Quality of Industrial Radiography
The quality of the x-ray testing method or industrial radiography approach is dependent on many different factors:
Size/ thickness of material – if the size and thickness of the material is too large for radiation to penetrate through, it will not be able to detect any flaws or defects, or even capture the structural complexity of a part. If the part is too small or consists of low density material and the radiation exposure is too high, the resulting image may produce scatter.
Material – The more dense the material is, the more radiation it tends to absorb. When there are defects within a material such as cracks or voids, more radiation passes through them, which the detector captures and processes in the final resulting image. Since the cracks or voids do not absorb any radiation, they will appear with a higher density on the resulting image – darker on the greyscale value. The areas with high dense material will absorb radiation, therefore, it will appear lighter on the greyscale, when analyzing the resulting image. The radiation source has to be set up so that it is not too high or low for a particular material being scanned. High radiation exposure for low dense materials will develop a scattered image. Low radiation exposure for relatively high dense materials will not provide the details a project may require in a resulting image.
Orientation – Depending on the area that needs to be inspected for industrial applications, the orientation of the part in accordance with the x-ray or gamma source plays a big role. The orientation of the part in regards to the x-ray source is determined on the basis of the purpose of the test (to identify failures/defect/wall thickness etc.)
Contrast/sharpness/graininess – A minimum contrast is required in order to retrieve high quality images to analyze failures, such as porosity. Image contrast is the density variations between an area and the background density on the radiograph – if the contrast is clear, it will aid in realizing failures more accurately. Similarly, sharpness of the imaging results can help look into detail of the part deviations from initial design and certain defects. The graininess of an image can also determine whether the results are of quality. Aspects like the orientation, and radiation exposure may need to be adjusted in order to access better quality images.