Real-time radiography and radioscopy

What is NDT? 

An X-ray or neutron image can be formed on a fluorescent screen placed behind the specimen, which converts the X-rays to visible light. This is fluoroscopy. The image is usually rather faint and the method is now only used for thin non-metallic specimens.

If the conversion screen is built into a system incorporating a Silicon Intensified Tube camera or CCD device, then a much brighter real-time image can be viewed on a PC or television screen. The images are likely to be less sharp than those obtained on film and the flaw sensitivity reduced accordingly.

The image is either already composed of pixels or can be sub-divided to this level, digitised and stored in a computer framestore. Computer programs can then be used to improve the image. The images can be stored on video tape or disc. With such equipment, flaw sensitivities approaching those attainable on film are possible on some applications. The cost of film is eliminated and inspection speeds can be very high.

If a projected (enlarged) image is used with a television-fluoroscopic equipment, by means of a microfocus or minifocus X-ray tube, a further improvement in image quality is possible. The use of a television system in fluoroscopy reduces the radiation hazard to the operator, but the X-ray tube must still be protected. Robotic specimen handling is beginning to be used.