Evaluating the Robustness of Intracranial Single-Isocentre Multiple Target Stereotactic Radiosurgery under Varying Treatment Planning Optimisation Methods

<p dir="ltr">Single Isocentre Multiple Targets (SIMT) Stereotactic Radiosurgery (SRS) is a relatively new radiotherapy technique for treating multiple lesions in a single treatment session. However, the accuracy and robustness of SIMT SRS treatment plans can be affected by various treatment planning and delivery errors. Implementing effective and robust treatment planning optimisations is crucial to minimise these errors and ensure that dose delivery remains accurate across all targets, especially in complex clinical scenarios. This study aims to evaluate the robustness of SIMT SRS treatment plans against a range of clinically relevant uncertainties by implementing different planning optimisations. Specifically, this study investigates how various optimisation strategies impact plan performance, focusing on the treatment plan’s ability to maintain a high target coverage while also minimising radiation dose to healthy tissues under different error scenarios. The set of original (OG) plans was first generated using standard planning protocols, then a set of three additional planning optimisations, including a monitor unit prioritisation (MU), aperture shape control (ASC), and a combination of the two (MU+ASC), were applied. The complexity metrics of these original plans were evaluated, and it was determined that the MU and MU+ASC optimisation methods reduced the complexity of the plans in comparison to the OG plans. A set of ten simulated errors was then introduced to the plans for each patient and optimisation methods. The robustness of each plan was investigated by evaluating the clinically relevant doses to organs at risk (OARs), PTV100%, GTV D98%, and the brain V12Gy dose.</p>