[Quality control of Roentgen equipment with automatic exposure using a newly developed test phantom. Part II: surface...

The article reproduces further results of quality control tests conducted with 42 automatically exposed roentgenographs of a test phantom, for the parameters surface dose (Do), film-distant (AF) and film-proximal (AN) resolution, optical density of dominant (SDom), film contrast (KF) and size of focus. By means of definition of the quality number z = AN x AF/log10 x Do, it is possible to state the sequence of qualitatively different X-ray films and to plot this against log10 t to take organ movements into consideration, thus supplying a simple criterion of the quality of Roentgen equipment. Good equipment will yield values of z/log10 t = 3, whereas medium-quality and insufficiently equipped apparatus will yield values around 2 or 1, respectively, or even below this figure. If the values are too low, analysis of all data obtained with the test phantom will supply indications with regard to the possible causes. Of the 42 X-ray films tested in this study, the z/log10 t values were above 2 in 15 cases, and below 2 in the same number of cases. Variations in the size of focus, optical density of dominant and contrast, are shown in the diagrams and described quantitatively by their average values anad standard errors.