When Wilhelm Roentgen presented his now-classic paper "On a New Kind of Rays" to the Wurzburg Physico-Medical Society in 1895, few people outside the scientific community appreciated the medical revolution that his discovery would soon launch. Although Roentgen would be showered with honours for his work on x-rays (including the first-ever Nobel prize in Physics in 1901), Thomas Edison was the one who first demonstrated the widescale benefits of x-ray technology. In time, he and his staff would also demonstrate its dangers as well.
Always open to finding new ways to make life better (and to make a profit), Edison began work on a more practical method of harnessing x-rays immediately after Roentgen's initial announcement. While the elaborate Crookes tube system that Roentgen used made for impressive laboratory demonstrations, hospitals and medical clinics would need something more compact and energy-efficient. Much like Marie Curie and her discovery of Radium, Roentgen refused to patent his discovery and placed it in the public domain since he wanted humanity "to benefit from practical applications of the same". That meant that Edison was free to experiment with x-rays and to develop the first working fluroscope using tungstate of calcium as opposed to Roentgen's barium platinocyanide apparatus. By 1896, Thomas Edison announced that the Edison X-ray tube was ready for market.
With his usual showmanship, Thomas Edison conducted a public exhibition of his new invention at the 1896 Electrical Exhibition in New York's Grand Central Palace. In a classic case of Murphy's law in action, Edison and his assistants personally installed the equipment for the initial showing only to find that some of the big inductance coils had been damaged in shipping. To have the fluoroscope ready in time for the grand opening on Monday, Edison and his staff worked all weekend to repair the equipment. As one assistant would admit later, "We worked continuously all through that Saturday night and all day Sunday until evening, when we finished the job. I don't remember ever being conscious of more muscles in my life. I guess Edison was tired also, but he took it very philosophically."
Despite the last-minute problems, the first public demonstration of the new Edison fluoroscope to the American people was an overwhelming success. Thousands of spectators lined up for a chance to see their own bones and one ecstatic patient even arranged for a medical x-ray on the operating table the day of Edison's exhibition. When one attendant dared to complain publicly that the fluoroscent screen was just a sheet of ground glass, Edison responded by hauling him on stage where he was forced to place his wrist in the fluoroscope to see his bones for himself. Edison's demonstration received enthusiastic media reviews including an article in the May 1896 issue of Century Magazine.
That same article also demonstrated a darker side to Edison's new technology, however. One of his assistants, glassmaker Clarence Madison Dally, suffered adverse effects from radiation exposure. As Edison noted in the article:
When the X-ray came up, I made the first fluoroscope, using tungstate of calcium. I also found that this tungstate could be put into a vacuum chamber of glass and fused to the inner walls of the chamber; and if the X-ray electrodes were let into the glass chamber and a proper vacuum was attained, you could get a fluorescent lamp of several candle-power. I started in to make a number of these lamps, but I soon found that the X-ray had affected poisonously my assistant, Mr. Dally, so that his hair came out and his flesh commenced to ulcerate. I then concluded it would not do, and that it would not be a very popular kind of light; so I dropped it
Unfortunately for Clarence Dally, the consequences of his radiation exposure didn't improve with time. By 1900, the radiation damage to his hands and face was bad enough for him to request more time off from work. The strange burns to his left hand also failed to heal properly. Since there were no previous cases of radiation exposure on record, the medical treatment that he received was largely experimental. Edison kept Dally on the payroll since the long hours spent working on the new fluroscope appeared directly responsible for his health problems. Despite radical skin grafts and the amputation of his left hand in 1902 to halt carcinoma, Dally's condition worsened. His death from mediastinal carcinoma in 1904 gave him the dubious honour of being the first American to die of radiation poisoning.
Shaken by Clarence Dally's death, Thomas Edison stopped all work on his fluoroscope. While other workers suffered from radiation effects (including Edison himself whose vision was affected), Dally was the only fatality. As Edison would later announce:
"Don't talk to me about X-rays," he said. "I am afraid of them. I stopped experimenting with them two years ago, when I came near to losing my eyesight and Dally, my assistant practically lost the use of both of his arms. I am afraid of radium and polonium too, and I don't want to monkey with them."
Despite Edison's public warnings about the dangers of indiscriminate x-ray use, the fluoroscope's value in medicine and industry quickly overcame any misgivings. The Radiological Society of North America (RSNA) was founded in 1915 to provide proper safeguards and prevent further tragedies. Still, that didn't stop more enterprising companies from searching for new ways to profit from fluroscope technology.
After Boston doctor Jacob Lowe first patented his fluoroscope for x-raying feet in 1919 for diagnosing patients' foot injuries, x-ray shoe-fitting machines quickly became a standard feature in many shoe stores on both sides of the Atlantic. The RSNA quickly protested the use of x-rays in shoe stores arguing that it "lowers the profession of radiology" but the "Foot-O-Scope" (patented as the Pedoscope in the U.K.) became enormously popular. The two largest manufacturers of shoe-fitting fluroscopes, the X-Ray Shoe Fitter Corporation of Milwaukee, Wisconsin and the Pedoscope Company in Great Britain sold thousands of units across the U.S., Canada and the U.K.
Just about every prominent shoe store had a unit and customers were often invited to use the viewfinder to watch their toes wiggle while the fluorscope was operating. Length of x-ray exposure varied according to a timer on the machine (typically twenty seconds but the timer allowed up to forty-five seconds). The x-ray intensity ranged according to the size of the foot and the only protection that customers and staff received was a thin aluminum filter. Not only were there no warnings about possible health issues relating to x-ray exposure but the devices were often marketed to parents as a way of ensuring proper foot care for their children (one advertising slogan was "They'll need their feet all through life"). The X-Ray Shoe Fitter Corporation had an aggressive advertising campaign stressing the ease and safety of their machines, including a Seal of Commendation from Parents' Magazine to highlight the benefits of x-ray technology in foot care. X-rays became downright glamourous during that early era so it was probably not surprising that Superman's creators endowed him with "X-ray vision" (along with every other power they could imagine).
More than twenty years would pass before medical researchers began taking a closer look at the potential hazards of shoe-fitting fluoroscopes. By the end of World War II and the beginning of the Atomic Age, cases of radiation exposure seen in survivors from Hiroshima and Nagasaki were reported in the medical literature and new concerns were raised about indiscriminate use of x-rays in non-medical settings. In one widely-cited 1950 article, researchers Leon Lewis and Paul E. Caplan concluded that "the shoe-fitting fluroscope is not an instrument with obvious hazardous potentialities. It has long been used and no direct clinical evidence of harm has yet been established" and x-ray machines continued to be a common sight in shoe stores. Still, with growing anecdotal evidence of shoe-store assistants developing skin problems from overexposure to x-rays, U.S. agencies began imposing stricter guidelines concerning safe exposure levels. Companies selling fluroscopes took the new regulations in stride and even boasted about their compliance in advertisements which suggested (incorrectly) that their machines were government approved.
While no obvious cases like Clarence Dally ever emerged over misuse of shoe-fitting fluroscopes (despite some incidents of basal cell foot carcinoma linked to x-ray use), the backlash had definitely set in by the 1960s. More than thirty-three states had banned the device by 1970 and other states insisted that only a qualified physician could operate x-ray machines for shoe-fitting. Having medical doctors run machines that had been previously seen as harmless was enough to discourage most parents from allowing their use on their children (or themselves). Companies selling the machines fought back vigorously, both in the U.S. and the U.K. with advertising campaigns intended to overcome suspected health risks but the tide had definitely turned. By the end of the 1970s, shoe-fitting fluoroscopes were gone from virtually every store (one was reported in Virginia as late as 1981).
As medical fads go, the x-ray craze was relatively benign despite more than a century passing since Wilhelm Roentgen's initial discovery (not counting Clarence Dally's tragic death). Although fluoroscopes are used by radiologists, in dental offices, and in industrial settings, modern safeguards help prevent health problems despite ongoing controversy over safe exposure levels. More unconventional x-ray applications such as the shoe-fitting fluoroscope have long since been phased out. Still, full-body x-ray scanners remain a common feature in airports and security checkpoints arond the world despite limited research on safe exposure levels. Whether the rationale for their use will prove to be as mythical as the "benefits" of the shoe-fitting fluoroscope will be for future generations to discover.