Journal of Radiology
Open Access

Abstract

Noninvasive stereotactic radiosurgery with the Cyberknife system has been attempted for the treatment of ocular tumors by a number of institutions. However, due to the unpredictability of eye movement during treatment, 6D skull tracking cannot account for random ocular tumor positions and therefore compromise treatment delivery precision. A real-time tumor tracking system was proposed using a pupil-tracking technique. To test and demonstrate this new approach, we assembled a phantom system that includes a video camera, a spherical eye phantom, and a motion platform. The programmable motion platform is capable of producing eye motions comparable to clinical conditions. A simulated pupil on the eye phantom is tracked by the video camera. The key component in the new approach is the 2D/3D transformation that relates pupil?s projected 2D coordinate to tumor?s 3D location. The first step is to convert the tracked pupil?s 2D coordinate from its offset to the calibration center of the image plane to the rotation angles with respect to the 3D center of the eye. The second step is to establish a 3D transformation to determine the new tumor position. An interactive program was designed to demonstrate the process of the 2D/3D transformation. Error analysis was presented comparing the predicted and mechanically determined tumor positions. The simulation results shows that to achieve higher precision in radiosurgery for ocular tumors, real-time 3D tumor tracking through pupil tracking is feasible.

Biography

Hairong Chen is Doctoral student in the Department of Biomedical Engineering, University of Miami.