[Effect of observation time on the perception of details in x-ray pictures]. / Der Einfluss der Betrachtungszeit auf die Wahrnehmung von Details im Röntgenbild.

The authors studied the influence of perception time on the quantified image quality of radiographs, using as an experimental basis the target presentation time during which there was no active involvement of the observer. No change in the influence on the observer was seen down to an observation time of 1 sec.; there was a slight but practically negligible drop on further reduction to 0.5 sec. At 0.1 sec. there was a drop that would have been approximately compensated by a contrast enhancement of object detail to about twice the original value. The influence of the perception time was placed in relation to an example of the influence of structured noise on the detection performance. This influence proved to be significantly greater than that of time. A comparison of the concept of "conspicuity" as defined by Revesz and Kundel was set in relation to the term "Auffälligkeit" ("distinctiveness") coined by Stender. It was established that the quality reserve QR after Borcke corresponds to "Auffälligkeit" as defined by Stender and should best be separated from image quality changes dues to the influence of structured noise on the detection of radiological abnormalities.

[The quality of the roentgen image--a recommendation for quantifying image quality]. / Die Qualität im Röntgenbild--Ein Vorschlag für eine Quantifizierung der Bildqualität.

A proposal is worked out to express x-ray image quality by means of a meaningful and practically useful numerical system. Attennations have been selected in such a manner that whole numbers of Quality Value figures ranging from -10 to +60 result in meaningful associations with radiological indications. Individual parameters are incorporated into the resulting values. A test body for determining Information Sensitivity figures is described that is practical easy built and inexpensive; its most important feature, however, is that it is reproducible and permits international comparisons. This test body provides a direct linking with the Quality Value figures.

[Image quality assurance in x-ray diagnostic units. Information on DIN 6868 standard series]. / Sicherung der Bildqualität in röntgendiagnostischen Betrieben. Informationen zur Normenreihe DIN 6868.

The Working Group for Standardisation justifies and comments on the establishment of a standard series for image quality assurance in X-ray diagnostic services (DIN 6868). In order to promote compliance with these standards, the users are given some background information on the structure of the standard series and on the recommended procedures to be followed. The definitions for the various hierarchically arranged tests, such as constancy test, status test, acceptance test as well as a definition for the term "base-line image quality" are explained.

[Image quality from direct radiological magnification (author's transl)]. / Bildgüteuntersuchung zur direkten röntgenologischen Vergrösserung.

An assessment of image quality from a direct radiological magnification method with a microfocus was carried out. It was found that direct magnification has advantages for the magnification of thin objects (5 cm. thickness). Because of the marked radiation scarrer in thick objects an improvement in picture quality is not possible. Scatter, despite the Groedel effect, is too large. Optimum results are obtained with a microfocus tube using universal screens. Comparable image quality is not possible with high intensification screens. High definition screens are not suitable for magnification. Dose measurements revealed unexpectedly low levels, particularly for thin objects. The reasons for this were examined and are described.