In this paper, we propose a low cost, robust vision based system for
monitoring patient movements during stereotactic radiotherapy: the
Monocular Visual Patient Movement Monitoring (MVPM) System.
The system consists of a light weight mouth bite with dual fiducial
system used for position tracking. One set of fiducials consist of
easy-to-detect checkerboard whose 3D position can be tracked using
a pre-calibrated off-the-shelf camera and a set of radio-opaque rods
suitable for X-ray imaging. We describe the associated workflow
steps for using the system during planning and treatment phases.
Also we report experimental results for tracking accuracy using a
in-house phantom.