Management of multiple brain metastases via dual-isocenter VMAT stereotactic radiosurgery

Single-isocenter volumetric modulated arc therapy (VMAT) stereotactic radiosurgery (SRS) techniques to treat multiple brain metastases simultaneously can significantly improve treatment delivery efficiency, patient compliance, and clinic workflow. However, due large number of sharing the same MLC pair causing island blocking, there is higher low- intermediate-dose spillage normal dose organs-at-risk (OAR). To minimize this problem plan quality, study proposes a dual-isocenter planning strategy that groups lesions based on hemisphere location (left vs right sided) in parenchyma, providing less blocking reducing travel distance. This technique offers simplified while also increasing comfort compliance by allowing for be treated 2 groups. Seven complex patients with 5 16 (64 total) were planned single-isocenter VMAT-SRS using 10MV-FFF beam prescription 20 Gy each lesion. The isocenter was placed at approximate geometric center targets. Each replanned approach, generating plans placing combined targets side corresponding non-coplanar partial arcs. Compared VMAT, VMAT provided similar target coverage conformity spread intermediate reduction OAR. Reduction total monitor units time observed, but second setup verification, overall increased. Dual-isocenter approach provides superior options who may not tolerate longer traditional times as individual isocenters target. reduces amount spillage, further sparing OAR brain, potentially improving accuracy though localization left right-sided tumors set up.