We are happy to share that one of the most renowned cancer centers in the United States, Cedars Sinai Medical Center in Los Angeles, presented a remarkable new study on the Integral Quality Monitor (IQM) at the AAPM 2025 Annual Meeting in Washington, D.C..
The study, titled
“A Comparison of Segment-by-Segment Versus Cumulative Signal Evaluation for Patient-Specific QA using the IQM,”
represents an important step forward in real-time quality assurance for radiotherapy.
The Cedars Sinai research team analyzed 37 clinical VMAT treatment plans covering multiple anatomical regions—brain, spine, lung, and prostate—using IQM signal data acquired during real-time treatment delivery on an Elekta Versa HD linac. Both segment-by-segment and cumulative signal evaluations were performed and compared against calculated reference data to evaluate accuracy and reproducibility.
In addition, the study included validation using a SunNuclear ArcCheck device, ensuring a robust comparison across QA modalities.
While cumulative signal analysis is a standard part of IQM QA, this study brings something new to the table: comprehensive segment-by-segment analysis. This granularity provides more detailed insights into localized deviations that might otherwise remain undetected.
By evaluating over 12,000 individual VMAT segments, the study demonstrates how segment-by-segment monitoring can help identify subtle delivery issues that may impact patient safety and treatment efficacy.
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A mean absolute segment-level difference of 2.0 ± 0.53%, with pass rates of up to 97.5% within a 7% threshold.
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Cumulative signal comparison showed even tighter agreement, with a mean difference of 1.04 ± 0.52% and 91.7% pass rate at the 2% threshold.
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Independent validation using the ArcCheck array revealed a gamma pass rate of 97.6%, supporting the accuracy of IQM signal analysis.
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The results are consistent with earlier studies but push the field further by demonstrating the feasibility and clinical benefit of segment-by-segment evaluation.
The ability to pinpoint localized delivery discrepancies during complex VMAT treatments has the potential to further elevate patient safety. Segment-level QA could serve as an early warning system, improving confidence in every treatment fraction.
With increasing complexity in modern radiation therapy, such innovations are essential for delivering precise, individualized care.