%0 Journal Article %T Robustness Evaluation of a Novel Proton Beam Geometry for Head and Neck Patients Treated with Pencil Beam Scanning Therapy %A Sheng Huang %A Haoyang Liu %A Jiajian Shen %A Huifang Zhai %A Maura Kirk %A Brett Hartl %A Alexander Lin %A James McDonough %A Stefan Both %A Haibo Lin %J International Journal of Medical Physics,Clinical Engineering and Radiation Oncology %P 308-322 %@ 2168-5444 %D 2018 %I Scientific Research Publishing %R 10.4236/ijmpcero.2018.73025 %X Background: To evaluate the robustness of head and neck treatment using proton pencil beam scanning (PBS) technique with respect to range uncertainty (RU) and setup errors (SE), and to establish a robust PBS planning strategy for future treatment. Methods and Materials: Ten consecutive patients were planned with a novel proton field geometry (combination of two posterior oblique fields and one anterior field with gradient dose match) using single-field uniform dose (SFUD) planning technique and the proton plans were dosimetrically compared to two coplanar arc VMAT plans. Robustness of the plans, with respect to range uncertainties (RU = ¡À 3% for proton) and setup errors (SE = 2.25 mm for proton and VMAT), in terms of deviations to target coverage (CTV D98%) and OAR doses (max/mean), were evaluated and compared for each patient under worst case scenarios. Results: Dosimetrically, PBS plans provided better sparing to larynx (p = 0.005), oral cavity (p < 0.001) and contralateral parotid (p = 0.004) when compared to VMAT. CTV D98% variations were higher from SE than from RU for proton plans (-1.1% ¡À 1.3 % vs -0.4% ¡À 0.7% for nodal CTV and -