Fast and fully-automated multi-criterial treatment planning for adaptive HDR brachytherapy for locally advanced cervical cancer.

Abstract

To develop and evaluate a fast, automated multi-criterial treatment planning approach for adaptive high-dose-rate (HDR) intracavitary + interstitial brachytherapy (BT) for locally advanced cervical cancer. Twenty-two previously delivered single fraction MRI-based HDR treatment plans (SF_clin) were used to guide training of our in-house system for multi-criterial autoplanning, aiming for an autoplan quality superior to the training plans, while respecting the clinically desired "pear-shaped" dose distribution. Next, the configured algorithm was used to automatically generate treatment plans for 63 other fractions (SF_auto). The SF_auto plans were compared to the corresponding SF_clin plans in blind pairwise comparisons by an expert clinician. Then, the effect of adaptive autoplanning on total treatment (TT) plans (external beam + 3 BT fractions) was evaluated for 16 patients by simulating the clinically applied adaptive strategy to generate TT_auto plans and compare them with the corresponding clinical treatments (TT_clin). In the blind comparisons, all SF_auto plans were considered clinically acceptable. In 62/63 comparisons, SF_auto plans were considered at least as good as, or better than the corresponding SF_clin. The average optimization time for autoplanning was 20.5 ± 19.2 s (range 4.4-106.4 s) per plan. In 14 of 16 TT_auto plans, the desired total dose of 90 Gy (EQD₂) was obtained, compared to only 9 in the corresponding TT_clin, while autoplanning also decreased bladder and rectum doses. Fast, fully-automated multi-criterial treatment planning for adaptive HDR-BT for locally advanced cervical cancer is feasible. Autoplans were superior to corresponding clinical plans.