DETERMINING LOCATIONS OF INTRACEREBRAL LESIONS FOR PROTON RADIOTHERAPY

Using an external view of the head, the ability to direct a proton rad iotherapy beam at an intracerebral lesion is described, using a bioste reometric (BSM) technique. The positions of markers, recognizable on c omputed tomography (CT) or magnetic resonance (MR) images, at known lo cations on the skin of a patient's head are related to the site of the lesion seen on the images. The markers' positions are determined by a BSM device, incorporating six video cameras coupled to a computer. A transformation from a coordinate system, defined by the CT or MR image s, to another coordinate system, that of the Bsm device, allows the pr oton beam to be directed towards the lesion. Markers used in this work were solid steel spheres for CT and plastic spheres containing oil fo r MR images.