2256 - Clinical Viability of Inter-Patient Adaptive Radiotherapy (IPART): Enabling Seamless Re-Planning and Immediate Treatment Access

02:30pm - 04:00pm PT

Hall F

Screen: 4

POSTER

Presenter(s)

Da Wang, PhD - UT Southwestern Medical Center, Dallas, TX

D. Wang¹, B. A. Hrycushko², T. Zhuang³, D. D. M. Parsons³, A. R. Godley⁴, J. Visak³, H. Kim³, B. Cai³, and M. H. Lin³; ¹UT Southwestern Medical Center, Dallas, TX, ²Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX, ³Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, ⁴Medical Artificial Intelligence and Automation (MAIA) Lab, Dallas, TX

Purpose/Objective(s):

The standard radiation therapy workflow requires CT simulation and planning before initiating treatments. During the course of treatments, many patients may require re-planning due to tumor response, significant anatomical changes, or defects of immobilization devices. This necessitates another round of CT simulation and re-planning. The Inter-Patient Adaptive Radiotherapy (IPART) approach address this by utilizing an existing preplan from a previous patient to adapt a new patient, where the online Adaptive Radiotherapy (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, enabling the starts of initial treatment or fulfilling re-plan requests within a single day.

Materials/Methods:

To demonstrate the feasibility of our IPART strategy, we used a pre-clinical release version of the Ethos Emulator 2.0 treatment planning system and its online ART emulator. With Ethos 2.0 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 needed to created a synthetic CT for dose calculation. In this study, 45 Gy 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, meeting 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. The OARs evaluated in these cases were bladder, rectum, bowel bag, bowel loop, spinal cord, and femoral heads. All OARs dose constraints were met, with no violations were observed.

Conclusion:

This study demonstrates that the inter-patient ART is a clinically viable approach, completely free of CT simulation and planning process, enabling same-day treatment for new patients and re-planning for on-treat patients. It improves clinical efficiency by eliminating repetitive tasks, and allows rapid, seamless transitions to ART even for patients initially planned on non-ART platforms, offering broad benefit for patient care.