What's the chance of meningiomas for someone who's only had a few sessions of radiosurgery? does dna damage only occur if one's had lots of treatment?

Very low: If u r asking about the risk of developing menu goons as a result do the radiosurgery procedures, then it is very low assuming attention was paid at minimizing the 12gy low dose spill to normal meningeal tissues. Statistically it should be less than 1% long term.. Of course the risk of meningioma could be confounded by whatever it was that u were treated with srs for.

Depends: Radiosurgery is designed to minimize the radiation exposure beyond the target. While we cannot quantify the risk for developing meningioma, we do know the effect of radiation is dose dependent and not treatment number per se.

Very low: The chance of meningioma from brain radiation is about 5%, but it is delayed by about 20 years, and with the lower dose from radiosurgery, secondary meningiomas are very rare indeed. As medical director of a brain tumor clinic, having seen hundreds of radiosurgeries, I have yet to see a single secondary meningioma.