Which of the following is NOT a common measurement unit for radiation exposure?

The unit that is recognized as NOT a common measurement for radiation exposure is the calorie. In the field of radiation protection and dosimetry, specific units are used to quantify different aspects of radiation.

The sievert is a unit that measures the biological effect of ionizing radiation, reflecting the risk of health effects from exposure. It takes into account the type of radiation and its effectiveness in causing biological damage.

The gray measures the absorbed dose of radiation, indicating the amount of energy deposited in a material (or tissue) by ionizing radiation.

Roentgen is a unit used to measure exposure to gamma and X-rays, representing the amount of ionization produced in air by radiation.

In contrast, the calorie is a unit of energy commonly used in nutrition and does not pertain directly to radiation exposure or its biological effects. Its association with energy rather than ionizing radiation makes it the outlier among the other options provided.