What is the primary purpose of a 'density step wedge' in radiographic testing?

The primary purpose of a density step wedge in radiographic testing is to calibrate radiographic sensitivity. A density step wedge consists of a series of varying thicknesses or densities of a material that produce different levels of optical density on a radiographic film. By using the step wedge, radiographers can evaluate the sensitivity of the film or detector being used by comparing the different densities produced. This process helps in establishing the proper exposure settings required for accurate imaging, allowing for consistent and reliable results in radiographic testing.

Understanding the radiographic sensitivity is crucial for ensuring that the images obtained will have sufficient quality to interpret any defects or features within the tested material. By calibrating this sensitivity, technicians can better control factors such as exposure time, tube voltage, and film processing, leading to optimal radiographic outcomes.