DQE analysis of CdTe and Si sensor Timepix3 detectors

Abstract In this study, the Detective Quantum Efficiency (DQE) was measured by calculating the DQE at zero-frequency, the modulation transfer function (MTF), and the noise power spectrum (NPS) for Timepix3 detectors (pixel size of 55 μm) equipped with 500 μm silicon (Si) sensor and 1mm Cadmium Telluride (CdTe) sensor, with a Tungsten X-ray tube of 40 kVp (narrow-spectrum series (N-series) with beam quality N-40). By comparing these parameters, the impact of sensor material on spatial resolution and noise characteristics was assessed. In this study the MTF, NPS and DQE parameters were calculated with datasets from two different acquisition modes; counting mode, where the particle hits are not clustered and Time of Arrival and Time over Threshold (energy) mode, where the particle hits are clustered and their center of mass (c.m.) is calculated. It was concluded that the c.m. dataset provided better MTF and NPS values leading to an improved DQE estimation. It was also possible to correct the charge sharing caused by fluorescence events in the CdTe sensor by identifying the clusters, reconstructing the energy of the initial particle and assigning this energy to the position of the initial hit that generated the fluorescent photon. It was shown that the CdTe sensor offers an overall better detector performance than the Si sensor for high-resolution imaging applications for the chosen energy range. Systems with higher DQE can produce images with better contrast and lower noise, making them ideal for dose-sensitive applications like medical imaging.