Program Information
First Experiences and Perspectives in Using Direct Multicriteria Optimization (MCO) On Volumetric-Modulated Arc Therapy (VMAT) for Head and Neck Cancer
Samantha Edgington*, Christopher Cotter, Paul Busse, Bruce Crawford, and Yi Wang, Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
Presentations
MO-FG-CAMPUS-TeP2-2 (Monday, August 1, 2016) 5:00 PM - 5:30 PM Room: ePoster Theater
Purpose: To report the first experiences and perspectives in using direct multicriteria optimization (MCO) on volumetric-modulated arc therapy (VMAT) for head and neck (H&N) cancer.
Methods: Ten prior patients with tumors in representative H&N regions were selected to evaluate direct MCO-VMAT in RayStation v5.0 beta. The patients were previously treated by intensity-modulated radiation therapy (IMRT) with MCO on an Elekta linear accelerator with Agility multileaf collimator. To avoid radiating eyes and shoulders, MCO-VMAT required one to three partial-arc groups, with each group consisting of single or dual arcs. All MCO-VMAT plans were approved by a radiation oncologist. The MCO-VMAT and MCO-IMRT plans were compared using V₁₀₀, D₅, homogeneity index (HI) and conformity index (CI) for planning target volume (PTV), Dmean and D₅₀ for six parallel organs, and Dmax for five serial organs. Patient-specific quality assurance (QA) was performed using ArcCHECK for MCO-VMAT and Matrixx for MCO-IMRT, with results analyzed using gamma criteria of 3%/3mm.
Results: MCO-VMAT provided better V₁₀₀ (+0.8%), lower D₅ (-0.3 Gy), lower HI (-0.27) and comparable CI (+0.05). MCO-VMAT decreased Dmean and D₅₀ for multiple parallel organs in seven of the ten patients. On average, the reduction ranged from 2.1 (larynx) to 7.6 Gy (esophagus). For the nasal cavity and nasopharynx plans, significant reduction in Dmax was observed for optics (up to 11 Gy), brainstem (6.4 Gy), cord (2.1 Gy) and mandible (6.7 Gy). All MCO-VMAT and -IMRT plans passed clinical QA. MCO-VMAT required slightly longer planning time due to the more complex VMAT optimization. The net beam-on time for the MCO-VMAT plans ranged from 80 to 242 seconds, up to 9 minutes shorter than MCO-IMRT.
Conclusion: With similar target coverage, reduced organ dose, comparable planning time, and significantly faster treatment, MCO-VMAT is very likely to become the modality of choice in RayStation v5.0 for H&N cancer.
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