Measurement of the Detective Quantum Efficiency (DQE) of digital X-ray imaging devices according to the standard IEC 62220-1

The DQEs of four digital X-ray detector systems have been measured in accordance with the new international standard IEC 62220-1: two CR detector systems of the same type, a CsI-based indirect flat panel detector and a selenium-based direct flat panel detector. A mobile measurement set-up complying with IEC 62220-1 has been realized. All equipment used was of a specific design, tested and calibrated. A standardized radiation quality (RQA5) was applied, and the air kerma at the detector entrance was varied between about 1 muGy and 20 muGy. The measurements of the two CR detector systems were performed at different sites using different X-ray generators/tubes and were in agreement within 0.02. The maximum DQE values were obtained for the lowest spatial frequency for which the DQE is required to be reported according to the IEC standard, i.e. at 0.5 mm(-1): The maximum DQE value measured was 0.21 for the CR systems, 0.42 for the indirect flat panel detector, and 0.31 for the direct Selenium-based detector. It has been demonstrated that the international standard IEC 62220-1 allows accurate and reliable measurements of the DQE to be conducted. It is now possible to objectively measure and compare DQE values of digital X-ray detector systems.