Contact Dose Rates are typically measured how?

• A. At 1 meter away from the source
• B. In contact or as close to the source as possible
• C. At 30 centimeters from the source
• D. In the surrounding area at several meters

Answer: (B)

Contact dose rate is the radiation dose rate measured directly at the surface of the source or right up against it. This captures the maximum exposure a person would face when handling or inspecting the source, since radiation intensity is highest at zero distance and falls off with distance (inverse-square behavior) and with any shielding. Measuring in contact or as close as possible provides the strongest, worst‑case value needed to characterize the source and plan safe handling, shielding, and work procedures. Distances like 30 cm, 1 meter, or several meters are used for assessing doses at those gaps, but they do not reflect the highest possible exposure, which is why the measurement is taken in contact.