The Measurement and Evaluation of Standard DQE in Digital Radiography

Abstract

This study introduces the measurement and evaluation of the standard detective quantum efficiency in digital radiography. The detective quantum efficiency (DQE) is the most suitable parameter for describing the imaging performance of digital Radiography. DQE is defined as the squared ratio of the signal-to-noise ratio at the output to the signal-tonoise ratio at the input of digital radiography. In this study, the main work is to use some device to gain images, which used to obtain the modulation transfer function (MTF) and Noise Power Spectrum (NPS), according to the international standard IEC 62220-1. We also do some work about the algorithm of MTF and NPS. Finally we design a set of DQE assessment method which can be used in metrology and measurement of digital radiography. We define the test conditions as follows: RQA5 radiation quality, 21mmAl additional filtration. Experiment proved that DQE can show the basic properties of the flat panel detector in DR system. In the process of obtaining the DQE, the key performance parameters could be measured and normalized, which includes DQE, MTF, detector response curve and NPS. The digital radiography with poor DQE has the low imaging quality. The patients should have more body surface irradiation dose. Metrological verification and quality control personnel can determine the working station of DR system according to the indexes of DQE various performance indicators, which is good for decreasing collective effective dose equivalent. Keywords-Digital radiography, Flat panel detector, Detective quantum efficiency, Medical images measuring