Objective image quality assurance in cone-beam CT: Test methods, analysis, and workflow in longitudinal studies

Area of Science:

• Medical Imaging Technology
• Radiological Physics
• Quality Assurance in Medical Imaging

Background:

• Evolving standards for image quality (IQ) evaluation in multi-detector CT (MDCT) and cone-beam CT (CBCT) necessitate updated quality assurance (QA) methods.
• There is a growing need for rigorous QA with modern metrology and efficient workflows applicable to diverse MDCT and CBCT systems.

Purpose of the Study:

• To assess the feasibility and workflow of a unified image quality (IQ) assessment for MDCT and CBCT using a single phantom.
• To evaluate semiautomated analysis of quantitative IQ metrology for longitudinal studies.

Main Methods:

• A single test phantom was used for monthly IQ testing of seven scanners (three MDCT, four CBCT) over one year.
• Semiautomated software analyzed key IQ parameters including uniformity, linearity, contrast, noise, CNR, NPS, and MTF.
• Workflow optimization employed industrial engineering techniques (VSPM, SWL, SWCT) and evaluated DICOM data consistency.

Main Results:

• Quantitative IQ metrology, including NPS and MTF, provided insights into system failures (e.g., calibration issues).
• Monthly testing revealed IQ metric variations and established control limits for QA.
• Workflow analysis reduced total cycle time to approximately 10 minutes per system.
• Inconsistencies in DICOM data were noted for CBCT systems.

Conclusions:

• A versatile IQ phantom and testing methodology are effective for MDCT and CBCT QA.
• The streamlined workflow is practical for busy clinical environments.
• This approach supports consistent and reliable medical imaging quality.