Robotic Radiosurgery with Beams of Adaptable Shapes

In radiosurgery, a moving beam of radiation acts as an ablative surgical instrument. Conventional systems for radiosurgery use a cylindrical radiation beam of fixed cross-section. The radiation source can only be moved along simple standardized paths. A new radiosurgical system based on a six degree-of-freedom robotic arm has been developed to overcome limitations of conventional systems. We address the following question: Can dose distributions generated by robotic radiosurgery be improved by using non-cylindrical radiation beams of adaptable cross-section? Geometric methods for planning the shape of the beam in addition to planning beam motion are developed. Design criteria considered in this context are: treatment time, radiation penumbra as well as transparency of interactive treatment planning. An experimental evaluation compares distributions generated with our new radiosurgical system using cylindrical beams to distributions generated with beams of adaptable shapes.