Is gamma knife more risky than a surgical operation in a brain tumor?

Depends: Gamma knife is a type of very precise radiation that can deliver very high doses of radiation to small confined targets. It dose not require any surgery so in this sense it is safer than an operation. However, one must take great care when using this technique to ensure that the target is drawn correctly and that proper qa and oversight occur during the delivery of treatment.

Depends: Gamma knife only good for small tumors. Whether safe or not depends on location, open surgery can visualize and avoid critical structures such as cranial nerves. For deep seated lesions open surgery may have its limitations. Ask your neurosurgeon.