Contrast-to-noise ratio comparison between X-ray fluorescence emission tomography and computed tomography

Area of Science:

• Medical Imaging
• Nanotechnology
• Biomedical Engineering

Background:

• Gold nanoparticles (GNPs) are utilized in various biomedical applications, necessitating sensitive detection methods.
• Computed tomography (CT) is a standard imaging modality, but its sensitivity for low concentrations of nanoparticles can be limited.
• X-ray fluorescence emission tomography (XFET) is an emerging technique with potential for high-contrast imaging.

Purpose of the Study:

• To compare X-ray fluorescence emission tomography (XFET) with computed tomography (CT) for detecting low concentrations of gold nanoparticles (GNPs) in soft tissue.
• To identify conditions where XFET outperforms energy-integrating CT (EICT) and photon-counting CT (PCCT).

Main Methods:

• Dose-matched Monte Carlo simulations for XFET and analytical fan-beam simulations for EICT and PCCT were employed.
• Numerical mouse and contrast-depth phantoms with varying GNP concentrations (0.05%–4% by weight) in soft tissue were imaged.
• Contrast-to-noise ratios (CNRs) and detection limits (Rose criterion) were quantified for each modality.

Main Results:

• XFET demonstrated significantly higher CNR values compared to both EICT and PCCT in the mouse phantom.
• XFET outperformed CT for superficial imaging depths ( $$ ) with gold concentrations at and above 0.5%.
• The surface detection limit for XFET was determined to be 0.44% at a dose of 16 mGy, compatible with in vivo imaging.

Conclusions:

• XFET offers a significant benefit for imaging low concentrations of gold at superficial depths.
• The study confirms the feasibility of XFET for in vivo metal mapping in preclinical imaging.
• XFET shows promise for enhanced detection of nanoparticles in soft tissue applications.