The use of motion detector camera in uveal melanoma stereotactic radiotherapy

The standard stereotactic radiotherapy treatment for uveal melanoma uses several 6MV photon beams collimated through cones that focus the beam to the lesion. The patient head is immobilized using the head rest or a mask to minimize head motion during the treatment. Furthermore, the patient is also asked to stare at an object of regard (OOR) during treatment to focus the beams to the lesion and not irradiate normal parts in the orbit, e.g., the optic nerve. This setup usually encounters difficulties if the patient is weak and gets drowsy during the treatment or if the case involves a pediatric patient. The De La Salle University Medical Physics Department is developing a tool that will ensure accurate treatment during this procedure and to minimize dose to other normal tissues. A motion detector camera placed at the object of regard (OOR) is interfaced with a computer that sets a limit on the deviation of the eyeball from a preset position. Once the patient moves the eyeball beyond this limit, the program sends a signal to the linear accelerator to stop the treatment. A computer program will be developed to interface the detector camera to the linear accelerator. © International Federation for Medical and Biological Engineering 2007