DANB Radiation Health and Safety (RHS) Practice Exam

Increasing the target film distance primarily serves to:

1. Increase scatter radiation

2. Reduce film speed

3. Decrease radiation intensity

4. All of the above

The correct answer is: Decrease radiation intensity

Increasing the target film distance primarily serves to decrease radiation intensity. When the distance between the radiation source (the target) and the film increases, the intensity of the radiation that reaches the film decreases according to the inverse square law. This law states that the intensity of radiation is inversely proportional to the square of the distance from the source. Therefore, as the distance doubles, the intensity is reduced to one-fourth of its original value. This principle is crucial in radiography and radiation safety, as it helps in minimizing the dose of radiation the patient and the film are exposed to. While increasing the distance can have effects on scatter radiation and film speed, the primary and most direct result related to radiation intensity is the decrease caused by the increased distance.