Assessing the Stability of Photon-Counting CT: Insights from a Two-Year Longitudinal Study

Area of Science:

• Medical Imaging
• Radiology
• Computed Tomography

Background:

• Photon-counting computed tomography (PCCT) offers advanced spectral imaging and reduced radiation dose.
• Long-term stability of PCCT is crucial for clinical applications, especially longitudinal studies, but remains largely unassessed.

Purpose of the Study:

• To comprehensively analyze the long-term quantitative stability of a first-generation clinical PCCT scanner over a two-year period.

Main Methods:

• Weekly identical experiments were performed using a consistent multi-energy CT protocol from November 2021 to November 2023.
• Software and hardware modifications were recorded, and tissue-mimicking inserts were scanned to assess Hounsfield Units (HU) and image noise in Virtual Monochromatic Images (VMIs) and iodine density maps.

Main Results:

• PCCT demonstrated consistent quantitative stability, with stable HU values in VMIs (e.g., 0.11% relative error for 70 keV VMI in single-source mode).
• Image noise remained stable, with minor fluctuations linked to software updates.
• Iodine density quantification showed stability and significant improvement, particularly in dual-source mode, with nominal errors decreasing from 1.44 to 0.03 mg/mL.

Conclusions:

• This study provides the first long-term reproducibility assessment of quantitative PCCT imaging.
• The findings highlight the robust stability of PCCT, supporting its potential for reliable clinical use, including longitudinal studies.