Imaging performance of a LaBr₃:Ce scintillation detector for photon counting x-ray computed tomography: Simulation...

Area of Science:

• Medical Imaging Physics
• Detector Technology
• Computed Tomography

Background:

• Photon-counting detectors (PCDs) are advancing X-ray computed tomography (CT) imaging.
• Current semiconductor PCDs like cadmium telluride (CdTe) face challenges with high cost and limited spectral signal-to-noise ratio (SNR).
• Lanthanum bromide doped with cerium (LaBr3:Ce) scintillators offer a potentially less expensive and fast alternative.

Purpose of the Study:

• To evaluate the performance of a LaBr3:Ce-based PCD for clinical X-ray CT applications.
• To compare LaBr3:Ce PCDs against traditional CdTe PCDs using Monte Carlo simulations.

Main Methods:

• Monte Carlo simulations were conducted comparing 3 mm LaBr3:Ce and 2 mm CdTe PCDs.
• Detectors were simulated using X-rays at 120 kVp and varying tube currents (20-1000 mA).
• Performance was assessed for spectral accuracy, counting capability, and spectral imaging tasks (conventional CT, water-bone decomposition, K-edge imaging) using normalized Cramér-Rao lower bounds (nCRLB).

Main Results:

• LaBr3:Ce PCDs demonstrated more accurate spectral measurements compared to CdTe, which suffered from spectral distortion.
• LaBr3:Ce PCDs exhibited lower dead times, particularly with the direct energy binning (DB) scheme.
• For water-bone decomposition and K-edge imaging, LaBr3:Ce with DB significantly outperformed CdTe, especially at higher tube currents, while CdTe showed better performance in conventional CT due to higher geometrical efficiency.

Conclusions:

• LaBr3:Ce PCDs with the DB scheme offer superior spectral imaging performance for material decomposition and K-edge imaging compared to CdTe.
• CdTe PCDs maintain an advantage in conventional CT imaging due to superior geometrical efficiency.
• LaBr3:Ce PCDs, particularly with the DB scheme, represent a viable and potentially cost-effective alternative to CdTe PCDs for advanced CT applications.