Improved organs-of-interest dose reduction potential with intensity modulated proton therapy and breath-hold in mediastinal lymphoma

Background and PurposeFor mediastinal lymphoma patients, comparative data on intensity modulated proton therapy in breath-hold (IMPT-BH) versus other radiation techniques remain limited, particularly regarding dose-volume histogram (DVH) metrics and normal tissue complication probability (NTCP) for late side effects. Materials and MethodsThis retrospective in silico planning study included 58 lymphoma patients, treated between 2019 and May 2024, having 4D-CT and BH-CT available.Four plans per patient were made: volumetric arc therapy in free-breathing (VMAT-FB), VMAT-BH, IMPT-FB, and IMPT-BH.An absolute dose difference 1 Gy was considered clinically relevant, and patients were assigned to the optimal technique. ResultsIMPT-BH resulted in the lowest average mean heart dose (MHD) at 5.4 Gy (p<0.01)compared to VMAT-FB (8.0 Gy), VMAT-BH (6.3 Gy) and IMPT-FB (5.8 Gy).IMPT-BH resulted in the lowest average mean lung dose (MLD) at 6.7 Gy (p<0.05),compared to VMAT-FB (9.2 Gy), VMAT-BH (7.5 Gy), and IMPT-FB (7.3 Gy).Average bilateral mean breast dose (MBD) was lower with IMPT (2.1 Gy) compared to VMAT (3.2 Gy; p<0.05).IMPT was optimal for 69% of patients. ConclusionsIMPT-BH achieved the lowest MHD, MLD, and bilateral MBD compared to IMPT-FB, VMAT-BH, and VMAT-FB in the majority of patients.