Clinical implementation of a knowledge based planning tool for prostate VMAT
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RESEARCH
Open Access
Clinical implementation of a knowledge based planning tool for prostate VMAT Richard Powis1*, Andrew Bird1, Matthew Brennan1, Susan Hinks1, Hannah Newman1, Katie Reed1, John Sage1,2 and Gareth Webster1
Abstract Background: A knowledge based planning tool has been developed and implemented for prostate VMAT radiotherapy plans providing a target average rectum dose value based on previously achievable values for similar rectum/PTV overlap. The purpose of this planning tool is to highlight sub-optimal clinical plans and to improve plan quality and consistency. Methods: A historical cohort of 97 VMAT prostate plans was interrogated using a RayStation script and used to develop a local model for predicting optimum average rectum dose based on individual anatomy. A preliminary validation study was performed whereby historical plans identified as “optimal” and “sub-optimal” by the local model were replanned in a blinded study by four experienced planners and compared to the original clinical plan to assess whether any improvement in rectum dose was observed. The predictive model was then incorporated into a RayStation script and used as part of the clinical planning process. Planners were asked to use the script during planning to provide a patient specific prediction for optimum average rectum dose and to optimise the plan accordingly. Results: Plans identified as “sub-optimal” in the validation study observed a statistically significant improvement in average rectum dose compared to the clinical plan when replanned whereas plans that were identified as “optimal” observed no improvement when replanned. This provided confidence that the local model can identify plans that were suboptimal in terms of rectal sparing. Clinical implementation of the knowledge based planning tool reduced the population-averaged mean rectum dose by 5.6Gy. There was a small but statistically significant increase in total MU and femoral head dose and a reduction in conformity index. These did not affect the clinical acceptability of the plans and no significant changes to other plan quality metrics were observed. Conclusions: The knowledge-based planning tool has enabled substantial reductions in population-averaged mean rectum dose for prostate VMAT patients. This suggests plans are improved when planners receive quantitative feedback on plan quality against historical data. Keywords: Knowledge-based planning (KBP), Plan optimisation, Organ at risk dose sparing, Scripting
Background Volume Modulated Arc Therapy (VMAT) is a popular method of radiotherapy treatment delivery enabling high doses of radiation to be shaped to the treatment plan target volume (PTV) compared to conventional conformal radiotherapy techniques. VMAT plans are inherently complex and are typically produced in commercially * Correspondence: [email protected] 1 Worcestershire Oncology Centre, Worcestershire Acute Hospitals NHS Trust, Worcester, UK Full list of author information is available at the end of the article
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