Routine kV-CBCT quality assurance in IGRT: Workflow-based comparison of QUART/MaximQA vs Catphan/ARTISCAN.

PURPOSE: The study aimed to compare image-quality metrics measured by two kV-CBCT QA systems-the QUART phantom with MaximQA and the Catphan phantom with ARTISCAN-using standard clinical kV-CBCT imaging protocols in a Varian TrueBeam IGRT setting, in line with AAPM TG-142/TG-179 QA recommendations.

METHODS

QA scans of the QUART and Catphan phantoms were acquired for image gently, head, thorax, pelvis and pelvis large imaging protocols. Key image quality metrics (noise, signal-to-noise ratio [SNR], uniformity, geometric distortion, Hounsfield unit [HU] constancy, contrast-to-noise ratio [CNR]) were measured using MaximQA and ARTISCAN software. Descriptive statistics and paired t-tests (α = 0.01) evaluated differences between systems; TG-142/TG-179 tolerances provided context.

RESULTS

The QUART/MaximQA system consistently produced significantly lower measured image noise and higher measured SNR than Catphan/ARTISCAN across most protocols (e.g., Pelvis Large: SNR 495.1 ± 40.7 vs 283.6 ± 31.5, p < 0.01). Geometric accuracy was excellent in both systems (measured distances ∼99.6%-100% of nominal, no significant differences). QUART phantom HU values were closer to nominal for inserts; however, the Catphan Solid Water insert was interpreted in terms of material-related HU behavior and stability rather than poorer HU accuracy (e.g., water-equivalent insert: QUART ≈ 0 HU vs +60 for Catphan/Solid Water, p < 0.01). Uniformity differences were small (< 5 HU) and often not significant. CNR and low-contrast detectability were reported as complementary QA indicators rather than directly equivalent metrics. Overall, both systems yielded image quality metrics within TG-142/TG-179 baselines.

CONCLUSIONS

Both QUART/MaximQA and Catphan/ARTISCAN provide consistent kV-CBCT QA metrics, but due to differences in phantom design, ROI definition, analysis software and setup conditions, their absolute values should not be considered directly interchangeable. The choice of phantom/software may influence absolute QA values. We recommend using institution-specific baselines per TG-142/TG-179 and cite emerging literature on automated kV-CBCT QA.