Room: Exhibit Hall
Purpose: Dynamic conformal arc (DCA) therapy offers a simple and efficient solution in many treatment planning scenarios. Arc therapy naturally produces highly focused isdose distributions ideal for stereotactic body radiation therapy (SBRT). However, most initial DCA plans are not suitable for treatment without additional manual and time consuming leaf pattern modification. In this work we introduce an automated tool for aperture optimization of DCA (oDCA) treatment beams to improve conformality.
Methods: Twenty patients were randomly selected patients for analysis. A DCA plan was created and fitted to the planning target volume. A second plan was refitted to an new optimized structure which was generated using a Matlab routine and the initial plan's isodose cloud. The new structure was fitted using the same DCA functionality. The coverage for all plans was held at 99% target volume to 100% of prescription dose. Conformity index (CI), ratio of 50% RX to target volume (R50), and maximum dose were calculated and recorded for both DCA plans.
Results: On average the oDCA plans improved CI (13.19%), R50 (4.90%) and maximum dose (2.76%) as compared to DCA plans. The percentage of plans meeting RTOG 0813 CI criteria of 1.2 improved from only 20% to 100%.
Conclusion: DCA treatment provides a simple treatment solution with many strengths including quick and efficient delivery, no additional patient specific quality assurance, highly accurate dose calculation due to relatively large apertures, and fewer patient setup and motion concerns. Aperture optimized DCA plans maintain low complexity with a high level of dose conformality making oDCA a ideal treatment planning technique for stereotactic treatments.