Clinical implementation of a knowledge based planning tool for prostate VMAT

BackgroundA 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.MethodsA 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.ResultsPlans 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.ConclusionsThe 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.

[1]  Lei Dong,et al.  Late rectal toxicity on RTOG 94-06: analysis using a mixture Lyman model. , 2010, International journal of radiation oncology, biology, physics.

[2]  Eduard Schreibmann,et al.  Prior‐knowledge treatment planning for volumetric arc therapy using feature‐based database mining , 2014, Journal of applied clinical medical physics.

[3]  Russell H. Taylor,et al.  Patient geometry-driven information retrieval for IMRT treatment plan quality control. , 2009, Medical physics.

[4]  C. Fiorino,et al.  Clinical and dosimetric predictors of late rectal syndrome after 3D-CRT for localized prostate cancer: preliminary results of a multicenter prospective study. , 2008, International journal of radiation oncology, biology, physics.

[5]  Frederik Wenz,et al.  Knowledge-based radiation therapy (KBRT) treatment planning versus planning by experts: validation of a KBRT algorithm for prostate cancer treatment planning , 2015, Radiation oncology.

[6]  Johannes A Langendijk,et al.  Multicriteria optimization enables less experienced planners to efficiently produce high quality treatment plans in head and neck cancer radiotherapy , 2015, Radiation oncology.

[7]  Steve Webb,et al.  Assessing correlations between the spatial distribution of the dose to the rectal wall and late rectal toxicity after prostate radiotherapy: an analysis of data from the MRC RT01 trial (ISRCTN 47772397) , 2009, Physics in medicine and biology.

[8]  Linghong Zhou,et al.  An Automated Treatment Plan Quality Control Tool for Intensity-Modulated Radiation Therapy Using a Voxel-Weighting Factor-Based Re-Optimization Algorithm , 2016, PloS one.

[9]  Todd McNutt,et al.  A quality control model that uses PTV-rectal distances to predict the lowest achievable rectum dose, improves IMRT planning for patients with prostate cancer. , 2013, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[10]  J. Lo,et al.  A knowledge-based approach to improving and homogenizing intensity modulated radiation therapy planning quality among treatment centers: an example application to prostate cancer planning. , 2013, International journal of radiation oncology, biology, physics.

[11]  D. Low,et al.  Experience-based quality control of clinical intensity-modulated radiotherapy planning. , 2011, International Journal of Radiation Oncology, Biology, Physics.

[12]  Sasa Mutic,et al.  Predicting dose-volume histograms for organs-at-risk in IMRT planning. , 2012, Medical physics.

[13]  Steve Webb,et al.  Dose-volume constraints to reduce rectal side effects from prostate radiotherapy: evidence from MRC RT01 Trial ISRCTN 47772397. , 2010, International journal of radiation oncology, biology, physics.

[14]  R. Mohan,et al.  Do intermediate radiation doses contribute to late rectal toxicity? An analysis of data from radiation therapy oncology group protocol 94-06. , 2012, International journal of radiation oncology, biology, physics.

[15]  Yair Lotan,et al.  Predictors of rectal tolerance observed in a dose-escalated phase 1-2 trial of stereotactic body radiation therapy for prostate cancer. , 2014, International journal of radiation oncology, biology, physics.

[16]  J. Deasy,et al.  Radiation dose-volume effects in radiation-induced rectal injury. , 2010, International journal of radiation oncology, biology, physics.

[17]  J. Galvin,et al.  Preliminary toxicity analysis of 3-dimensional conformal radiation therapy versus intensity modulated radiation therapy on the high-dose arm of the Radiation Therapy Oncology Group 0126 prostate cancer trial. , 2013, International journal of radiation oncology, biology, physics.

[18]  Rasmus Bokrantz,et al.  Advantages and limitations of navigation-based multicriteria optimization (MCO) for localized prostate cancer IMRT planning. , 2014, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.