Purpose: 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. Previously, we designed a software tool to catalog and match existing electron cutouts to desired cutouts to encourage cost and time saving through reutilization. The current objective is to test the feasibility and functionality of the tool in a clinical environment by surveying three dosimetrists.
Methods: A library of 140 electron plans were created from all-electron treatments between 10/01/2019-10/01/2020. A sample of 10 electron plans not included in the library was chosen. Electron blocks from the sample were exported and compared using the software. The software’s closest 3 matches were imported back into the treatment plan for each patient. Each dosimetrist had the flexibility to adjust the SSD, collimator angle, and isocenter to get the best coverage and conformity. The dosimetrists were asked to rank the coverage, conformity, and most suitable plan (if any).
Results: In both the conformality and coverage tests, the dosimetrists agreed that a library-selected block conformed and gave adequate coverage for 7 out of 10 of the chosen patients. The average rank of the chosen block assigned by the dosimetrists agreed with the algorithm. The D90 for each cutout was compared against the clinical cutout, with the accepted cutouts per plan varying by less than 3.7% The D90 varied more than 3.7% from clinical for the 3 rejected cutouts.
Conclusion: All dosimetrists agreed that the tool was easy to use. On average the dosimetrists agreed that the system works well in a clinical environment and that it would significantly increase the speed of treating patients. Future work includes translation into an API script and growth of the electron cutout library.