Is it possible for knowledge-based planning to improve intensity modulated radiation therapy plan quality for planners with different planning experiences in left-sided breast cancer patients?

Abstract

Background: Knowledge-based planning (KBP) is a promising technique that can improve plan quality and increase planning efficiency. However, no attempts have been made to extend the domain of KBP for planners with different planning experiences so far. The purpose of this study was to quantify the potential gains for planners with different planning experiences after implementing KBP in intensity modulated radiation therapy (IMRT) plans for left-sided breast cancer patients.

Methods: The model libraries were populated with 80 expert clinical plans from treated patients who previously received left-sided breast-conserving surgery and IMRT with simultaneously integrated boost. The libraries were created on the RapidPlan^TM. 6 planners with different planning experiences (2 beginner planners, 2 junior planners and 2 senior planners) generated manual and KBP optimized plans for additional 10 patients, similar to those included in the model libraries. The plan qualities were compared between manual and KBP plans.

Results: All plans were capable of achieving the prescription requirement. There were almost no statistically significant differences in terms of the planning target volume (PTV) coverage and dose conformality. It was demonstrated that the doses for most of organs-at-risk (OARs) were on average lower or equal in KBP plans compared to manual plans except for the senior planners, where the very small differences were not statistically significant. KBP data showed a systematic trend to have superior dose sparing at most parameters for the heart and ipsilateral lung. The observed decrease in the doses to these OARs could be achieved, particularly for the beginner and junior planners. Many differences were statistically significant.

Conclusions: It is feasible to generate acceptable IMRT plans after implementing KBP for left-sided breast cancer. KBP helps to effectively improve the quality of IMRT plans against the benchmark of manual plans for less experienced planners without any manual intervention. KBP showed promise for homogenizing the plan quality by transferring planning expertise from more experienced to less experienced planners.

Keywords: Breast cancer; Intensity modulated radiation therapy; Knowledge-based planning; Simultaneously integrated boost.

Fig. 1

The dose distributions for one representative patient on coronal planes of manual and KBP plans are shown in (a) and (b) for one beginner planner, (e) and (f) for one junior planner and (i) and (j) for one senior planner, respectively. (c), (g) and (k) display the dose differences between (a) and (b), (e) and (f) and (i) and (j), respectively. The dose-volume histograms are shown for (d) one beginner planner, (h) one junior planner and (l) one senior planner

Fig. 2

The box plots depicting the effect of KBP implementation on (a) the heart and (b) the ipsilateral lung dose for planners with each level of planning experiences. δ means the relative OAR dose deduction