A COMPUTER-CONTROLLED CONFORMAL RADIOTHERAPY SYSTEM .2. SEQUENCE PROCESSOR

Purpose: A sequence processor (SP) is described as part of a larger co mputer-controlled conformal radiotherapy system (CCRS). The SP provide s the means to accept and then translate highly sophisticated radiatio n therapy treatment plans into vendor specific instructions to control treatment delivery on a computer-controlled treatment machine. Method s and Materials: The sequence processor (SP) is a small workstation co mputer that interfaces to the control computer of computer-controlled treatment machines, and to other parts of the larger CCRS system. The system reported here has been interfaced to a computer-controlled race track microtron with two treatment gantries, and also to other linear accelerator treatment machines equipped with multileaf collimators. An extensive design process has been used in defining the role of the SP within the context of the larger CCRS project, Flexility and integrat ion with various components of the project including databases, treatm ent planning system, graphical simulator, were key factors in the deve lopment. In conjunction with the planned set of treatment fields, a pr ocedural scripting language is used to define the sequence of treatmen t events that are performed, including operator interactions, communic ations to other systems such as dosimetry and portal imaging devices, and database management. Results: A flexible system has been developed to allow investigation into procedural steps required for simulating and delivering complex radiation treatments. The system has been used to automate portions of the acceptance testing for the control system of the microtron, and is used for routine daily quality assurance test ing. The sequence processor system described here has been used to del iver all clinical treatments performed on the microtron system in 2 ye ars of clinical treatment (more than 200 patients treated to a variety of treatment sites). Conclusions: The sequence processor system has e nabled the delivery of complex treatments using computer-controlled tr eatment machines. The flexibility of the system allows integration wit h secondary devices and modification of procedural steps, making it po ssible to develop effective techniques for insuring safe and efficient computer-controlled conformal radiation therapy treatments.