Fluoroscopy - History

History

The beginning of fluoroscopy can be traced back to 8 November 1895 when Wilhelm Röntgen noticed a barium platinocyanide screen fluorescing as a result of being exposed to what he would later call x-rays. Within months of this discovery, the first fluoroscopes were created. Early fluoroscopes were simply cardboard funnels, open at narrow end for the eyes of the observer, while the wide end was closed with a thin cardboard piece that had been coated on the inside with a layer of fluorescent metal salt. The fluoroscopic image obtained in this way is rather faint. Thomas Edison quickly discovered that calcium tungstate screens produced brighter images and is credited with designing and producing the first commercially available fluoroscope. In its infancy, many incorrectly predicted that the moving images from fluoroscopy would completely replace the still x-ray radiographs, but the superior diagnostic quality of the earlier radiographs prevented this from occurring.

Ignorance of the harmful effects of x-rays resulted in the absence of standard radiation safety procedures which are employed today. Scientists and physicians would often place their hands directly in the x-ray beam resulting in radiation burns. Edison's assistant Clarence Madison Dally (1865–1904) died as a result of exposure to radiation from fluoroscopes, and in 1903, Edison abandoned his work on fluoroscopes, saying "Don't talk to me about X-rays, I am afraid of them.". Trivial uses for the technology also resulted, including the shoe-fitting fluoroscope used by shoe stores in the 1930s-1950s.

Due to the limited light produced from the fluorescent screens, early radiologists were required to sit in a darkened room, in which the procedure was to be performed, accustomizing their eyes to the dark and thereby increasing their sensitivity to the light. The placement of the radiologist behind the screen resulted in significant radiation doses to the radiologist. Red adaptation goggles were developed by Wilhelm Trendelenburg in 1916 to address the problem of dark adaptation of the eyes, previously studied by Antoine Beclere. The resulting red light from the goggles' filtration correctly sensitized the physician's eyes prior to the procedure while still allowing him to receive enough light to function normally.

The development of the X-ray image intensifier by Westinghouse in the late 1940s in combination with closed circuit TV cameras in the 1950s revolutionized fluoroscopy. The red adaptation goggles became obsolete as image intensifiers allowed the light produced by the fluorescent screen to be amplified, allowing it to be seen even in a lighted room. The addition of the camera enabled viewing of the image on a monitor, allowing a radiologist to view the images in a separate room away from the risk of radiation exposure.

More modern improvements in screen phosphors, image intensifiers and even flat panel detectors have allowed for increased image quality while minimizing the radiation dose to the patient. Modern fluoroscopes use CsI screens and produce noise-limited images, ensuring that the minimal radiation dose results while still obtaining images of acceptable quality.