Research Presentations: Automatic IMRT and VMAT Treatment Planning for Head and Neck Cancer Zhilei Liu Shen 1 , Eric Murray 1 , Naichang Yu 1 , Matthew D. Kolar 1 , John F. Greskovich Jr 1 , Shlomo Koyfman 1 , Karl Bzdusek 2 , and Ping Xia 1 ; 1 Cleveland Clinic, Cleveland, OH, 2 Philips Healthcare Inc., Fitchburg, WI Purpose: Advanced radiotherapy treatment planning such as IMRT and VMAT is time-consuming and planner- dependent. Automatic planning tools have the potential to reduce planning time and to improve plan quality and consistency. This study compares automatically generated IMRT and VMAT plans with the clinical plans for head and neck cancer. Methods: Seventeen HN patients treated with step-and-shoot IMRT were selected. The treatment goal was to simultaneously deliver 70 Gy to ≥95% of the high dose PTV and 56 Gy to ≥ 95% of the low dose PTV. In a commercial treatment planning system, the first ten HN cases were used to create and fine-tune automatic planning techniques. Using these auto-planning techniques, nine-field step-and-shoot IMRT plans (AP_IMRT) and two-arc VMAT plans (AP_VMAT) were automatically generated for the other seven HN patients. The clinical and automatic plans were compared using dosimetric endpoints, homogeneity index (HI), and conformity index (CI). Paired t-tests were performed and the results were considered significant if the p-values were ≤ 0.05. Results: The population averaged dosimetric endpoints, HI, and CI were summarized. All auto-planning IMRT and VMAT plans met the clinical dose limit requirements. The coverage of low dose PTV was significantly improved by use of the auto-plans. The doses to normal tissues, such as brainstem, right paratid, larynx, trachea, and esophagus, were significantly reduced in the auto-plans. Compared with the clinical plans, the AP_IMRT plans had similar HI and CI, and the AP_VMAT plans had comparable HI and improved CI. Conclusion: Auto-plans generated using both IMRT and VMAT techniques can be directly accepted for patient treatments. This commercially available auto-planning tool can improve plan quality and consistency while increasing planning efficiency.