ASTM International

Standard Practice for Determining Relative Image Quality Response of Industrial Radiographic Imaging Systems
 N E746

Annotation

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 5.2 of this practice. Figure 1 illustrates a relative image quality indicator (RIQI) that has four different steel plaque thicknesses (.015, .010, .008, and .005 in.) sequentially positioned (from top to bottom) on a -in. thick steel plate. The four plaques contain a total of 14 different arrays of penetrameter-type hole sizes designed to render varied conditions of threshold visibility ranging from 1.92 % EPS (at the top) to .94 % EPS (at the bottom) when exposed to nominal 200 keV X-ray 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.

This practice is not intended to qualify the performance of a specific radiographic technique nor for assurance that a radiographic technique will detect specific discontinuities in a specimen undergoing radiographic examination. This practice is not intended to be used to classify or derive performance classification categories for radiographic imaging systems. For example, performance classifications of radiographic film systems may be found within Test Method E1815.

This practice contains an alternate provision whereby industrial radiographic imaging systems may be comparatively assessed using Lucite plastic material exposed to nominal 30 keV X-ray radiation. The RIQI for this alternate evaluation is also illustrated in Fig. 1, except the plaque and base plate materials are constructed of Lucite plastic in lieu of steel. EPS values for Lucite plastic are provided in Section 5 based upon the use of a 1 -in. thick Lucite base plate. For high-energy X-ray applications (4 to 25 MeV), Test Method E1735 provides a similar RIQR standard practice.