What is the term for the part of the X-ray beam that has passed through the patient and reaches the film?

The term used for the part of the X-ray beam that has passed through the patient and reaches the film is remnant radiation. This radiation is crucial because it is the remaining radiation that has interacted with the tissues of the patient and is capable of producing the image on the film or detector.

As the X-ray beam passes through the body, it is attenuated, meaning that some of the radiation is absorbed or scattered by the tissues, while the remnant radiation is what eventually contributes to the image formation. The quality and amount of this radiation affect the visibility of structures in the image, making it a key concept in radiography.

In contrast, primary radiation refers to the initial X-ray beam emitted from the X-ray tube before it encounters any matter. Secondary radiation is generated when primary radiation interacts with matter, resulting in rays that have different energy levels and characteristics than the original beam. Scatter radiation is a specific type of secondary radiation that occurs when X-rays bounce off tissues and change direction, contributing to noise in the image. These terms describe different aspects of radiation behavior but do not refer specifically to the radiation that reaches the film after passing through a patient.