Abstract

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Title:: Evaluation of Auto-planning technique-based volumetric modulated arc therapy plan for early nasopharyngeal carcinoma

Author(s):: ZHANG Quanbin; PENG Yingying; YU Hui; ZHANG Shuxu; Radiotherapy Center, Cancer Center of Guangzhou Medical University, Guangzhou 510095, China

Keywords:: Keywords: nasopharyngeal carcinoma; Auto-planning; volumetric modulated arc therapy; dosimetry

Abstract:: Abstract: Objective To compare the dosimetric differences and planning qualities between conventional volumetric modulated arc therapy (mVMAT) plan and Auto-planning technique-based VMAT plan (aVMAT) for early nasopharyngeal carcinoma (NPC). Methods The clinical data of 20 patients with early NPC were analyzed retrospectively. Two kinds of VMAT plans, namely mVMAT plan and aVMAT plan, were designed for each patient. mVMAT plans were manually generated by experienced physicists, and aVMAT plans were automatically generated by Auto-Planning module in Pinnacle3 system. The dose distributions, organs-at-risk sparing, monitor units and planning time were evaluated and compared. Results The dose coverage and conformity index of the target areas in two groups met the prescription requirements. The homogeneity indexes of PGTV and PTV2 in aVMAT group were significantly better than those in mVMAT group, but there was no significant difference in conformity index between two groups. aVMAT plan was advantages over mVMAT plan in protecting spine cord and reducing the dose to the brain stem. Compared with those in mVMAT group, the average monitor units in aVMAT group was reduced by 6.83%, and the average planning time was reduced by 14.50%. Conclusion Compared with mVMAT plan, aVMAT plan for early NPC has better target dose distribution and reduces the dose to normal tissues. Additionally, aVMAT plan has higher optimization efficiency and plan execution efficiency.