Keywords:
Oncology, Cone beam CT, Dosimetry, Cancer
Authors:
N. Mitina, T. Peterson, R. Guidi, C. Hargrave
DOI:
10.26044/ranzcr2023/C-285
Conclusion
The results of this pilot study are subect to following limiting factors:
- Small sample size – in paticular once sub-catagorised into vertabral body level and complexity rating.
- Some volumes included in this study featured characteristics that may have affected the CI and GI values achieved. For example soft tissue extension of GTV, post surgical hardware, destructive lesions encompassing entire segments, rib involvment, additional adjacent previously treated PTVs.
- Date range for collected data – the departmental level of experience with planning VMAT SBRT spine lesions has changed over the seven year period in which the data has been collected. Additionally we have seen updates in machine technology altering our imaging capabilities in that time, in turn changing the CTV to PTV expansions amongst other considerations while planning.
Although preliminary in nature, there is an early indication of achievable and typical CI and GI amongst the plans in this cohort. These values appear to be affected by the size, location and complexity of the PTV volumes, for example the lower GI values for the HIGH complexity volumes are likely to be effected by large sized volumes in the cohort.
The future of this study includes collaborating with other departments in order to expand the sample size and encourage multicentre evaluations. As many details of optimal SBRT planning are still unknown, this collaboration will further support and improve the quality of stereotactic treatments. [7]
We intend to reoptimise characteristically similar spine lesion plans, limiting inter-planner variablitiy by maintaining planner experience level. Planning will be conducted with CI and GI goals as a benchmark and comparisons will be made of the overall quality of the dosimetry.
Ultimately, we would like to establish if knowing the achievable and desirable CI and GI values for these lesions will lead to greater planner confidence and time efficiency, as well as higher quality plans and improved outcomes.