Towards the clinical implementation of intensity-modulated proton therapy for thoracic indications with moderate motion: Robust optimised plan evaluation by means of patient and machine specific information

Highlights: • Thoracic indications achieved clinically acceptable VMAT and IMPT treatment plans. • The superior dosimetric sparing of IMPT relative to VMAT was demonstrated. • Comprehensive 4D robustness evaluation of IMPT optimisation was conducted. • For this study, plan robustness with 3D robust optimisation was sufficient. • Accurate patient positioning and recurrent volumetric imaging remained essential. Compared to volumetric modulated arc therapy (VMAT), clinical benefits are anticipated when treating thoracic tumours with intensity-modulated proton therapy (IMPT). However, the current concern of plan robustness as a result of motion hampers its wide clinical implementation. To define an optimal protocol to treat lung and oesophageal cancers, we present a comprehensive evaluation of IMPT planning strategies, based on patient 4DCTs and machine log files.