iaea human health series publications - SEDIM

7.2. WEEKLY TESTS7.2.1. Monitor quality control7.2.1.1. ScopeThe accuracy of the diagnosis and the efficiency of the radiologist are influenced by the conditions underwhich the mammograms are viewed. Viewing conditions can affect the diagnostic potential of even the best qualitymammograms. These conditions are determined by: the luminance and calibration of the monitors used for softcopy interpretation; the luminance of the viewboxes used for hard copy interpretation; the ambient roomillumination or the amount of light falling on the monitor and/or viewbox surface; and the quality of the masking offilms on the viewbox.Contrast is extremely important in the mammography image and is degraded by extraneous light.Consequently, monitors and viewboxes should be positioned to avoid incident light from windows, other monitorsor viewboxes, and other sources of bright light, either direct or reflected. General lighting in the room should bediffuse and at a low level.The monitor QC test should be performed on all primary medical display devices used to interpret digitalmammograms (radiologist workstations), and on all secondary display devices. Secondary display devices includethe monitor(s) attached to the acquisition workstation used to verify patient image quality and/or the monitor usedto manipulate and print the images (radiographer workstations). If the interpreting physicians provide finalinterpretations from hard copy only, the tests will only apply to the secondary display devices.A set of tests for evaluating the monitors is provided here. It should be noted that test procedures have alsobeen developed by manufacturers or as part of regional or national QC programmes [46], and these may provide asuitable (and possibly simpler) alternative to these tests.— Objective: To ensure that images on the acquisition workstation monitor and on the monitor used forinterpretation are displayed at adequate contrast and resolution.— Frequency: Weekly and after any service or maintenance of the workstations.7.2.1.2. Instrumentation(1) Modified TG18-QC (or SMPTE) test pattern with DICOM header to match processed images produced by eachacquisition system used at the site. This test pattern may be obtained from the manufacturer of the digitalmammography unit or the workstation. The images can be loaded as patient images in the same manner that priorpatient images are loaded for reviewing on the system. This could be from the PACS or from a CD provided bythe medical physicist, for example. These images should be stored on the system and should not be deleted.(2) Patient images.7.2.1.3. Methodology(a)Evaluating the monitors using test patterns(1) Before conducting this test, review the acceptable viewing conditions worksheet (see Chart 15 in Annex II)posted by the medical physicist in the room where the radiologist workstation is located.(2) Ensure that the lighting conditions and room configuration match those described on the worksheet. Ensurethat no sources of bright light are present in the room or are being reflected from viewboxes and/or monitorsurfaces.(3) If differences exist between the acceptable configuration and the current configuration, adjust the roomappropriately to ensure that viewing conditions are acceptable (i.e. turn off lights that should be off, closecurtains, etc.).(4) For each primary and secondary display device, view the modified TG18-QC pattern on each monitor used todisplay digital mammograms. For primary display devices, typically two monitors are used to display digitalmammograms (see note below).50