Dedicated Medical Ion Accelerator Design Study. Final Report.

摘要

Results and conclusions are reported from a design study for a dedicated medical accelerator. Basing efforts on the current consensus regarding medical requirements,the resulting demands on accelerator and beam delivery systems were analyzed,and existing accelerator technology was reviewed to evaluate the feasibility of meeting these demands. This general analysis was augmented and verified by preparing detailed preliminary designs for sources of therapeutic beams of neutrons,protons and heavy ions. The study indicates that circular accelerators are the most desirable and economical solutions for such sources. Synchrotrons are clearly superior for beams of helium and heavier ions,while synchrotrons and cyclotrons seem equally well suited for protons although they have different strengths and weaknesses. Advanced techniques of beam delivery are of utmost importance in fully utilizing the advantages of particle beams. Several issues are invloved here. First,multi-treatment room arrangements are essential for making optimal use of the high dose rate capabilities of ion accelerators. The design of corresponding beam switching systems,the principles of which are already developed for physics experimental areas,pose no problems. Second, isocentric beam delivery substantially enhances flexibility of dose delivery. After several designs for such devices were completed,it was concluded that high field magnets are necessary to keep size,bulk and cost acceptable. Third,and most important,is the generation of large,homogeneous radiation fields. This is presently accomplished with the aid of scattering foils,occluding rings,collimators,ridge filters,and boluses. A novel approach,three-dimensional beam scanning,was developed here,and the most demanding components of such a system (fast-scanning magnet and power supply) were built and tested. (ERA citation 03:029177)