Varian Medical Systems Inc. of Palo Alto, Calif., has received FDA 510(k) clearance for additions to its RPM respiratory gating system. The device optically tracks movement of a marker box on a patient’s chest that reflects tumor motion in the body. The addition allows the system to track movement of the patient and tumor in three dimensions, rather than just two. This information enables radiation therapists to move the patient if necessary and to adjust the treatment to avoid damage to normal tissue.