A methodology for incorporating a photon-counting CT system into routine clinical use

Area of Science:

• Medical Imaging Physics
• Radiological Technology

Background:

• Photon-counting computed tomography (PCCT) systems are emerging clinical tools following FDA approval.
• Integrating new PCCT systems with existing traditional CT fleets necessitates performance evaluation and harmonization.

Purpose of the Study:

• To devise a commissioning process for PCCT by evaluating its performance agreement with established clinical CT systems.
• To determine optimal PCCT reconstruction parameters for concordance with traditional CT systems.
• To assess the dose reduction potential of PCCT while maintaining image quality.

Main Methods:

• A Siemens NAEOTOM Alpha PCCT and a Siemens Force EID CT were evaluated using the ACR CT phantom.
• Image quality metrics (spatial resolution, noise texture) and dose metrics were assessed across various reconstruction kernels and iterative reconstruction (IR) strengths.
• Concordance was determined by calculating weighted differences in performance metrics between the two systems.

Main Results:

• Increasing kernel sharpness and IR strength generally increased spatial resolution, noise spatial frequency, and reference dose for both systems.
• Traditional EID CT showed higher spatial resolution than PCCT in standard mode for a given kernel.
• PCCT's IR implementation better preserved noise texture across IR strengths compared to EID CT.
• Optimal concordance was achieved by increasing PCCT kernel sharpness by one step and IR strength by 1-2 steps relative to EID CT settings.
• Targeting a constant noise magnitude revealed a dose reduction potential of up to 70% with PCCT.

Conclusions:

• A methodology for PCCT commissioning based on performance concordance with traditional CT systems was established.
• PCCT demonstrates significant dose reduction potential (up to 70%) while maintaining comparable image quality through optimized parameter selection.
• Specific adjustments in PCCT reconstruction parameters (kernel sharpness, IR strength) are required to achieve optimal agreement with traditional CT systems.