Beam selection for stereotactic ablative radiotherapy using Cyberknife with multileaf collimation.

•A fast optimisation framework is used to create IMRT SABR plans for Cyberknife.•The value of the Cyberknife multileaf collimator is investigated.•A beam selection algorithm is used to determine a subset of beam orientations.•Fifteen selected beams are sufficient to create high-quality treatment plans.•Treatment time is minimised using this approach.