Radiation dose optimization for photon-counting CT coronary artery calcium scoring for different patient sizes: a...

Area of Science:

• Medical Imaging Physics
• Radiological Sciences
• Cardiovascular Imaging

Background:

• Coronary artery calcium (CAC) assessment is crucial for cardiovascular risk stratification.
• Optimizing radiation dose in computed tomography (CT) is an ongoing priority.
• Photon-counting CT (PCCT) offers potential advantages over conventional CT detectors.

Purpose of the Study:

• To evaluate the radiation dose reduction capabilities of PCCT for CAC assessments.
• To investigate the impact of varying tube potentials on dose and image quality across different patient sizes.
• To determine optimal PCCT parameters for effective dose reduction in CAC scoring.

Main Methods:

• A dynamic phantom simulating coronary arteries with varying calcification densities was used.
• Simulated average- and large-sized patients were created using extension rings.
• PCCT scans were performed at different tube potentials (70-140 kVp, including Sn100 kV) and reconstructed at 70 keV virtual monoenergetic energy, comparing to a 120 kVp reference protocol.

Main Results:

• A dose reduction of up to 22% was achieved at Sn100 kV for average-sized phantoms.
• Large-sized phantoms showed dose reductions of 19% (Sn100 kV) and 3% (Sn140 kV).
• Sn100 kV demonstrated no significant differences in Agatston scores or contrast-to-noise ratio (CNR) across all tested conditions.

Conclusions:

• PCCT with a tube voltage of 100 kV and tin filtration, reconstructed at 70 keV, enables significant radiation dose reduction (≥19%) for CAC assessment.
• This dose reduction is achievable irrespective of phantom size, CAC density, or simulated heart rate.
• Lowering tube voltage in PCCT is a viable strategy for reducing radiation exposure in CAC scoring without compromising diagnostic image quality.