This is accomplished with the use of a stereotactic head frame. This is a device which is temporarily attached to the skull with small metal points. Imaging studies such as a planning CAT scan can be done with the frame in place. The frame provides unchanging points of reference so that any 3 dimensional point within the brain can be measured to accuracies of less than 1 millimeter. Planning CT with stereotactic head frame in place.
Frame provides fixed reference points for localizing tumor.
The CAT scan is then transferred to a treatment planning computer and a three dimensional model is created which contains the tumor and the important nearby structures which must be avoided. From this model, the appropriate angles for the incoming radiation beams are calculated to provide the maximum dose to the target while minimizing dose to the critical structures of the brain. Computer reconstruction of tumor volume within skull. The biological and clinical justification for fractionated dosing is discussed in the review following. Go to the Case History .