Author: Deidre Batchelar, Michael Kudla, Stephanie Merkl, Tony Teke 👨🔬
Affiliation: BC Cancer - Kelowna 🌍
Purpose: Preplanning 3D-printed templates for cervical and vaginal brachytherapy is an iterative process, often taking hours to for an individual patient.
This study demonstrates an end-to-end automated pre-planning software, which generates a library of pre-plans, performing both needle search and dwell-time optimization. We show that pre-plans with robust needle trajectories and high-quality dosimetry can be generated very quickly.
Methods: The optimizer was evaluated on twenty-one interstitial GYN patients previously treated with 3D-printed cylinder templates. Ten patients were treated with tandem and cylinder and eleven with cylinder alone.
Needle trajectory and dwell-time optimization was performed for each patient using our optimization platform. For each patient, eight candidate needle trajectory solutions were generated, from which the plan with the most interstitial needles was selected automatically for dwell-time optimization.
Evaluation prescription was 30Gy/5 fractions. Objectives of HRCTV D90>650cGy, V100>95%, Bladder D2cm3<550cGy, Rectum and Sigmoid D2cm3<340cGy and Small Bowel D2cm3<225cGy were used, with target and OAR goals chosen to meet EMBRACE II EQD2 guidelines when combined with 45Gy/25 fractions of external radiation.
Results: Median optimization time per patient was 8.6 minutes(IQR 3.9,21.6). All pre-plans generated were clinically acceptable. The resulting plans had a median of 13(11,15) needles, and median HRCTV D90 of 6.2Gy(5.6,6.4), and V100 of 91.9%(83.2,94.0). Bladder, Rectum, Sigmoid, and Small Bowel D2cm3 (Gy) were 5.5(5.3,5.8), 3.9(3.1,4.5), 3.4(2.5,4.1), and 1.6(0.9,3.1) respectively.
Conclusion: A software suite for end-to-end treatment pre-planning for 3D-printable interstitial GYN BT templates has been demonstrated. 3D-printable needle trajectory plans and their resulting dosimetry can be generated in a single click, reducing treatment pre-planning time from hours to mere minutes, a significant saving of valuable clinician time. Plans generated can be sent directly for 3D printing or used as a starting point for further manual refinement in a commercial TPS.