iaea human health series publications - SEDIM

7.3.3. Laser printer artefacts7.3.3.1. Scope— Objective: To ensure that there are no objectionable artefacts on printed films.— Frequency: Weekly is desirable; monthly or when the presence of artefacts is suspected is essential. The testis required only for sites printing hard copy mammograms.7.3.3.2. Instrumentation— Magnifying lens (4× to 5× magnification).— Densitometer.— Uniform test image such as the TG18-UNL80 pattern (Fig. 25), or a uniform mid-grey image generated by theprinter.7.3.3.3. Methodology(1) Print the uniform test image with a window level that gives an optical density of between 1.5 and 2.0.The window width should be set to maximum.(2) Examine the resulting film on the radiologist viewbox using a magnifying glass. Ensure that the image is ofuniform optical density, with no streaks, lines, specks or blotches.(3) Record the test results on the laser printer artefacts chart (Chart 11 in Annex I).(4) Record the outcome of the test on the monthly, quarterly and semi-annual checklist (Chart 2 in Annex I).7.3.3.4. Interpretation of results and conclusions(1) The resulting film should be of uniform optical density.(2) There should be no streaks, lines, specks, blotches or other objectionable artefacts on the film that in theopinion of the radiologist could interfere with the interpretation of a mammogram.FIG. 25. The TG18-UNL80 test pattern.68