Define CyberKnife radiation therapy.

• A. CyberKnife is treatment given using a miniaturized photon linear accelerator.
• B. CyberKnife is treatment given using cobalt energy.
• C. CyberKnife is a type of specialized scalpel used during brain surgery.
• D. a and b

Answer: (D)

CyberKnife radiation therapy is a non-invasive, image-guided radiotherapy system that uses a robotic arm to deliver high-energy photon beams from a linear accelerator. The beams are shaped and directed from many angles so they converge on the tumor, allowing a high dose to the target while sparing surrounding healthy tissue. It does not rely on cobalt energy sources; that description would imply a cobalt-60 source, which CyberKnife does not use. It is also not a surgical instrument. So the accurate characterization is a system that uses a miniaturized photon linear accelerator to deliver photons from multiple directions for precise tumor targeting.