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

Background and Purpose: For 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 Methods: This 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. Results: IMPT-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<0.01), 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<0.01). IMPT was optimal for >= 69% of patients. Conclusions: IMPT-BH achieved the lowest MHD, MLD, and bilateral MBD compared to IMPT-FB, VMAT-BH, and VMAT-FB in the majority of patients.