Beam profile assessment in spectral CT scanners

Area of Science:

• Medical Physics
• Imaging Technology
• X-ray Optics

Background:

• Spectral computed tomography (CT) scanners require precise characterization of X-ray beam properties for accurate quantitative imaging.
• Existing methods may not fully capture spatial and temporal beam variations crucial for robust spectral CT performance.

Purpose of the Study:

• To present a novel method for assessing X-ray beam spatial and temporal properties in small-animal spectral scanners.
• To validate the method's effectiveness in identifying system performance issues and improving image reconstruction.

Main Methods:

• Combined experimental and modeled data to characterize X-ray beam profile shape, angular offset, and photon count differences.
• Assessed temporal stability via intra- and interscan count variations.
• Evaluated the method on spectral CT scanners with Medipix3RX-based detectors.

Main Results:

• Achieved integral count error of 0.5%, intrascan variation of 0.1%, and interscan variation < 1% on a calibrated system.
• Determined angular offsets ranging from 0.8° to 1.6° across studied scanners.
• Demonstrated the method's ability to detect system underperformance by analyzing beam profile deviations.

Conclusions:

• The developed method enhances spectral CT system monitoring for robust, quantitative imaging.
• Accurate beam offset parameters improve polychromatic image reconstruction, leading to better material discrimination and quantification.