9.1

Dental X-Ray Film Composition and Latent Image

Dental x-ray film serves as a recording medium or image receptor. An image is a picture or likeness of an object, and a receptor is something that responds to a stimulus.

What is the latent image? It is the pattern of stored energy on the exposed film that cannot be seen.

Film Composition

Dental x-ray film has four basic components: the film base, adhesive layer, film emulsion, and protective layer.

In the Iannucci & Howerton, Dental Radiography Principles & Techniques, 6th Edition textbook on page 79, refer to Figure 9-1.

Latent Image Formation

Latent image formation is silver halide crystals that contain various levels of stored energy, depending on the density of the objects in the area exposed. The stored energy forms a pattern known as the latent image and the latent image cannot be seen until chemical processing to produce a visible image.

When photons strike the emulsion, some silver bromide crystals are exposed while others are not. The crystals that are exposed are ionized, and the silver and bromine atoms are separated. Irregularities in the lattice structure of the exposed crystal, as well as sensitivity specks, attract the silver atoms. These aggregates of neutral silver atoms are known as latent image centers.

An example of another type of latent image is fingerprints. If you touch any item, you leave your fingerprints even though you cannot see them on that item. When that item is processed, your fingerprints become visible.

In the Iannucci & Howerton, Dental Radiography Principles & Techniques, 6th Edition textbook on page 80, refer to Figure 9-3.

Media Attributions

• Iannucci & Howerton: Dental Radiography Principles and Techniques, 6th Edition, Chapter 9, CC BY-NC-ND