This is clever: after the Iron Curtain had dropped, Russians discovered they could use x-ray film, like an acetate or flexi disc, to pirate forbidden, decadent Western pop music. Gosh, how else were they gonna hear capitalist pig vocalists like Ella Fitzgerald or Elvis Presley?
Before the availability of the tape recorder and during the 1950s, when vinyl was scarce, people in the Soviet Union began making records of banned Western music on discarded x-rays. With the help of a special device, banned bootlegged jazz and rock ‘n’ roll records were “pressed” on thick radiographs salvaged from hospital waste bins and then cut into discs of 23-25 centimeters in diameter. “They would cut the X-ray into a crude circle with manicure scissors and use a cigarette to burn a hole,” says author Anya von Bremzen.
I'm not sure how they made these. The author says they used "a special device" to cut the grooves to make their "roentgenizdats." I can only speculate they used some type of cutting lathe; at the time, lathes were commonly used to cut audio onto acetates and most likely would have been around. As for their sound, the play back was about as good as a cheap flexi or home-cut acetate.