Plenary Oral Presentations - Macquarie University Hospital

16 th International Meeting of the Leksell Gamma Knife ® SocietyMarch 2012, Sydney, AustraliaPH-102Clinical Implementation of the Gamma Knife Extend System:A Therapist’s Perspective2Amanda Schoenberger, 3 Robert Dryzmala, 3 Joseph Simpson, 2 Eric Filiput, 2 Christine Bossung,2Karen Watts, 2 Bridget Burke, 2 Barb Kienstra, 2 John Reed1Gamma Knife Center of Saint Louis2Barnes-Jewish Hospital3Washington University Medical SchoolThe Extend System, a non-invasive stereotactic Gamma Knife Perfexion accessory, permits fractionatedand sub-cranial treatments. The technique is useful when treating larger targets in previouslytreated regions or those close to adjacent risk zones. We report on our initial experience with tenpatients throughout bite-block fabrication, imaging, planning and treatment. We consider the impactof body habitus and location of the target on patient selection.Our initial experience with this technology has taught us valuable lessons for using the Extend System.We have developed procedural tips to aide in its success. Appropriate fabrication of positioning aidsand a comfortable patient are keys to reproducible patient set-up and treatment. Bite-block fabricationincludes a dental impression that is formed to the patient’s mouth. A plug is appropriatelydepressed into the impression material establishing the necessary opening for firm suction to the hardpallet. A vacuum pillow molds to the posterior head and neck. A mark placed at the top of the moldhelps to insert the patient’s head properly for each treatment. A measurement from the arch of thebite-block assembly to the patent’s anterior neck or chest records the height for future setting of thetreatment couch and CT couch during stereotactic imaging. Suction is then applied requiring propertechnique in order to maintain the suction level necessary for patient immobilization. Once the requiredsuction level is reached, the repositioning tool is used to record depth measurements on four sidesof the skull for the CT simulation process. These values provide guidance for duplication of set-up foreach subsequent treatment.Similar to treatment planning for the G-frame, a team of certified Gamma Knife users are required.The site, dose distribution and fractionation pattern are established by this team. Those patientsappropriate for the Extend System are usually given treatments of 3 to 5 fractions over the courseof 2 weeks.This innovative technology has proven successful for multiple patients at our institution in the hypofractionatedtreatment of gliobastoma multiforme, meningioma, leiomyosarcoma, skull base metastases,and brain stem lesions.56