SU-E-T-788: Validating the Use of Surfacing Mapping Tools for Motion and Irregular Breathing Pattern Monitoring On Lung SBRT Patients

Validating the Use of Surfacing Mapping Tools for Monitoring Motion and Irregular Breathing Patterns for Lung SBRT Patients Purpose: In this study, we have examined the utility of surface mapping in the treatment of lung SBRT patients. We examined the extent to which intra-fraction patient motion and irregular breathing patterns impact the accuracy of treatment deliveries. Materials and Methods: The C-RAD Catalyst, an optical surface mapping system was used to track the intra-fractional isocenter motion of five lung SBRT patients treated with VMAT. A respiratory tracking tool was used to track the breathing pattern of these patients and to correlate the breathing pattern to the isocenter motion. Results: For 2 of the 5 patients the isocenter displacement exceeding the 5mm planning margin for a portion of the treatment delivery with the time outside of tolerance at 2.2%, and 2.5%. Conclusions: 1) Breathing patterns may change between different fractions for the same patient; 2)Breathing patterns can change from the beginning to the end of the same fraction; 3) Not only amplitude, but also the baseline of breathing may change during an individual fraction; 4) We cannot predict which patients will have a stable isocenter in treatment even after the simulation study; and5)Real-time motion monitoring with surface-mapping tools and respiratory gating (free breathing or breath-hold) may provide clinically valuable solution in motion management for lung SBRT patients. The research is supported by funding from Elekta.