Digital radiography (DR) is an advanced form of x-ray inspection which produces a digital radiographic image instantly on a computer. This technique uses x-ray sensitive plates to capture data during object examination, which is immediately transferred to a computer without the use of an intermediate cassette. The incident x-ray radiation is converted into an equivalent electric charge and then to a digital image through a detector sensor.
Compared to other imaging devices, flat panel detectors, also known as digital detector arrays (DDAs) provide high quality digital images. They can have better signal-to-noise ratio and improved dynamic range, which, in turn, provides high sensitivity for radiographic applications.
Digital detection is based on the conversion of absorbed X-ray energy into electrical charge, which must then be represented digitally in grayscale images to show the quantified X-ray energy that was absorbed at each point in the digital image. The final image is produced using processing software. The purpose of image processing is to improve image quality by reducing noise, eliminating artifacts, and enhancing contrast if necessary.
Final images are stored digitally on storage media for viewing on a computer. While being viewed, the images may be zoomed, measured, for distance and angle, panned or windowed. Images can be sent to other computers for remote viewing, or linked to digital record systems for improved retrieval and diagnosis.
The basic principle, therefore, is to detect X-rays, then convert the X-rays to charge directly or indirectly (via conversion to light as the first step by phosphors or scintillators). These images are processed and viewed digitally. The process takes 10 seconds or less, and requires no cassette.
IVP: An IVP (intravenous pyelogram ) is an imaging test used to look at the kidneys and ureters. The ureters are the narrow tubes that carry urine from the kidneys to the bladder. During the test, the radiologist injects a contrast dye into one of your veins. During an IVP, contrast dye is injected into a vein using an intravenous (IV) line. The dye travels through your bloodstream to your kidneys, which filter it out. The dye collects in the organs of your urinary tract and makes them look bright white on the x-rays.
MCU: An MCU (Micturating Cysto-Urethrogram)is an x-ray test of the bladder as it fills and empties. It checks to see if the urine is flowing backwards from the bladder up towards the kidneys.
Barium Studies: Barium tests are used to examine the digestive tract using a white powder called barium sulphate. This powder can be seen on x-rays. For a barium swallow or barium meal, the barium sulphate powder is mixed with water (and sometimes flavouring) then swallowed. X-rays are taken as you swallow the mixture.
Digital radiography offer many advantages to the non-destructive testing community, including:
Shorter exposure times
Real-time applications
Use of analysis tool and defect recognition software
Improved detail detectability
Enhanced SNR and linearity
Reduced inspection time, as no chemical processing of film is required
Eliminates processing chemical, hence safe for environment
Digital image enhancement and data storage
Higher productivity
Portability
Increased dynamic range enables multiple thickness to be inspected in one shot
Immediate feedback
Easy to transfer to customers electronically
