Prediction of multi-criteria optimization (MCO) parameter efficiency in volumetric modulated arc therapy (VMAT) treatment planning using machine learning (ML)

Purpose: To predict the impact of optimization parameter changes on dosimetric plan quality criteria in multicriteria optimized volumetric-modulated-arc therapy (VMAT) planning prior to optimization using machine learning (ML). Methods: A data base comprising a total of 21,266 VMAT treatment plans for 44 cranial and 18 spinal patient geometries was generated. The underlying optimization algorithm is governed by three highly composite parameters which model a combination of important aspects of the solution. Patient geometries were parametrized via volume- and shape properties of the voxel objects and overlap-volume histograms (OVH) of the planningtarget-volume (PTV) and a relevant organ-at-risk (OAR). The impact of changes in one of the three optimization parameters on the maximally achievable value range of five dosimetric properties of the resulting dose distributions was studied. To predict the extent of this impact based on patient geometry, treatment site, and current parameter settings prior to optimization, three different ML-models were trained and tested. Precision-recall curves, as well as the area-under-curve (AUC) of the resulting receiver-operator-characteristic (ROC) curves were analyzed for model assessment. Results: Successful identification of parameter regions resulting in a high variability of dosimetric plan properties depended on the choice of geometry features, the treatment indication and the plan property under investigation. AUC values between 0.82 and 0.99 could be achieved. The best average-precision (AP) values obtained from the corresponding precision/recall curves ranged from 0.71 to 0.99. Conclusions: Machine learning models trained on a database of pre-optimized treatment plans can help finding relevant optimization parameter ranges prior to optimization.

Automated summary

This study used machine learning models trained on a database of pre-optimized treatment plans to identify relevant optimization parameter ranges and predict their impact on dosimetric plan quality criteria. Successfully identifying parameter regions resulting in significant variability of dosimetric plan properties depended on geometry features, treatment indication, and plan property under investigation. Model assessment showed AUC values between 0.82 and 0.99, with the best average precision values ranging from 0.71 to 0.99.