Intra-fraction motion gating during frameless Gamma Knife® Icon™ therapy: The relationship between cone beam CT assessed intracranial anatomy displacement and infrared-tracked nose marker displacement

摘要

MethodsGamma Knife Icon™’s high-definition motion management (HDMM) system gates treatment delivery should intra-fraction displacement of a nose marker exceed some user-defined threshold. A method, previously-validated with a phantom, is used to relate intra-fractional displacements of the nose marker to displacements of patient targets. Additionally, novel analysis is performed to ascertain the relationship between nose marker displacement and displacement of a 3D grid of coordinates throughout stereotactic space. This spatial information is used to retrospectively review HDMM threshold levels based upon real target locations.