Characterization and comparison of direct and indirect converting X-ray detectors for non-destructive testing (NDT) in low-energy and high-resolution applications

Recent developments of direct converting X-ray detectors with good efficiency in the lower (10 keV) to the higher (>200 keV) energy ranges will become more and more of interest for applied non-destructive testing purposes. In this publication, we present different tests for characterization and comparison of detectors used in low-energy and high-resolution radioscopic and computed tomography applications. The characterization and application tests were performed on the direct converting X-ray detector Ajat DIC 100TL (Oy AJAT Ltd.) which is based on CdTe with a CMOS readout and the indirect converting X-ray detector C9311DK (Hamamatsu) which is based on CsI with a CMOS readout. The results of different characterization criteria on one hand valid for all detector types and applications like basic spatial resolution (BSR), MTF, SNR and efficiency and on the other hand criteria especially for NDT in designated application fields are presented and compared for the two detectors.