Gamma Knife Radiosurgery With Mask Fixation Under General Anesthesia for Pediatric Patients.

Gamma knife radiosurgery (GKS) is performed on children by frame fixation of the skull under general anesthesia. With the introduction of the Gamma Knife Icon, treatment by fixing with a thermoplastic mask has become possible. In this study, we performed GKS by mask fixation under general anesthesia, measured the accuracy, and examined whether an accuracy equivalent to that of frame fixation could be guaranteed. We included three children who underwent mask fixation under general anesthesia between September and November 2020. After the induction of general anesthesia, a patient marker was attached to the nose, and the movement of the marker before mask fixation was measured using a real-time high-definition motion management (HDMM) system. The movement of the patient marker from the start to the end of treatment after mask fixation was monitored and measured. After the induction of general anesthesia, the movement of the patient marker was ≤0.3 mm in two cases and ≥1.0 mm in one case without mask fixation. When the mask was fixed, it was ≤0.2 mm in all three cases. It was confirmed that the marker could move even under general anesthesia without mask fixation, and it could be suppressed to a minimum after mask fixation. With the mask fixation method devised in this study, GKS under general anesthesia for children seems to be a safe and highly accurate method.