How many times must the primary beam scatter before reaching the radiographer behind the control booth?

The correct number of times the primary beam must scatter before reaching the radiographer behind the control booth is two. This is based on the principles of radiation safety and protection in radiography.

When the primary beam enters a patient, it does not travel directly to the radiographer; instead, it interacts with the body's tissues, leading to scattering. The primary beam scatters upon interaction with the patient, and it is this scattered radiation that can potentially reach the radiographer. The first scatter occurs when the beam hits the patient, and then it scatters again before reaching the control booth. These interactions dilute the intensity of the radiation and direct it in various directions.

This understanding is crucial for ensuring the safety of radiographers by emphasizing the need for shielding and protective barriers, particularly in areas where scatter radiation is prevalent. Proper knowledge of how many times the beam scatters helps in designing safe work environments and implementing protocols that reduce exposure.