Which factor is not considered in determining subject contrast?

The factor that is not considered in determining subject contrast is the type of film used. In radiographic testing, subject contrast refers to the difference in radiographic density between various materials in the radiographic image as influenced by their thickness, density, and atomic number. While the type of film can influence overall image quality and sensitivity, it does not directly affect the inherent contrast of the subject being imaged.

Subject contrast is primarily influenced by the characteristics of the radiation used (such as energy and penetration capability), the distance from the source to the film, and exposure parameters like tube voltage and exposure time. These factors can change how much radiation interacts with the subject and the resulting image, thus affecting how well the desired features are visualized.

The source-to-film distance impacts the intensity of the radiation that reaches the film, thereby affecting image contrast. The tube voltage influences the quality of the radiation, determining its ability to penetrate materials of different densities, and exposure time plays a role in the overall density that is recorded on the film. However, the specific type of film does not contribute to the subject contrast itself in the same direct manner as these other factors.