Clinical Practice-Based Failure Modes and Root Cause Analysis of Cone Beam CT-Guided Online Adaptive Radiotherapy of the Pelvis
by
, , , ,
Dandan Zheng
1,*
,
Michael Cummings
1,
Hong Zhang
1,
Alexander Podgorsak
1,
Fiona Li
1,
Olga Dona Lemus
2,
Matthew Webster
1,
Neil Joyce
1,
Erika Hagenbach
1,
Kevin Bylund
1,
Haoming Qiu
1,
Matthew Pacella
1,
Yuhchyau Chen
1 and
Sean Tanny
1 1
Department of Radiation Oncology, University of Rochester, Rochester, NY 14627, USA
2
Department of Radiation Oncology, University of Miami, Coral Gables, FL 33146, USA
*
Author to whom correspondence should be addressed.
Cancers 2025, 17(9), 1462; https://doi.org/10.3390/cancers17091462 (registering DOI)
Submission received: 26 February 2025
/
Revised: 22 April 2025
/
Accepted: 23 April 2025
/
Published: 26 April 2025
(This article belongs to the Special Issue New Approaches in Radiotherapy for Cancer)
Simple Summary
Cone beam computed tomography (CBCT)-guided online adaptive radiotherapy (oART) has introduced a paradigm shift in radiotherapy by enabling online plan adaptation based on daily anatomical changes. While its automation enables and streamlines workflow, our retrospective analysis of over 1000 pelvic oART sessions identified a range of failure modes (FMs) related to system-driven constraints, patient-specific anatomical variations, and treatment execution challenges. These included contouring mismatches, software-driven irregularities, intrafractional anatomy changes, and limitations in fallback plans. The system’s automated workflow reduces human variability but also introduces rigid constraints that, in certain cases, impact treatment accuracy. Addressing these challenges requires a multidisciplinary approach, continuous quality assurance, and ongoing refinements to automation protocols. This study provides a comprehensive clinical practice-based evaluation of the challenges associated with CBCT-guided oART and highlights key areas for future improvements in adaptive radiotherapy systems.
Abstract
Background/Objectives: Cone-beam computed tomography (CBCT)-guided online adaptive radiotherapy (oART) represents a significant advancement in radiation oncology, enabling on-couch plan adaptation to account for daily anatomical changes. While this automation improves precision and workflow efficiency, it also introduces new failure modes (FMs) and workflow irregularities. This study aimed to systematically evaluate the clinical and technical challenges associated with CBCT-guided oART implementation. Methods: We retrospectively analyzed over 1000 CBCT-guided oART sessions for pelvic malignancies performed at our institution. A multidisciplinary team conducted a comprehensive review to identify and classify FMs, followed by root cause analysis (RCA) to evaluate their impact on treatment safety, efficacy, and workflow robustness. Results: In addition to session-terminating FMs, we identified recurring failure modes across three major domains: (1) system-driven issues, such as rigid target localization and software-driven irregularities; (2) patient-driven challenges, including interfractional and intrafractional anatomical variations; and (3) treatment planning and execution failures, including excessive dose hotspots from field-of-view limitations. The system’s closed-loop automation, while streamlining processes, introduced rigid constraints in plan adaptation and fallback plan execution, occasionally leading to unintended dose discrepancies. Conclusions: This study provides a comprehensive clinical practice-based evaluation of CBCT-guided oART, highlighting system-specific failure modes and their implications. Addressing these challenges requires structured quality assurance processes, multidisciplinary collaboration, and continuous workflow refinement. Our findings contribute to the development of safer and more robust adaptive radiotherapy platforms and clinical workflows.
Keywords:
adaptive radiotherapy; failure modes; root cause analysis; CBCT; Ethos; prostate cancer; pelvis
