The mechanism, characteristics and recent trend of the various X-ray imaging sensors

In nondestructive inspections, the intensity distribution of the X-ray transmitted through an object is visualized. The high voltage of X-ray tubes ranges from 20 to 450 kV. Proper sensors for the visualization under various conditions have been developed and commercialized. Recently the performance of sensors has been much improved due to the progress of semiconductor production process, the speedup of data transmission interface, and the improvement of the speed and possible amount of the data in processing by personal computers. 'Sensors' are actually X-ray detectors including the photodiode array combine with scintillators, the X-ray film, the computed radiography, the scintillator plate camera, the X-ray CCD camera, the flat panel detector, and so on. Performance of these sensors, together with that of X-ray generator, will determine the quality of images. Each sensor involves specific technologies on materials, design, fabrication and inspection. Characteristics and recent trend of these sensors are presented. (J.P.N.)