Room: Exhibit Hall
Purpose: Develop a script in a commercial treatment planning system to automate the creation of uniformly-arranged spheres (grid-GTV) within a regular GTV to facilitate proton GRID therapy (Patent pending) auto-planning.
Methods: A spherical GTV target in a digital water phantom in RayStationÂ® (version 6.1) was used as a test case to fill the GTV target with a grid-GTV. The IronPython (version 2.7) script used built in RayStation functions. The function â€œBounding Boxâ€? was used to find the limits of the GTV target in the x, y, and z directions. â€œCreate ROIsâ€? was used to create spheres with pre-determined diameters (e.g. 3 mm) and spacing (e.g. 3 cm) within the GTV bounding limits. â€œROI algebraâ€? was used to union all the individual spheres into the grid-GTV structure. Delete ROI was used to delete all the individual spheres after the grid-GTV structure was created. Finally â€œROI algebraâ€? was performed to delete any grid-GTVs outside the target. The script allows for a user input of grid-GTV size and spacing through a graphic user interface (GUI). The user can also specify the degree of rotation along the superior-inferior and left-right axes, to minimize the overlap of the spheres in the beamâ€™s eye view. The auto-created grid-GTV is then used in spot placement and plan optimization during the process of inversely planning for pencil beam scanning proton GRID therapy.
Results: The script takes 1 minute on average to complete, while a manual creation of the same grid-GTV usually took more than 1 hour. The script can generate grid-GTV for any desired gantry angle.
Conclusion: This script can be applied to any target of any size in a water phantom or patient CT image, and greatly reduces the total time in the creation of proton GRID therapy plans in a proton treatment center.