Towards Knowledge Based Planning for intracranial stereotactic radiosurgery of multiple metastases

Knowledge Based Radiotherapy (KBRT) or Knowledge Based Planning (KBP) has been suggested as a technique to help control the variation between patients’ radiotherapy treatments. In general KBP involves using an atlas of historical plans to inform the current treatment optimisation. It has been suggested as an aid for training, for clinical trials, and as part of the treatment planning process either for Quality Control or direct plan optimisation. KBP has been applied to a number of different planning techniques and modalities, and a number of different methods have been proposed and tested. Commercially RapidPlan™ is available for Varian Linac planning. Stereotactic Radiosurgery (SRS) involves using fewer but higher dose radiotherapy deliveries to achieve an ablative effect on tumours, and requires a greater degree of precision that conventionally fractionated radiotherapy. SRS is an important modality for treating intracranial metastatic lesions, as it has been shown to improve Quality of Life (QoL) compared to Whole Brain RT for patients with ≤4 metastases. SRS can be delivered on conventional linear accelerators, using GammaKnife™ (Elekta AB, Stockholm, Sweden) and CyberKnife™ (Accuray, Inc., Sunnyvale, CA, USA). KBP has been applied to SRS treatments with conventional treatment but to the author’s knowledge not to CyberKnife or GammaKnife planning. This work intends to develop a bespoke KBP platform for CyberKnife, investigating the different approaches in the context of the unique planning challenges of the modality.