Norwegian Consensus Guidelines for Selection of Neuro-Oncology Patients to Proton Therapy

anatomy, continuous cardiac and respiratory motion, and the need to spare critical structures such as the mitral valve and left ventricle.This report presents a case of left atrial UPS treated with adjuvant proton therapy (PT), focusing on technical challenges, motion management strategies, and clinical outcomes.Methods: A 75-year-old woman presented with heart failure and dyspnea.Imaging revealed a 6-cm left atrial mass obstructing mitral inflow (Figure 1).On May 31, 2024, she underwent tumor excision with tricuspid annuloplasty.Following an R1 resection with positive surgical margins, adjuvant PT was delivered to the tumor bed with a total dose of 60 Gy in 30 fractions over six weeks (September 4 to October 15, 2024).In the absence of a dedicated cardiac 4D-CT simulation system, simulation was performed using 4D-CT.Treatment incorporated image-guided radiation therapy (IGRT) and respiratory motion control with an abdominal compression belt.A repainting technique was implemented to mitigate intrafractional cardiac motion, effectively averaging dose delivery and minimizing interplay effects.Posterior and posterior oblique beam angles were selected to optimize dose conformity and reduce exposure to the ventricles and adjacent critical structures(Figure 2). Results:The patient completed the PT course without significant acute toxicities.Post-treatment imaging at 6 months demonstrated no evidence of local recurrence or distant metastasis.Follow-up echocardiography demonstrated stable left atrial and ventricular function, with mild mitral regurgitation and small tricuspid regurgitation consistent with postoperative changes.Clinically, dyspnea improved markedly, although intermittent atrial fibrillation persisted under medical management.Conclusions: This case demonstrates the feasibility and effectiveness of adjuvant proton therapy for left atrial UPS despite significant cardiac motion.The integration of repainting strategies, respiratory motion management, and strategic beam angle selection enabled precise target coverage while sparing critical cardiac structures, supporting the potential role of PT in the management of complex cardiac malignancies.