Abstract
The primary feature of x-ray image intensification is to allow a substantial reduction of the necessary x-ray dose, by offering a luminance gain of about 104 compared to direct view fluoroscopic screens. Such a luminance gain has made possible real time video recording and display of radiological images, by optically coupling a video camera to the output of the screen of the XRII tube. However, the observable field of view of the XRII was initially limited to approximately 15 cm, and the image resolution was not as good as the resolution achievable with radiological films. Progressively, the size of XRII tubes has been increased, and modern tubes can offer useful image diameters up to 40 cm. In addition to that, the electronic zoom, introduced at the beginning of the seventies as a feature of the XRII tubes, allowed the user to achieve an observable resolution very close to that of the radiological films, but at the expense of the observable field of view. Continuously, the manufacturing technology of the most critical parts of the XRII tubes have been improved resulting, for modern tubes, in such an imaging quality that most of the radiological modalities of diagnostic are directly achievable through video observation. Furthermore, the recent progress made in electronics and image processing offers powerful means to make the best possible use of the electronically recorded radiological images. A review is made, hereafter, of the latest progresses in XRII performances and applications.
