Use of a micro-ionization chamber and an anthropomorphic head phantom in a quality assurance program for stereotactic radiosurgery.

Quality assurance methods used in association with radiosurgery must include all aspects of the radiosurgery process: visualization and localization of the target, treatment and dose planning and dose delivery. Presented here is a quality assurance method that utilizes an anthromorphic head phantom and a micro-ionization chamber to demonstrate precise target localization and accurate dose delivery. This micro-ionization chamber method offers an immediate readout which is both accurate and reproducible. Additionally, this method allows unlimited repetition of the dose measurement process without repeated radiographic localization studies as is necessary with the conventional methods of TLD, film, and Fricke gels. The method and techniques presented can be used in the acceptance testing and routine quality assurance of both linac-based and Gamma Knife radiosurgery units.