Identification of treated target points for parkinsonism on gamma knife follow-up MR images.

Object: Identification of treated target points for Parkinsonism on follow-up MR images is difficult because of different orientations employed between the treatment and the follow-up MR scan. In the present work, the treated target points for Parkinsonism can be easily found, once the anterior-commissure (AC) and posterior-commissure (PC) have been defined in Leksell GammaPlan.

Methods: The follow-up MR images must first be defined with the Cartesian co-ordinate system using a non-fiducial based technique. The mathematics of 3-dimensional coordinate geometry is then applied to locate the treated target points for Parkinsonism. Spreadsheet computer software helped to calculate the exact coordinates of the treated target points quickly and accurately.

Conclusions: The coordinates of treated target points can be found easily based on the coordinates of the AC and PC points on the follow-up MR images. Different orientations employed between the treatment and the follow-up MR scan are no longer a problem.