iaea human health series publications - SEDIM

8.11.1.5. Recommendations and corrective action(1) If the density steps are not distinct and/or the low contrast squares are not visible, the printer should berecalibrated to work with the current viewbox and ambient illuminance levels.(2) If a 5% square is not visible, the printer should be recalibrated.(3) The printer should be calibrated to match the DICOM soft copy GSDF when the films are read on theradiologist mammographic viewbox. The observed contrast/jnd difference ((ΔL/L)/(jnd n – jnd n–1 )) versusaverage jnd ((jnd n + jnd n–1 )/2) should be within 20% of the response described by the DICOM GSDF.(4) The luminance ratio (luminance dynamic range) of the film on the radiologist mammographic viewboxshould be at least 250:1.(5) The average number of jnds per luminance interval should be less than 3.(6) The maximum deviation from the average number of jnds per luminance interval should be less than 2.(7) The root mean square deviation from the average number of jnds per luminance interval should be less than 1.(8) If not all line pair patterns are distinct, the service person should be consulted.(9) Measured lengths of the horizontal and vertical rulers on the TG18-QC pattern should be within 5% of theactual values.(10) Measured lengths of the horizontal and vertical annotation lines on the film should be within 5% of theirintended values.(11) The average length of the TG18-QC rulers should be within 5% of the average length of the annotation lines.(12) It should be noted that new operating levels should not need to be set, except when major changes are madeto equipment. The printer should be re-calibrated to meet the expected operating levels when film orprocessing chemistry is changed.(13) If there are noticeable artefacts, the source should be identified and corrected.8.11.1.6. Time frame for corrective actionImmediately: Corrective action should be taken before any further patient films are printed.133