Stereotactic radiosurgery for multiple brain metastases: Results of multi-centre benchmark planning studies

Publication date: Available online 30 December 2017
Source:Practical Radiation Oncology
Author(s): David J. Eaton, Jonathan Lee, Ian Paddick
PurposeStereotactic radiosurgery is indicated for treatment of multiple brain metastases. Various treatment platforms are available, but most comparisons are limited to single centre studies. As part of a national commissioning programme, benchmark planning cases were completed by 21 clinical centres, providing a unique dataset of current practice across a large number of providers and equipment platforms.Methods and MaterialsTwo brain metastases cases were provided, with images and structures pre-drawn, involving three and seven lesions. Centres produced plans according to their local practice, which were reviewed centrally using metrics for target coverage, selectivity, gradient fall-off and normal tissue sparing.Results50 plans were submitted, using 24 treatment platforms. 11 plans were revised following feedback, including two centres who acquired a new platform; and one other centre accepted a restriction of service. All centres prioritised coverage, with the prescription isodose covering ≥95% of 233/235 target volumes. Selectivity was much more variable, especially for smaller lesions, and when combined with poor gradient indices resulted in large volumes of normal tissue being irradiated. Tomotherapy submissions were outliers for either selectivity or gradient index, but other platforms could produce plans with relatively low gradient indices for larger lesion volumes. There was more variation among Varian and Elekta linac plans than for Gamma Knife and Cyberknife, and larger differences for smaller targets, both inter- and intra-treatment-platform. Doses to normal brain and brainstem were highest when margins were applied, but improvements were possible by re-planning alone.ConclusionsMulti-centre benchmarking exercises have highlighted some variation in clinical practice and priorities, with a few outliers. Most platforms are able to achieve comparable plans, except for the smallest volumes and when larger planning margins are used. The data will be used to progress standardisation and quality improvement of national services, and can provide useful guidance for centres worldwide.



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