Characterization of CdZnTe semiconductor for applications in advanced computed tomography

Abstract

Cadmium zinc telluride (CdZnTe) is currently the only single crystalline semiconductor used in direct conversion gamma-cameras since CdZnTe can operate at room temperature, unlike other materials (e.g., germanium) that require liquid nitrogen cooling. Currently, CdZnTe-based single photon emission computed tomography (SPECT) cameras are successfully used in oncology and cardiology where they demonstrate diagnostic capabilities not achievable with indirect conversion SPECT technology. The extremely high energy resolution of CdZnTe is very promising for other spectroscopy applications including spectral CT (Computed Tomography). It has been shown that use of CdZnTe detectors in CT systems has the potential to improve image quality and diagnostic capabilities while reducing the radiation dose to a patient for a wide range of imaging tasks. However, state-of-the-art CT imaging systems operate at much larger x-ray flux rates than used in gamma cameras (up to 100 Mcps/mm2 in CT vs. 20-40 kcps/mm2 in nuclear medicine systems). High flux rate operation puts a stringent requirement on detector properties like electron and hole drift mobilities and uniformity of the internal electric field. [...]