Detective quantum efficiency of photon-counting CdTe and Si detectors for computed tomography: a simulation study

Area of Science:

• Medical Imaging Physics
• Detector Technology
• Photon-Counting CT

Background:

• Developing advanced photon-counting computed tomography (CT) detectors is crucial for improving imaging performance.
• Key detector parameters influencing performance include converter material, thickness, and pixel size.
• Understanding these parameters is essential for optimizing detector design for specific clinical applications.

Purpose of the Study:

• To evaluate the impact of detector parameters on photon-counting CT performance using a linear-systems framework.
• To compare realistic silicon (Si) and cadmium telluride (CdTe) detectors at low count rates.
• To analyze spatial and energy resolution effects on detective quantum efficiency (DQE) and material decomposition.

Main Methods:

• Utilized a linear-systems framework incorporating spatial and energy resolution.
• Employed Monte Carlo simulations for photon transport analysis.
• Compared CdTe detectors (0.5mm and 0.225mm pixels) and Si detectors (0.5mm pixels, 30/60mm thickness) with/without tungsten scatter blockers.

Main Results:

• CdTe detectors exhibited significantly higher DQE for detection tasks (28-41% and 5-29%) compared to Si detectors in a 300mm object at 120kVp.
• For two-material decomposition, CdTe showed comparable or lower DQE ( -2% to 11% and -31% to -54%) than Si detectors.
• Dual-spectrum acquisition was found to be beneficial when combined with these detectors.

Conclusions:

• CdTe detector systems offer superior performance for detection tasks in low-count rate photon-counting CT.
• Si detectors demonstrate better performance for material decomposition tasks compared to CdTe systems.
• Detector material choice is critical and application-dependent for optimizing photon-counting CT imaging.