Whole-brain radiotherapy with hippocampus sparing and simultaneous integrated boost to metastases: A plan quality comparison study between Ethos, HyperArc, VMAT and Tomotherapy.

This study provides a concise and structured overview of a dosimetric comparison study conducted to assess the feasibility and effectiveness of 4 advanced radiotherapy techniques in treating brain metastases with hippocampus sparing and simultaneous integrated boost (HS-WBRT+SIB). Eleven patients with brain metastases previously treated with radiotherapy were included in the study. Planning CT scans with 2 mm slice thickness and MR imaging were used for contouring and dose prescription. The bilateral hippocampus and other organs at risk (OARs) were automatically contoured, and hippocampal avoidance regions (HAR) were defined as a 7 mm 3D expansion around the hippocampus. Gross tumor volume for each metastasis (GTV met) and planning target volume for metastases (PTV met) were delineated. The whole-brain CTV (CTV WB) and planning target volume for whole brain (PTV WB) were defined accordingly. Treatment planning and optimization were conducted using state-of-the-art radiotherapy techniques: Ethos, HyperArc, VMAT, and Tomotherapy. Tomotherapy achieved the highest D98% for PTV met , indicating the best metastasis coverage. HyperArc plans showed the highest D98% for PTV WB , suggesting superior whole-brain coverage. Tomotherapy demonstrated significantly lower D98%, D2%, and D mean values for the hippocampus, indicating its superiority in sparing the hippocampus. VMAT resulted in the lowest D2% values for the eyes, optic nerves, brainstem, and hypophysis, showing the best sparing of these critical structures. Tomotherapy consistently achieved lower D mean values for parotids, oral cavity, and lips compared to the other techniques. The dosimetric comparison revealed distinct strengths and weaknesses for each radiotherapy technique. Tomotherapy excelled in sparing the hippocampus, while VMAT showed promise in sparing OARs. HyperArc plans demonstrated the best overall whole-brain coverage. These findings should guide clinicians in selecting the most suitable technique based on patient characteristics and institutional resources. [ABSTRACT FROM AUTHOR]