instant film x-rays
Taking x-ray photographs with instant film (Polaroid and Fuji)
consumer grade instant film
Old Polaroid instant film was sensitive to x-rays for 10 seconds or so after the development process was started. This enabled one to eject a single picture and then quickly expose it to x-rays to produce a good image. Polaroid is no longer available, unfortunately. I have attempted this technique using Fuji Instax film, but this film is only sensitive to x-rays for 1 or 2 seconds once the development process has started, and even then the images are very weak. This process seems useless with Fuji Instax.
professional peel-apart instant film
Fuji FP-100BS and Fuji FP-100C are useful for x-ray photography.
Color film works quite well. The results differ in terms of contrast and detail versus black and white film, so both films are useful.
x-ray burned images (solarized)
The color pigments are sensitive to excessive ionization. Long x-ray exposure will destroy pigments and will cause "solarized" effects. In fact, very long exposures can actually result in negative images. This property of color pigments can create pleasing effects, but it can also have practical applications. First, this burned technique can capture much finer details. The scintillation screen is not necessary, so one source of scattering and diffusion is eliminated. Second, the setup and processing steps turn out to be much simpler. You don't need to use any dark-room techniques! You can remove an unexposed film in full light; expose the film to x-rays in full light; then pull the film through a developer roller in full light.
The downside is that you need to use fairly long exposures with this technique. Whereas an exposure using an image intensifier scintillation screen might require a 1/2 second exposure, the burn technique might require a 5 to 10 second exposure.
black and white film
Black and white instant film seems resistant to x-ray burn (solarizing). The contrast behavior is also different.