Material-dependent effects of x-ray pre-filtration on material decomposition in photon-counting CT

Area of Science:

• Medical Imaging Physics
• Radiological Sciences
• Computed Tomography Technology

Background:

• Photon-counting computed tomography (PCCT) offers advanced material decomposition (MD) capabilities.
• X-ray source filtration is a critical parameter influencing PCCT performance.
• Understanding filtration effects is crucial for optimizing material identification and quantification (MIQ).

Purpose of the Study:

• To characterize the influence of x-ray source filtration on MD performance in PCCT.
• To evaluate filtration effects across different filter materials (brass, copper, tin) and thicknesses.
• To assess performance with low-Z (iodine, barium) and high-Z (tantalum) contrast agents.

Main Methods:

• Scanned single- and dual-contrast phantoms with iodine, barium, and tantalum on a CdZnTe PCCT system.
• Utilized various pre-filtration conditions: no filter, brass, copper (Cu), and tin (Sn).
• Quantified MD performance using sensitivity, specificity, and quantification accuracy, complemented by visual assessments.

Main Results:

• Filtration effects were material-dependent.
• Brass filtration improved tantalum sensitivity and quantification but increased crosstalk.
• Copper and tin filtration enhanced tantalum performance but reduced specificity for both low- and high-Z agents at higher thicknesses.

Conclusions:

• Optimal PCCT filtration strategies are material-specific.
• Moderate filtration can enhance MIQ for high-Z agents (e.g., tantalum) while preserving specificity.
• Findings guide filter selection for PCCT MD applications, dual-contrast protocols, and clinical translation of high-Z agents.