Development of treatment planning for scanning irradiation at HIMAC

In order to utilize an intensity-controlled raster scan method at the new treatment facility in HIMAC, we have developed, as a first step, a research version of a treatment planning tool. In this tool, treatment plans are produced according to the following steps: (a) import a planned target volume (PTV) delineated on a CT data set, (b) determine the primary treatment parameters, (c) convert the PTV in the CT system to the one in the water equivalent system, (d) choose beam positions within the PTV, (e) optimize the scan trajectory, (f) determine the particle numbers for each pencil beam and (g) produce the beam steering file. As an example, a treatment plan was produced for the data of a patient treated at HIMAC in this paper. The reliability of the tool was confirmed with irradiation experiments according to the obtained beam steering file.