Author: Bin Cai, Andrew R. Godley, Brian A. Hrycushko, Heejung Kim, Mu-han Lin, David D.M. Parsons, Justin D. Visak, Da Wang, Tingliang Zhuang 👨🔬
Affiliation: Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, UT Southwestern Medical Center, University of Texas Southwestern Medical Center, Medical Artificial Intelligence and Automation (MAIA) Laboratory, Department of Radiation Oncology, UT Southwestern Medical Center, Department of Radiation Oncology, UT Southwestern Medical Center 🌍
Purpose: The standard radiation therapy workflow requires CT-simulation and planning, whether for initial treatments or re-planning due to significant anatomical changes. IPART instead uses one patient’s existing pre-plan for another patient, where the online ART system generates a new plan that accounts for anatomical difference between the two patients. This approach has the potential to eliminate the need for CT-simulation and planning, facilitating the start of initial treatment or fulfilling re-plan request from non-adaptive machines within a single day.
Methods: To demonstrate the feasibility of IPART strategy, we used a pre-clinical release version of the Ethos2.0 treatment planning system and its online ART emulator. With Ethos2.0 and Hypersight CBCT, direct online dose calculations for planning are made on the new CBCT. This eliminates the uncertainty associated with deformable registration between two different patients’ images required to created a synthetic CT for dose calculation. In this study, 45Gy dose in 25 fractions was prescribed to pelvic lymph nodes, uterus, vagina, and parametria. A previously treated patient with same prescription was selected as a reference case. A robust planning template was developed to ensure the success of online ART to be able to meet both OAR dose constraints and PTV coverage. Five additional test patients with the same prescription and treatment sites were adapted under the reference case’s preplan. PTV coverages and OARs doses were then evaluated.
Results: All five test patients achieved 95% PTV coverage, with no violations to dose constraints of bladder, rectum, bowels, cauda equina, and femoral heads.
Conclusion: This study demonstrates that the inter-patient ART is a clinically viable approach, completely free of CT-simulation and pre-planning process, thus enabling patients to proceed directly to treatment. This would significantly benefit urgent patients to start treatments same day or on-treat patients to receive an updated re-plan without pausing the treatments.