5.1 The gauge is intended to provide a means for measuring total image unsharpness and basic spatial image resolution as independently as practicable from the imaging system contrast sensitivity limitations. A similar description of the gauge’s construction may be found in ISO 19232-5. When the duplex gauge is positioned directly on the film or the digital detector without any test object between them, the total image unsharpness or basic spatial image resolution is equivalent to the inherent film or detector unsharpness (U_i) and the basic spatial detector resolution (SR_b^detector). Alternatively, line pair gauges with constant bar thickness of high attenuating material can be used to determine total image unsharpness and basic spatial resolution of radiologic imaging systems. They may produce different results up to one wire pair as compared to duplex wire measurements as described in this standard.

1.1 This practice covers the design and basic use of a gauge used to determine the total image unsharpness and the basic spatial resolution of film radiographs or of digital images taken with CR imaging plates, digital detector arrays, or radioscopic systems.

1.2 This practice is applicable to radiographic and radioscopic imaging systems utilizing X-ray and gamma ray radiation sources.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 The gauge described can be used effectively with tube voltages up to 600 kV. When using source voltages in the megavolt range the results may not be completely satisfactory.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.