What is the difference between IMRT, VMAT, CyberKnife and Gamma Knife radiotherapy?

All are external-beam radiation therapy: a machine outside the body sends high-energy beams toward the cancer. IMRT (intensity-modulated radiation therapy) is a 3-dimensional method that uses computer-generated images of the tumor's size and shape and aims thin beams of differing intensities from many angles, reducing damage to nearby healthy tissue. Stereotactic radiosurgery uses special equipment to position the patient and precisely give a single large dose, used mainly for brain tumors and disorders. Gamma Knife therapy, per NCI, is a type of stereotactic radiosurgery that tightly focuses gamma rays on small lesions in the head or neck. Stereotactic body radiation therapy applies similar precision to tumors elsewhere in the body, dividing the total dose over several days. NCI's Dictionary does not list VMAT or CyberKnife as separate terms. This is general information, not medical advice.

Last updated: 2026-07-12

← Back to all questions