Exhibit Hall | Forum 6
Purpose: To evaluate the clinical need for an automated decision-support software platform for Adaptive Radiation Therapy (ART) of Head-and-Neck cancer (HNC) patients.
Methods: We tested RTapp (SegAna), a new ART software platform for deciding when a treatment replan is needed, to investigate a set of 27 HNC patients’ data retrospectively. For each fraction, RTapp estimated dose distributions and cumulative doses received by targets and OARs from daily CBCT in real-time. RTapp also included a prediction algorithm that analyzed dosimetric parameters (DP) trends against user-specified thresholds to proactively trigger adaptation up to 4 fractions ahead. The DPs evaluated for ART were based on treatment planning dose constraints. Warning (V95<95%) and adaptation (V95<93%) thresholds were set for PTVs, while OAR adaptation endpoints of +10% (DE10) were set for all Dmax and Dmean DPs. Any threshold violation at end-of-treatment (EOT) triggered a review of DP trends to determine the threshold-crossing fraction Fx. The prediction model accuracy was determined as the difference between calculated and predicted DP values with 95% confidence intervals (CI95).
Results: RTapp identified 17/27 studies (63%) for violating PTV coverage or parotids Dmean at EOT. Eleven PTVs had V95<95% (mean coverage decrease of -6.8 ±3.0%) including 5 flagged for adaptation at median Fx=8 (range: 1-18). Seventeen parotids exceeded their Dmean constraints with a median increase of +2.95 Gy (range: 0.99-6.31Gy) at EOT, including 9 with DP>DE10. The differences between predicted and calculated PTV V95 and parotids Dmean was up to 7.6% (mean±CI95: -2.9±4.6%) and 5Gy (mean±CI95: +0.3±1.6Gy), respectively. For parotids, a median Fx of 5 ranged between 1-23 with a lack of specific trend demonstrating that the need for treatment adaptation may be verified for every fraction.
Conclusion: Integrated in an ART clinical workflow, RTapp aids in predicting whether specific treatment would require adaptation up to four fractions ahead of time.
Deformation, Image-guided Therapy, Software