X-ray film is a photographic film that records an image of a body part exposed to X-rays. It's made up of three main parts: a base, an emulsion, and a protective layer: 
Base
A flexible, transparent, and strong support for the emulsion. It's usually made from a clear plastic like cellulose acetate or polyester. 
Emulsion
A layer of gelatin that's sensitive to radiation and forms a latent image on the film. The emulsion is usually coated on both sides of the base to increase the film's speed. 
Protective layer
A thin layer of gelatin that protects the emulsion from cuts during handling
X-ray film is similar to photographic film, but the emulsion is different to account for the unique characteristics of X-rays. X-ray film can be used to create negatives or transparencies. 
X-ray film has been replaced by digital X-rays in many institutions due to technological advancements.