88 Integration of virtual simulation techniques into a live planning environment

Abstract

Virtual simulation offers many advantages over conventional simulation. The ability to produce Digitally Reconstructed Radiographs with contoured or digitally enhanced structures can considerably improve visualisation of the beam path. At the Norfolk and Norwich Hospital, however, great emphasis has for many years been placed on imaging of radiotherapy treatment set-ups using image intensifier based simulation. The department has achieved a virtually film free environment, with dedicated software for archiving static and moving images sequences to support this practice. As a result of this approach, in some ways, static virtual simulation was seen as a potentially retrograde step. Other disadvantages were seen as the inability to confirm beam alignment prior to treatment. This paper presents a method for integration of virtual simulation into a live simulation environment. Images are transferred from a nondedicated CT scanner to a Picker virtual simulation system located between two conventional radiotherapy simulators. The ACQSIM terminal is used for contouring and processing of CT data prior to its transfer to a networked Cadplan treatment planning system. Treatment plans are prepared and plan information is then passed back to the virtual simulator. Digitally reconstructed radiographs are viewed alongside fluoroscopy images of the patient to verify correct beam positioning. Moving image sequences showing breathing or other unavoidable motions of the patient are recorded on newly developed, PC based software. $25