Do you know Radiography Testing Techniques Used in NDT？
Radiography Testing (RT) employs a various X-ray NDT techniques to detect and measure discontinuities in materials and structures of test object to ensure the quality of the product. These techniques can be categorized based on how the X-ray are introduced into the material and the specific modes and advanced methods used to enhance flaw detection and measurement.
Radiography requires a medium to capture and evaluate the image of a test subject. Traditionally, film was used. However, with advances in computer and medical radiographic technology, digital radiography (DR) and computed radiography (CR) techniques have become popular for industrial applications.
There are four primary methods used.
Film Radiography
The “traditional” technique of image acquisition.
Uses X-ray film as a negative to capture and store X-ray images.
An Image Quality Indicator (IQI) is used to show that the appropriate radiography quality level has been achieved.
The Radiography film requires processing (development) in a darkroom to view the image on a film viewer.
Computed Radiography (CR)
Uses a reusable phosphor plate instead of X-ray film.
Imaging plates contain photo stimulable phosphors that store radiation as a latent image and change it into electrical signal.
The signal is captured and converted to a digital image for viewing on a high-resolution monitor.
Acts as a transition from film radiography to digital radiography.
Digital Radiography (DR)
Uses flat panel X-ray detector (FPD)or X-ray Linear array detector(LAD) to display images directly by scanning and converting radiation into an electric charge and then into a digital image.
The electrical charge is sent to a workstation processor that assembles an image as a digital X-ray datas.
X-ray image display speed of DR is much faster than CR ,which is also called real-time X-ray inspection. Modern advances make RT a method of great importance for continued development of automation and artificial intelligence. With the continued growth of additive manufacturing, digital radiographic inspection provides easy ways to gather information regarding complex internal components that are otherwise inaccessible.
Computed Tomography
Well-know as industrial X-ray CT(computed tomography)
Uses a similar detector as digital radiography.
Multiple Radiography exposures are taken at different angles to create cross-sectional images.
The multiple slice X-ray images through collection and reconstruction software taken create a three Dimension Visualization voxel modeling of the test object.
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