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H Knedel

Publications and source records attributed to H Knedel.

4 recordsLinked to original sources
PubMed1990

[Minimum resolution at a given dose for quality assurance of x-ray pictures].

The Federal German Board of Physicians ("Bundesärztekammer") has recently issued guide principles for quality assurance in x-ray diagnosis. These include the basic measurements defining important image details, sensitivity of screen-film combinations and exposure times. The conditions required for meeting the guide principles were tested, using low contrast grids for simulating tissues. Practical consequences from these measurements for radiographic techniques and for the use of test grids in quality assurance are detailed.

Germany, West↗
PubMed1978

[New intensifying screens in clinical radiology III: Screen-film combinations in mammography (author's transl)].

An industrial film was compared with four commercially available screen-film combinations with respect to dose, definition and signal to noise ratio. The demanded minimum resolving power requires definition of an object of 100 micrometer size. However, the defined minimum object sizes are approx. 180 micrometer with close-distance projection and approx. 240 micrometer with greater distance. In this study, therefore, the signal to noise ratios were measured at defined object sizes of 5 lp/mm and 2 lp/mm. The screen-film combinations have approximately the same values as the industrial film for a size of 250 micrometer (2 lp/mm) or are definitely higher. The signal to noise ratio of the Alpha M combination is superior by 50%, although the sensitivity of the combination is 4 to 6 times greater. The signal to noise ratio of the MinR system in 25% higher than that of the industrial film, the required dose being lower by a factor of 8. This results in skin doses of 0.7 rads instead of 6 rads with tissue layers of 4.8 cm thickness.

Female↗