NREC designed and implemented a medical image registration system to accurately estimate a patient’s position for therapy.

For radiotherapy and other forms of therapy to be successful, patients must be correctly positioned for treatment. The medical image registration system uses two-dimensional X-rays and three-dimensional CT scans to accurately estimate the position and orientation of a patient’s anatomy with respect to an external coordinate frame.

High-speed computer graphics algorithms render simulated X-rays from CT scan data in a fraction of a second. These high-resolution, simulated radiographs are compared with actual X-ray images using a novel image comparison algorithm. The comparison algorithm ignores noise in the images and clutter from the patient’s other anatomy to correctly estimate the patient’s position.

The system achieved sub-millimeter registration accuracies in preliminary tests, with total registration times on the order of 50 seconds. Tests using clinical patient data are underway.