X-ray photograph taken by Wilhelm Roentgen of his wife's hand in December 1895. SSPL—Getty Images

The way the story goes, one of the earliest X-ray photographs ever taken (at left here) was not made for particularly scientific purposes. As TIME later reported, Wilhelm Roentgen, the scientist who devised the process, took a picture of his wife's hand "to make her appreciate the work he was doing and forgive him for having slighted her cooking."

It was on this day 120 years ago—Jan. 5, 1896—that an Austrian newspaper first reported Roentgen's discovery. In the decades that followed, many more images would follow Roentgen's wife's hand. Some of that photography was for scientific reasons , and some not so much . In the early days, X-Ray technicians would often burn themselves or suffer from overdoses of radiation." X - rays are literally death rays," TIME declared in 1941. "A man exposed to strong enough rays for a few minutes would die within a few months. A few seconds' exposure could cause temporary and possibly permanent sexual sterility, as well as severe blood changes. These and other effects can be cumulative, picked up fatally second by second through several years."

Despite the danger, however, the judicious use of X-rays allowed great medical progress in diagnosis and treatment alike—not to mention numerous non-medical uses.

Here are 15 vintage images of X-rays at work over the decades.