Room: AAPM ePoster Library
Electron treatments often require custom blocks for each field. Blocks may be purchased from a fabricator, often used once and returned to the vendor or discarded. Designing a software tool to enable cataloguing and matching of existing electron cutouts encourages cost and time saving through reutilization.
The library was created in a Python environment. Existing blocks connected to original treatment plans were imported to the library via RTPLAN DICOM. Cutouts whose original plans could not be found had apertures traced, scanned, and digitized using image processing software. A desired cutout is compared against every image in the library by computing the minimum distance between every pair of coordinates and finding the closest match. The planner can then determine if the match is sufficient for treatment, otherwise the new cutout can be requested and its aperture added to the library. The matching software was validated by comparing cutouts of simple known geometry and dosimetrically using the gamma index. Ten cutouts were simulated for three field sizes and the dose plane were compared to the other nine cutouts using 1mm and 3% gamma criteria.
For geometric validation, the program outputs a minimum distance of 3cm as expected, confirming the algorithm’s functionality. For dosimetric validation, the program ranked the cutouts correctly within ±1 ranks.
This electron cutout library may cut costs and reduce time to treatment. Future work involves integrating the aperture comparison tool into the treatment planning software via API scripting. Once this interface is established we will be able to actively update our library, providing better results with time.