Measurement of the modulation transfer function of digital X-ray detectors with an opaque edge-test device.
A variant of the edge method for the determination of the pre-sampled modulation transfer function (MTF) of digital X-ray imaging devices has been developed and accepted as the standard method in the novel DQE measurement standard IEC 62220-1. An opaque tungsten edge-test device accomplishes the ideal step-like profile of the incident X rays. The edge spread function is measured over a large region across the edge transition that enables an accurate MTF measurement including the 'low-frequency drop'. The method has been applied to different state-of-the-art X-ray imaging detectors, a computed radiography, a CsI-based indirect and an Se-based direct flat-panel detector. The MTF measurement results will be presented. In contrast to the opaque edge device, the commonly used semi-transparent edge-test devices produce scatter radiation that deteriorates the incident X-ray profile, which leads to a systematic overestimation of the MTF.
Illers
Hartmut
H
Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany. hartmut.illers@gsf.de
Buhr
Egbert
E
Günther-Kohfahl
Susanne
S
Neitzel
Ulrich
U
D002586:Cesium / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D007454:Iodides / Q000737:chemistry; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012643:Selenium / Q000737:chemistry; D012680:Sensitivity and Specificity; D014414:Tungsten; D014963:X-Ray Intensifying Screens; D014965:X-Rays
D007454:Iodides; D002586:Cesium; D012643:Selenium; C040050:cesium iodide; D014414:Tungsten