Proton intracranial radiosurgery (SRS) and fractionated stereotactic (FSRT) treatments have a long history, dating back to the 1960s. Proton SRS/FSRT treatments have predominantly focused on benign intracranial conditions such as meningioma, arteriovenous malformation (AVM), pituitary adenoma, and vestibular schwannoma. Dosimetric comparisons between proton and photon SRS delivery have revealed the superior normal tissue-sparing effect of protons, predominantly seen with large and irregularly shaped lesions, and most obvious in the low isodose regions. Clinical data demonstrate that proton SRS achieves control rates comparable to those achieved with photon techniques. These excellent outcomes are achieved with minimal acute and few late toxicities, but given the differences in treatment era, the proton series generally report slightly higher complication rates, compared to contemporary SRS results. More modern series have outcomes comparable to photon SRS results. These results therefore support the use of proton SRS/FSRT, especially in patients who will likely be long-term survivors and have larger tumors, and where the lower dose regions would include critical organs-at-risk (OARs).
