4.1 There are several factors affecting the quality of a CR image including the basic spatial resolution of the IP system, geometrical unsharpness, scatter and contrast sensitivity. There are several additional factors (for example, software and scanning parameters) that affect the accurate reading of images on exposed IPs using an optical scanner.

4.2 This practice is to be used to establish a characterization of CR system by performance levels on the basis of a normalized SNR, interpolated basic spatial detector resolution and EPS. The CR system performance levels in this practice do not refer to any particular manufacturers' imaging plates. A CR system performance level results from the use of a particular imaging plate together with the exposure conditions, standardized phantom, the scanner type, and software and the scanning parameters. This characterization system provides a means to compare differing CR technologies, as is common practice with film systems, which guides the user to the appropriate configuration, IP, and technique for the application at hand. The performance level selected may not match the imaging performance of a corresponding film class because of the difference in the spatial resolution and scatter sensitivity. Therefore, the user should always use IQIs for proof of contrast sensitivity and basic spatial resolution.

4.3 The measured performance parameters are presented in a characterization chart. This enables users to select specific CR systems by the different characterization data to find the best system for his specific application.

4.4 The quality factors can be determined most accurately by the tests described in this practice. Some of the system tests require special tools, which may not be available in user laboratories. Simpler tests are described for quality assurance and long term stability tests in Practice E2445.

4.5 Manufacturers of industrial CR systems or certification agencies will use this practice. Users of industrial CR systems may use Practice E2445 or perform some of the described tests and measurements outlined in this practice, provided that the required test equipment is used and the methodology is strictly followed. Any alternative methods or radiation qualities may be applied if equivalence to the methods of this practice is proven to the appropriate cognizant engineering organization.

4.6 The publication of CR system performance levels will enable specifying bodies and contracting parties to agree to particular system performance level, as a first step in arriving at the appropriate settings of a system, or the selection of a system. Confirmation of necessary image quality shall be achieved by using Practice E2033.