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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Exposing the film to produce higher film densities will generally increase<br />
contrast. In other words, darker areas will increase in density faster than<br />
lighter areas because in any given period <strong>of</strong> time more x-rays are reaching<br />
the darker areas. Lead screens in the thickness range <strong>of</strong> 0.004 to 0.015 inch<br />
typically reduce scatter radiation at energy levels below 150, 000 volts. Above<br />
this point they will emit electrons to provide more exposure <strong>of</strong> the film to<br />
ionizing radiation thus increasing the density <strong>of</strong> the radiograph. Fluorescent<br />
screens produce visible light when exposed to radiation and this light further<br />
exposes the film.<br />
Charlie Chong/ Fion Zhang
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