Primary radiation includes which of the following?

Primary radiation refers specifically to the useful beam of radiation that is emitted directly from the X-ray tube and is intended to produce an image. It is the direct radiation that has not undergone any interaction with matter, such as the patient's body or surrounding equipment.

The useful beam is composed of the radiation that is necessary for diagnostic purposes and is carefully controlled to minimize exposure to surrounding tissues. Understanding primary radiation is crucial for ensuring that the correct amount of radiation is delivered to the imaging area while providing adequate protection for patients and healthcare personnel.

In contrast, scatter radiation and leakage radiation are forms of radiation that do not originate directly from the useful beam. Scatter radiation occurs when primary radiation interacts with matter and changes direction, while leakage radiation refers to radiation that escapes from the X-ray tube housing and is not intended for imaging. Hence, the other options do not accurately represent primary radiation.