Why would anyone do this? The author puts it out there pretty clearly:
For some time I've been fascinated with the idea of reproducing these types of images in my home lab without great cost and with relative safety. As a collector of radioactive minerals and other ephemera, I decided that I wanted to use naturally radioactive materials as the source for my 'penetrating rays' rather than an amateur electrical x-ray machine setup.
Polaroid film is readily available and it develops itself. However, a workable technique needed to be developed. How to expose the film for hours or days without the need for absolute darkness? How would I develop the film reliably after an exposure was made?
The answer came from Kevin Clark of the Yahoo group, "GeigerCounterEnthusiasts". It was here that Clark explained his simple, yet reliable, technique for creating inexpensive Polaradiographs.
Items you'll need:
1. A Polaroid SX-70, Type 600, or Spectra camera
2. A package of unexposed Type 600 or Spectra Polaroid film
3. One metal cookie tin at least six inches in diameter
4. A few sheets/roll of aluminum foil
5. Radioactive material
That radioactive material can include:
- Old, unused lantern mantles
- Salt substitute or certain rock salts (Potassium Chloride)
- Vaseline glass (plates, cups, or marbles)
- Fiestaware plates and dishes
- Welding rods
- Old camera lens or vintage prescription eyeglasses (look for yellowed or browned optical glass)
- Uranium ores and minerals
- Exempt, unlicensed radioactive calibration sources
- Radium containing clocks, watch hands, compasses, dials, and gauges
- Tritium gunsights and keychain fobs
Check out the site itself for the full story. It's a good read with plenty of information about the history of x-ray photography.