Assurance of high quality linac-based stereotactic radiosurgery

Purpose: Stereotactic radiosurgery is generally a single, high-dose radiation treatment for the brain requiring targeting accuracy on the order of a millimeter. From the initial implementation of radiosurgery, therefore, quality assurance is an ongoing process of paramount importance. In this paper, we outline the basic elements of a quality assurance program for our linear accelerator that has been in use at Washington University Medical Center over the past 2 years. Methods and Materials: Various devices and procedures have been developed to verify the accuracy and safety of the stereotactic radiosurgery regimen. Specifically, we present methods for assessing the attainment of spatially correct patient images, the reliability of the computerized treatment planning system, achieving physical safety for the patient, as well as the proper operation of the radiation treatment device. Results: Our procedures have allowed us to assure quality patient treatments and, additionally, has permitted monitoring our performance for continual improvement. For example, a plot of targeting accuracy with the number of patients shows an asymptotic approach to a value within 0.6 mm of that ideally expected. Conclusion: To maintain high-quality patient care, one must review critical aspects of the treatment regimen on a periodic basis. Providing for the appropriate level of staff training, periodic reviews of procedures and maintenance of forms are also very important.