OPTIMIZATION OF DOSE DISTRIBUTION FOR LINEAR ACCELERATOR-BASED STEREOTAXIC RADIOSURGERY

The work presented in the paper addresses a method for obtaining the o ptimal dose distribution for LINAC-based stereotactic radiosurgery. As many targets have nonspherical or irregular shapes and three-dimensio nal dose calculations included in dose optimisation, long computation times are required to determine the optimum isocentre separation and c ollimator sizes to shape the irregular target using the multiple-isoce ntre approach, by trial-and-error types of method The simple approach, using a computer-aided design optimisation technique and a fast appro ximate dose model, has been developed to find the optimum isocentre po sitions and collimator sizes quickly and automatically. A spherical do se model has been developed to represent the dose for a standard arc s ystem with a single isocentre. The implementation of computer-aided de sign algorithms with the spherical dose model and their application to several cases are discussed. It is shown that the spherical dose mode l gives dose distribution similar to that of the exact dose model, whi ch makes this simple dose model more efficient, with computer-aided de sign optimisation, in finding optimum isocentre positions and collimat or sizes used in stereotactic radiosurgery.