The machines showed the image of the foot inside the shoe when a person stood over the x-ray tube. [One source says the x-ray tube was lead-shielded while another says it was shielded with 1 mm of aluminum.-most likely varied b model and year]. "Some units allowed the operator to select one of three different intensities: the highest intensity for men, the middle one for women and the lowest for children.
Some models had three viewing slots, where both the child, parent and clerk could view the image. "Fortunately, the X-rays did not continue directly through to the viewers' eyes, but were reflected by mirrors to the viewing ports. With repeated use of the fluoroscope with different pairs of shoes, an enterprising clerk could entice customers to find the perfect fit."
While potential dangers of radiation were known before the shoe-fitting fluoroscope was patented, 10,000 shoe-fitting fluoroscopes were being used in the 1940s. In 1951, the American Conference of Governmental Industrial Hygienists formed safety standards. The standard required that customers could not use the device more than 20 times a year or 5 times a fitting, and that "customers should have shoes on BOTH feet at the time of a fluoroscopic examination." 1960, the device was banned in 34 states.
The Museum of Quackery claims their fluoroscope on display was found in Madison, West Virginia in 1981 where it was still being used.