Understanding NRT- Reading 1- 2 of 2- Radiogaphic Testing A
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
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Chapter 13: Controlling Radiographic Quality<br />
One <strong>of</strong> the methods <strong>of</strong> controlling the quality <strong>of</strong> a radiograph is through the<br />
use <strong>of</strong> image quality indicators (IQI). IQIs provide a means <strong>of</strong> visually<br />
informing the film interpreter <strong>of</strong> the contrast sensitivity and definition <strong>of</strong> the<br />
radiograph. The IQI indicates that a specified amount <strong>of</strong> material thickness<br />
change will be detectable in the radiograph, and that the radiograph has a<br />
certain level <strong>of</strong> definition so that the density changes are not lost due to<br />
unsharpness. Without such a reference point, consistency and quality could<br />
not be maintained and defects could go undetected.<br />
Image quality indicators take many shapes and forms due to the various<br />
codes or standards that invoke their use. In the United States two IQI styles<br />
are prevalent; the placard, or hole-type and the wire IQI. IQIs comes in a<br />
variety <strong>of</strong> material types so that one with radiation absorption characteristics<br />
similar to the material being radiographed can be used.<br />
Charlie Chong/ Fion Zhang
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