Stereotactic radiosurgery for benign brain tumours: Results of multi-centre benchmark planning studies

Publication date: Available online 16 February 2018
Source:Practical Radiation Oncology
Author(s): David J. Eaton, Jonathan Lee, Rushil Patel, Antony E. Millin, Ian Paddick, Christopher Walker
PurposeStereotactic radiosurgery (SRS) is strongly indicated for treatment of surgically inaccessible benign brain tumours. Various treatment platforms are available, but few comparisons have included multiple centres. As part of a national commissioning programme, benchmark planning cases were completed by all clinical centres in the region.Methods and MaterialsFour benign cases were provided, with images and structures pre-delineated: intracanalicular vestibular schwannoma (VS), larger VS, skull base meningioma and secreting pituitary adenoma. Centres were asked to follow their local practice, and plans were reviewed centrally using metrics for target coverage, selectivity, gradient fall-off and normal tissue sparing.Results68 plans were submitted, using 18 different treatment platforms. 14 plans were subsequently revised following feedback, and review of 5 plans led to a restriction of service on 2 platforms (2 centres).Prescription doses were consistent for VS and meningioma submissions, but a wide range of doses were used for the pituitary case. All centres prioritised coverage, with the prescription isodose covering ≥95% of 78/82 target volumes. Lower values may be expected next to air cavities when using advanced algorithms, and in general may be acceptable for some benign lesions. Selectivity was much more variable, and in some cases this was combined with high gradient index and/or >1mm margin, resulting in large volumes of normal tissue being irradiated. Normal tissue doses were more variable across linac-based plans than Gamma Knife or Cyberknife, and dose spillage seemed independent of prescription isodose (inhomogeneity). This may reflect the variety of linac-based approaches represented, or the necessary trade-off between different objectives.ConclusionsThese benchmarking exercises have highlighted areas of different clinical practice and priorities, and potential for improvement. The subsequent sharing of plan data and margin philosophies between the neurosurgery and oncology communities allowed for meaningful comparison between centres and their peers.



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