Characterization of a CdTe single-photon-counting detector for biomedical imaging applications

Purpose: The Eiger 2X CdTe 1 M−W (Dectris ltd, Baden, Switzerland) single photon counting detector was characterized for imaging applications at the biomedical beamline ID17 of the European Synchrotron Radiation Facility. Methods: Linearity, Modulation Transfer Function, Noise Power Spectrum and Detective Quantum Efficiency were measured as a function of photon energy and flux in the range 26–80 keV. Results: The linearity was confirmed in the flux range specified by Dectris and a detection efficiency higher than 60 % was measured for energies up to 80 keV. The spatial resolution was inferred from the Modulation Transfer Function and was found to be compatible with the pixel size of the detector (75 μm), except at energies just above the K-edge of Cd and Te where it reached 150 μm. The study of the Noise Power Spectrum showed a time-dependency in the response of the sensor, which is mitigated at low photon fluxes (<2⨯108 ph mm−2 s−1). Conclusions: This work was the first characterization of the Eiger 2X CdTe 1 M−W for imaging applications with monochromatic synchrotron radiation. The spatial resolution and the quantum efficiency are compatible with low-dose imaging applications.