A Pilot Study of Simulation-Free Hippocampal-Avoidance Whole Brain Radiotherapy Using Diagnostic MRI-Based and Online Adaptive Planning

Kylie H Kang; Alex T Price; Francisco J Reynoso; Eric Laugeman; Eric D Morris; Pamela P Samson; Jiayi Huang; Shahed N Badiyan; Hyun Kim; Randall J Brenneman; Christopher D Abraham; Nels C Knutson; Lauren E Henke

doi:10.1016/j.ijrobp.2024.03.039

A Pilot Study of Simulation-Free Hippocampal-Avoidance Whole Brain Radiotherapy Using Diagnostic MRI-Based and Online Adaptive Planning

Int J Radiat Oncol Biol Phys. 2024 Apr 3:S0360-3016(24)00458-9. doi: 10.1016/j.ijrobp.2024.03.039. Online ahead of print.

Affiliations

¹ Washington University School of Medicine in St. Louis, Department of Radiation Oncology, St. Louis, MO.
² University Hospitals, Department of Radiation Oncology, Case Western Reserve University, Cleveland, OH.
³ University of Texas Southwestern Medical Center, Department of Radiation Oncology, Dallas, TX.
⁴ Banner MD Anderson Cancer Center at Banner North Colorado Medical Center, Greeley, CO.
⁵ University Hospitals, Department of Radiation Oncology, Case Western Reserve University, Cleveland, OH. Electronic address: lauren.henke@uhhospitals.org.

PMID: 38580083
DOI: 10.1016/j.ijrobp.2024.03.039

Abstract

Purpose: We aimed to demonstrate the clinical feasibility and safety of simulation-free hippocampal avoidance whole brain radiation therapy (HA-WBRT) in a pilot study (NCTXXX).

Materials/methods: Ten HA-WBRT candidates were enrolled for treatment on a commercially available computed tomography (CT)-guided linear accelerator with online adaptive capabilities. Planning structures were contoured on patient-specific diagnostic MRIs, which were registered to a CT of similar head shape, obtained from an atlas-based database (AB-CT). These patient-specific diagnostic MRI and AB-CT datasets were used for pre-plan calculation, using NRG-CC001 constraints. At first fraction, AB-CTs were used as primary datasets and deformed to patient-specific cone-beam CTs (CBCT) to give patient-matched density information. Brain, ventricle, and brainstem contours were matched through rigid translation and rotation to the corresponding anatomy on CBCT. Lens, optic nerve, and brain contours were manually edited based on CBCT visualization. Pre-plans were then re-optimized through online adaptation to create final, simulation-free plans, which were utilized if they met all objectives. Workflow tasks were timed. In addition, patients underwent CT-simulation to create immobilization devices and for prospective dosimetric comparison of simulation-free and simulation-based plans.

Results: Median time from MRI importation to completion of "pre-plan" was one week-day (range: 1-4). Median on-table workflow duration was 41 minutes (range: 34-70). NRG-CC001 constraints were achieved by 90% of the simulation-free plans. One patient's simulation-free plan failed a planning target volume (PTV) coverage objective (89% instead of 90% coverage); this was deemed acceptable for first-fraction delivery, with an offline replan used for subsequent fractions. Both simulation-free and simulation-CT-based plans otherwise met constraints, without clinically meaningful differences.

Conclusion: Simulation-free HA-WBRT using online ART is feasible, safe, and results in dosimetrically comparable treatment plans to simulation-CT-based workflows while providing convenience and time-savings for patients.