the target zone and (ii) at a second incident angle with respect to the treatment axis, and such that the beam axis intersects the surface of the patient's body at a second location that is separated from the first location by a first distance; and (f) emitting an x-ray beam toward the target zone along the beam axis, to irradiate the target zone with a second radiation dose.