In radiographic safety, which statement about dose, shielding, and distance is true?

• A. Dose increases with distance and shielding
• B. Dose decreases with increased distance and shielding; shielding provides barriers to reduce exposure; time should be minimized
• C. Shielding increases dose
• D. Distance has no effect on dose

Answer: (B)

In radiographic safety, dose is managed by three practical actions: increasing distance from the radiation source, using shielding, and minimizing exposure time. The inverse square law means that as you move farther away, the radiation intensity falls off rapidly. For example, doubling the distance reduces the dose to one quarter, and tripling the distance reduces it to one ninth. So greater distance from the tube and patient translates directly to lower exposure.

Shielding works by absorbing or attenuating photons before they reach sensitive tissues. Materials like lead are used because they effectively stop x-rays, and the protective value depends on the material and thickness (often described in terms of half-value layers). Shielding creates physical barriers that reduce exposure for both the operator and bystanders, especially from scatter and leakage radiation.

Minimizing exposure time is another straightforward way to cut dose, since the dose is proportional to how long the exposure lasts. Shorter exposures mean less radiation delivered to any exposed person.

Putting these together aligns with ALARA principles: dose decreases with increased distance and shielding, and time should be minimized. The ideas that dose would increase with shielding or that distance has no effect run counter to these fundamental protections.