iaea human health series publications - SEDIM

8.10.1.5. Interpretation of results and conclusions(a)TG18-QC test pattern image(1) There should be no smearing or noticeable artefacts on the image. The greyscale ramps should appear smoothand continuous, without terracing or discontinuities. Artefacts might include diagonal lines, flickering,blotches, non-uniform greyscale ramps, straight lines that appear curved in the image and inappropriate brightor dark pixels.(2) Lines should appear straight, and the boxes should be square. The pattern should be centred in the activedisplay area.(3) All 16 luminance patches should be distinct from each other in shade, and the low contrast targets should bevisible in the image.(4) At least the letters ‘QUALITY CONT’ should be visible in each of the three regions of the TG18-QC imageon the primary display devices (radiologist workstations).(5) The 5% contrast squares in the image should be visible in both the dark (0–5%) and the light (95–100%)squares (areas marked F in Fig. 36).(6) For primary display devices, the finest (Nyquist) vertical and horizontal high contrast bars in the patternsshould be visible in all four corners and at the centre.(7) The length of the 50 mm line measured by the radiologist review workstation software should be between47.5 and 52.5 mm in both the horizontal and vertical directions.(8) The images on paired primary display monitors (i.e. radiologist workstations) should appear to be visuallyidentical (i.e. the same brightness and contrast).(b)Annotation accuracy(1) In contact mode, the annotation tool should indicate the test object sizes to within 10% of their true size. Sincethe MTF tool is not on the exact plane calibrated by the manufacturer, an adjustment to that plane may benecessary. Similar performance should be demonstrated in the magnification mode.(c)TG18-UNL test pattern images(1) The difference between the maximum and minimum luminance measurements taken on the TG18-UNL10image should be within 30% of their mean.(2) The difference between the maximum and minimum luminance measurements taken on the TG18-UNL80image should be within 30% of their mean.(3) There should be no excessively bright or dark regions, scratches, or bright or dark pixels noticeable whenviewing the TG18-UNL10 or TG18-UNL80 image.8.10.1.6. Recommendations and corrective actions(1) Monitors need to be serviced and recalibrated by qualified service personnel if any of the following problemsoccur with the TG18-QC pattern:— Noticeable artefacts are present.— Lines appear curved or ragged.— Squares are not square.— Greyscale ramps are not smooth and continuous.— The letters ‘QUALITY CONT’ are not visible against the backgrounds of dark grey, mid-grey and lightgrey.— Not all 16 luminance squares or low contrast targets are discernible.— The horizontal and vertical high contrast finest line pair patterns cannot be resolved.— Measured distances are not within 5% of the true values.— Paired monitors have visually different appearances.123