Impact of systematic MLC positional uncertainties on the quality of single-isocenter multi-target VMAT-SRS treatment plans.

Purpose: To study the impact of systematic MLC leaf positional uncertainties (stemming from mechanical inaccuracies or sub-optimal MLC modeling) on the quality of intracranial single-isocenter multi-target VMAT-SRS treatment plans. An estimation of appropriate tolerance levels is attempted.

Methods: Five patients, with three to four metastases and at least one target lying in close proximity to organs-at-risk (OARs) were included in this study.