Single-Fraction Stereotactic Radiosurgery for Intracranial Targets

The field of SRS has developed rapidly in the past decade. A few proton centers, more than 200 LGUs, and countless numbers of modified linacs are now delivering stereotactic treatments to intracranial targets. Treatment planning and treatment delivery capabilities have developed to the point where conformal dose distributions can be planned and delivered to irregular targets with any of these modalities in a few hours. Precision methods of holding the patient for the planning studies and for the treatments have reduced the risks associated with these single-fraction high-dose treatments. The physical properties of proton beam radiation provide a novel platform for delivering high-dose radiation to a limited target volume while minimizing the irradiation of adjacent normal tissues. The advantage of such a platform is especially evident in radiosurgical treatment of large-volume or irregularly shaped tumors. Technical aspects of proton radiosurgery have matured to a level of sophistication equal to, if not exceeding, that of gamma knife or linac radiosurgery. As with photon radiosurgery, an effective proton radiosurgery program requires a dedicated team of radiation oncologists, neurosurgeons, and medical physicists with a detailed understanding of the physics, radiobiology, and clinical efficacy of proton beams.