What it is
Stereotactic radiosurgery (SRS) — delivered by Gamma Knife, CyberKnife, or a dedicated linear accelerator — concentrates multiple beams of radiation on a precise target from many different angles simultaneously. Each individual beam carries a small dose; the high dose is deposited only where the beams converge. The surrounding tissue receives a fraction of the total dose, which is what allows SRS to treat targets adjacent to sensitive structures.
Despite the name, it involves no incision. The procedure is typically completed in a single outpatient session, though some platforms deliver treatment over a few fractions.
What SRS can and cannot do
SRS controls tumor growth or obliterates the target — it does not remove tissue. For acoustic neuromas and meningiomas, the goal is growth arrest (and the tumor may remain visible on imaging for years, even when successfully treated). For brain metastases, SRS achieves local control in 85–90% of treated lesions. For arteriovenous malformations, the AVM undergoes gradual obliteration over 2–3 years after treatment.
SRS is not appropriate for large tumors that need volume reduction, tumors causing significant mass effect that requires urgent relief, or lesions where tissue diagnosis has not been established.
Coordination with neurosurgery
The decision between surgery and radiosurgery — or a combination — is made based on diagnosis, tumor size, location, patient health, and goals. In many cases, both options are reasonable and the choice depends on what matters most to the patient: avoiding surgery versus speed of effect. These tradeoffs are best discussed when both surgical and radiation oncology perspectives are available.
At North County Neurosurgery, patients who are candidates for SRS are referred to local radiation oncology colleagues with whom we coordinate care closely.