The Fluoroscan imaging system in foot and ankle surgery.

lntraoperative image intensification has been used extensively since its introduction by Coltman in the 1 94Os.'n2 Modern x-ray image intensification devices based on these designs are essentially unchanged in design since that time. These devices rely upon an xray beam that excites an image tube screen with the production of photoelectrons. These electrons are electronically accelerated to impinge on a tungsten target producing x-rays which are focused onto a phosphorus screen, producing a visible image. This image is then focused onto a television camera. It is this image that the television camera scans and converts into a composite signal. The signal is then processed and converted into digital data and stored for retrieval by the surgeon. Instantaneous image retrieval without film processing reduces radiation exposure and is the great advantage of electronic image intensification. Recent refinements in image intensification technology include Fluoroscan (Fig. l), a miniature surgical Carm designed for use in the operating suite. The Fluoroscan real time digital imaging system is a low energy, high gain x-ray unit which takes advantage of a small field of view, small objectives (i.e., extremities such as ankles and wrists), and a high gain imaging chain to provide images without the risk associated with excessive radiation dose to medical personnel or the patient. By restricting the field of view and collimating the x-ray beam through a small aperture, radiation scattered to areas surrounding the unit is minimized. A high gain imaging chain is utilized to lower the x-ray quanta necessary to form a usable image. The manufacturer claims that under typical operating conditions, radiation to surgical personnel is less than 0.0001 R/hr.