Which of the following is NOT a principle of shadow casting?

The principle of shadow casting in radiography is critical for obtaining clear and accurate images. A large source of radiation does not align with how shadow casting is designed to work effectively. In radiography, the goal is to minimize the size of the x-ray source to produce a sharper image. A smaller radiation source creates less scatter and produces sharper shadows on the film, enhancing clarity and detail.

The correct principles related to shadow casting include parallelism of the subject and the film, which ensures that the rays are evenly projected, and short object-to-film distance, which minimizes the distance that the radiation travels and therefore reduces the potential for distortion. A large source to object distance also helps in reducing the penumbra effect, which can lead to blurring. In summary, a small radiation source is essential for clear image production, making the other principles vital for effective shadow casting while a large source of radiation contradicts this concept.