Optimization of beam quality for photon-counting spectral computed tomography in head imaging: simulation study

Area of Science:

• Medical Imaging
• Radiological Physics
• Photon-Counting CT

Background:

• Head computed tomography (CT) is crucial for acute stroke evaluation.
• Photon-counting spectral detectors offer advanced capabilities for CT systems.
• Spectral information aids in artifact reduction and diagnostic accuracy.

Purpose of the Study:

• To determine optimal x-ray beam quality for material decomposition in head CT.
• To evaluate non-enhanced and K-edge imaging scenarios.
• To assess performance using figures of merit normalized by dose.

Main Methods:

• Utilized a head phantom with brain, bone, and skin layers.
• Investigated iodine and gadolinium contrast agents for K-edge imaging.
• Varied kVp settings, filter materials, and thicknesses to optimize beam quality.

Main Results:

• For non-enhanced imaging, 120-kVp with 2 HVL copper filter yielded best performance.
• For iodine K-edge imaging, optimal parameters varied by figure of merit, with a proposed tradeoff at 65 kVp.
• For gadolinium K-edge imaging, 120-kVp with 2 HVL thulium filter was optimal, showing higher signal-difference-to-noise ratio than iodine.

Conclusions:

• Optimal beam quality varies for non-enhanced versus K-edge imaging.
• Iodine may be preferable for K-edge imaging due to clinical concentration levels despite lower signal compared to gadolinium.
• Photon-counting spectral CT shows promise for improved head imaging diagnosis.