The high and lowlight objects are used to set up the display monitor brightness and contrast prior to carrying out the other image quality checks, where the contrast and brilliance controls are accessible to the user.
The high contrast ring is used to check the system for signs of geometric distortion. The line pair resolution pattern is used to determine the limiting resolution of the system. The line pair pattern is incremented to measure spatial resolutions of between 0.5 and 5 line pairs per mm. It is manufactured from 100 um thickness of lead.The low contrast threshold spots are used to determine the ability of the fluorography system to discriminate between adjacent areas of low radiographic contrast. A total of 18 density spots using attenuating materials.