3649 - Implementing Advanced Total Body Irradiation (TBI) Techniques into Clinical Trials: An NRG Hematologic Malignancies Working Group Survey
Presenter(s)
N. Kovalchuk1, E. A. Simiele2, M. J. LaRiviere3, S. M. Hiniker4, C. Han5, S. V. Dandapani5, J. Y. C. Wong5, M. Soike6, B. Guo7, S. Cherian7, D. Shrestha8, J. R. Teruel9, N. K. Gerber10, D. D. M. Parsons11, K. A. Kumar11, K. Latifi12, N. B. Figura12, Y. Xiao13, B. S. Hoppe8, and S. A. Milgrom14; 1Department of Radiation Oncology, Stanford University, Stanford, CA, 2University of Alabama Birmingham School of Medicine, Birmingham, AL, 3Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA, 4Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 5Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, 6Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, 7Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, OH, 8Mayo Clinic, Jacksonville, FL, 9Department of Radiation Oncology, NYU Langone Health, New York, NY, 10New York University Grossman School of Medicine, Department of Radiation Oncology, New York, NY, 11Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 12H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL, 13Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 14University of Colorado, Department of Radiation Oncology, Aurora, CO
Purpose/Objective(s): Total body irradiation (TBI) is an important component of stem cell transplantation that has historically been delivered using a two-dimensional technique. As intensity modulated radiation therapy is being used with increasing frequency for TBI delivery (IMRT TBI), it is necessary to standardize this technique for incorporation into NCTN clinical trials.
Materials/Methods: Following approval of the NRG Hematologic Malignancies Working Group, members of the group and invited experts in IMRT TBI developed a survey of 47 questions that was sent to participating institutions to assess current treatment planning and delivery practices.
Results: Eight institutions currently treating patients with IMRT TBI participated in the survey, including eight medical physicists and eight radiation oncologists. Experience with IMRT TBI ranged from 14 years to recent adoption, with participating centers collectively having treated approximately 750 adult and pediatric patients. The survey revealed significant variability in clinical practices across institutions, including differences in treatment delivery systems, rotational platform use, and planning techniques. Common treatment approaches included VMAT to the upper body combined with AP/PA to the lower body. The average number of isocenters ranged from 3 to 9. There were some commonalities among 75% of institutions, including lower dose rates for lung fields of 100-200 MU/min and lack of bolus application during IMRT TBI treatment. Given the technical complexity, automation was used by most institutions (100% used auto-segmentation and 50% used auto-planning). Planning target volume (PTV) definitions and organ-at-risk (OAR) sparing varied, with 75% of institutions sparing the lungs, kidneys, and lenses, and 37% of institutions also sparing the heart. Constraints for OARs were consistent, with most institutions requiring lungs Dmean < 8 Gy, kidneys Dmean < 6–7 Gy, and lenses Dmax < 90% of prescription. CBCT or orthogonal kV imaging was primarily used for setup verification.
Conclusion: This survey revealed considerable variability in IMRT TBI practices across institutions, underscoring the need for standardized protocols to ensure consistency in clinical trials. Despite differences, common practices in dose constraints, QA methods, and treatment delivery were identified, forming the basis for a consensus template that will be created by this working group. This initiative represents a critical step toward harmonizing IMRT TBI approaches, enhancing treatment quality, and facilitating robust clinical trial implementation and consensus guideline formation.