Establishing a Safety Net in X-Ray-Based Online Adaptive Radiation Therapy: Early Detection of Planning Deficiencies Through Upstream Physics Plan Review.

Abstract

Purpose: Online adaptive radiation therapy (oART) is increasingly adopted in clinics worldwide, making robust error mitigation essential to deliver high-quality treatment. This study reports on a one-year experience with an upstream physics plan review process aimed at early error detection and prevention of x-ray-based oART planning deficiencies.

Method/materials: An upstream plan review process was implemented, enabling physicists to evaluate adaptive plans before physician approval, with a focus on identifying deficiencies early and allowing time for corrective modifications. This process was facilitated by an ESAPI script, which recorded timestamps and comments in a central database. The review checklist, optimized through FMEA analysis and clinic-specific insights, was used for all oART plans. A total of 732 cases were reviewed prospectively and categorized into three groups-proceed, minor revisions necessary, and major revisions necessary-based on the type of errors found. Errors were further classified into sub-groups and reported. These findings were compared to events in the clinic's incident learning system to determine the impact of errors on treatment.

Results: Of the 732 cases (totaling 2437 oART deliveries), only 2 errors (0.3% of cases; 0.08% of deliveries) affected patient treatment, with no dosimetric consequences. The review process saved the clinic a net total of 160.3 hours over the year by reducing the need for last-minute re-plans. Approximately 29% of cases required minor or major revisions, largely due to contouring errors. Revision probability and upstream plan review time was significantly negatively correlated with the normalized planning workload (p < 0.001).

Conclusions: Upstream physics plan review enables early detection of planning deficiencies in oART, providing a critical safety net that prevents last-minute re-plans and enhances adaptive therapy reliability. Moving plan review earlier in the workflow supports quality assurance, workload efficiency, and error reduction, making it a valuable model for other treatment planning workflows.