Relevance of Radiographic Resolution Capacity

Abstract

Resolution capacity is traditionally evaluated by radiography of metal objects (lead bar grids or fine slits). These objects yield high image contrast. Resolution, then, is limited by the sideways spread of information as expressed by the MTF. However, biologic objects of fine dimensions give rise to much less image contrast than the test objects of metal. Since the amplitude of the signals thus becomes reduced the signal/noise ratio in fact limits resolution capacity much more effectively than does the sideways spread of information. Thus, the MTF expresses a property of the radiographic system which appears only rarely to affect the information capacity of clinical radiographic images.

A Three-Contrast, Metal Test Pattern (Snellen E-Plate) in Evaluation of Imaging Techniques in Clinical Chest Radiography

“…The test plate has been used in several comparisons of radiographic techniques for clinical radiography (8,11,19,23), but the relationship of the E-plate detectability with the diagnostic usefulness of the radiographs has been poorly assessed. In general, the use of high-contrast test plates made of metal, to compare imaging chains for clinical radiography, has been criticized (15,22). On the other hand, this particular test plate has a wide contrast range planned to cover the practical contrast area used in ordinary clinical radiography (8).…”