What is considered "the heart" of radiographic film?

The emulsion is considered "the heart" of radiographic film because it contains the light-sensitive materials that are crucial for the film's function. This layer is composed of silver halide crystals suspended in a gelatin medium. When exposed to radiation or light, these crystals undergo a chemical change that creates a latent image. The development process then transforms this latent image into a visible one by reducing the exposed silver halide, thus forming a detailed representation of the X-ray image.

The emulsion's role is essential in controlling the film's sensitivity, contrast, and overall image quality. Without this critical layer, the film would not be capable of capturing the necessary details. Consequently, the emulsion can be seen as the fundamental component that enables radiographic film to serve its purpose effectively.