Clinical Evaluation of a Gamma Knife Inverse Planning System

Abstract

The clinical evaluation of an in-house developed gamma knife inverse planning system is presented. This system utilizes morphological characteristics (skeleton) of a target to search for optimal shots. The planning process is very efficient and accurate as it determines shot locations and shot sizes (i.e., collimator size and weight combination) simultaneously, taking into consideration the target size as well as its shape. In addition, the process guarantees an optimal spatial arrangement among shots so that excessive ‘hot spots’ are avoided and the global dose distribution conforms to the target shape. Patient cases with different target volumes and shapes were tested retrospectively using this inverse planning system. For the patient cases presented, the number of shots used ranges from 7 to 20, the planning time is in the range of 1–3 min (2-GHz Pentium 4 workstation). The dose conformity indices range from 1.36 to 1.62.