X Ray Image Density. Fat and muscle appear as shades of gray. Above 4 0 extremely bright viewing lights is necessary for evaluation.
Above 4 0 extremely bright viewing lights is necessary for evaluation. Image contrast or radiographic contrast is the difference in density between neighbouring regions on the image. Images are presented at a certain width and centre of hounsfield units displayed.
Industrial codes and standards typically require a radiograph to have a density between 2 0 and 4 0 for acceptable viewing with common film viewers.
Fat and muscle appear as shades of gray. While increased optical or radiographic density indicates that the image is darker an increase in tissue density will result in an image that is lighter. Theoretical x ray density molecular weight x number of molecules per unit cell volume of unit cell x avogadro s number. A radiograph that is too light has insufficient density to visualize the structures of the anatomic part figure 9 3.