ASTM E746-17

4.1 This standard provides a practice for RIQR evaluations of film and non-film imaging systems when exposed through an absorber material. Three alternate data evaluation methods are provided in Section 9. Determining RIQR requires the comparison of at least two radiographs or radiographic processes whereby the relative degree of image quality difference may be determined using the EPS plaque arrangement of Fig. 1 as a relative image quality indicator (RIQI). In conjunction with the RIQI, a specified radiographic technique or method must be established and carefully controlled for each radiographic process. This practice is designed to allow the determination of subtle changes in EPS that may arise to radiographic imaging system performance levels resultant from process improvements/changes or change of equipment attributes. This practice does not address relative unsharpness of a radiographic imaging system as provided in Practice E2002. The common element with any relative comparison is the use of the same RIQI arrangement for both processes under evaluation.

4.2 In addition to the standard evaluation method described in Section 9, there may be other techniques/methods in which the basic RIQR arrangement of Fig. 1 might be utilized to perform specialized assessments of relative image quality performance. For example, other radiographic variables can be altered to facilitate evaluations provided these differences are known and documented for both processes. Where multiple radiographic process variables are evaluated, it is incumbent upon the user of this practice to control those normal process attributes to the degree suitable for the application. Specialized RIQR techniques may also be useful with micro focus X-ray, isotope sources of radiation or with the use of non-film radiographic imaging systems. RIQR may also be useful in evaluating imaging systems with alternate materials (RIQI and base plate) such as plastic, copper-nickel, or aluminum. When using any of these specialized applications, the specific method or techniques used shall be as specified and approved by the cognizant engineering authority.

1.1 This standard provides a practice whereby industrial radiographic imaging systems may be comparatively assessed using the concept of relative image quality response (RIQR). The RIQR method presented within this practice is based upon the use of equivalent penetrameter sensitivity (EPS) described within Practice E1025 and subsection 5.3 of this practice. Figure 1 illustrates a relative image quality indicator (RIQI) that has four different plaque thicknesses (0.015, 0.010, 0.008, and 0.005 in.) sequentially positioned (from top to bottom) on an absorber plate of a specified material and thickness. The four plaques contain a total of 14 different arrays of penetrameter-type hole sizes designed to render varied conditions of threshold visibility when exposed to the appropriate radiation. Each “EPS” array consists of 30 identical holes; thus, providing the user with a quantity of threshold sensitivity levels suitable for relative image qualitative response comparisons. There are two standard materials (steel and plastic) specified herein for the RIQI and absorber. For special applications the user may design a non-standard RIQI-absorber configuration; however the RIQI configuration shall be controlled by a drawing similar to Fig. 1. Use of a non-standard RIQI-absorber configuration shall be described in the user’s written technique and approved by the CEO.