This stepwedge is constructed of homogeneous, high purity aluminum and is designed to provide incremental exposures to x-ray film by the increased aluminum thicknesses in each step. The Gammex 117 provides a useful means of comparing the characteristic curve of various film/screen combinations, mAs reciprocity, and if done very carefully, sensitometry. For sensitometry totally independent of x-ray generator variation, use the dedicated sensitometers described on pages 19-21. Specifications:

• Construction High Purity Aluminum Alloy
• 11 Steps 3 mm high and 12.7 mm deep
• Dimensions 14x6 cm (5.5x2.4 in.), Weight 461 g (1 lb.)