4.1 This standard provides a guide for the other DDA standards (see Practices E2597, E2698, and E2737). It is not intended for use with computed radiography apparatus. Figure 1 describes how this standard is interrelated with the aforementioned standards.

FIG. 1 Flow Diagram Representing the Connection Between the Four DDA Standards

4.2 This guide is intended to assist the user to understand the definitions and corresponding performance parameters used in related standards as stated in 4.1 in order to make an informed decision on how a given DDA can be used in the target application.

4.3 This guide is also intended to assist cognizant engineering officers, prime manufacturers, and the general service and manufacturing customer base that may rely on DDAs to provide advanced radiological results so that these parties may set their own acceptance criteria for use of these DDAs by suppliers and shops to verify that their parts and structures are of sound integrity to enter into service.

4.4 The manufacturer characterization standard for DDA (see Practice E2597) serves as a starting point for the end user to select a DDA for the specific application at hand. DDA manufacturers and system integrators will provide DDA performance data using standardized geometry, X-ray beam spectra, and phantoms as prescribed in Practice E2597. The end user will look at these performance results and compare DDA metrics from various manufacturers and will decide on a DDA that can meet the specification required for inspection by the end user. See Sections 5 and 8 for a discussion on the characterization tests and guidelines for selection of DDAs for specific applications.

4.5 Practice E2698 is designed to assist the end user to set up the DDA with minimum requirements for radiological examinations. This standard will also help the user to get the required SNR, to set up the required magnification, and provides guidance for viewing and storage of radiographs. Discussion is also added to help the user with marking and identification of parts during radiological examinations.

4.6 Practice E2737 is designed to help the end user with a set of tests so that the stability of the performance of the DDA can be confirmed. Additional guidance is provided in this document to support this standard.

4.7 Figure 1 provides a summary of the interconnectivity of these four DDA standards.

4.8 DDAs may be used with significant success under a wide energy range, i.e. from 10 kV to 20 MeV if configured appropriately. However in this document some phantoms such as the duplex wire gauge (Practice E2002) may not give an accurate representation of the basic spatial resolution at energies above 600 kV.