What is the traditional unit used to measure absorbed dose in tissue?

• A. Roentgen
• B. Rad
• C. rem
• D. Gray

Answer: (B)

The traditional unit used to measure absorbed dose in tissue is the rad. The rad is defined as the amount of radiation energy absorbed per unit mass of tissue, specifically measuring the energy deposited in biological tissues by ionizing radiation. One rad is equivalent to the absorption of 100 ergs of energy per gram of tissue.

Although there are more contemporary units like the Gray, which has become widely accepted in radiological practices and is defined in terms of joules per kilogram, the rad remains significant as a historical unit. Its prevalence in earlier radiological literature and materials has established a long-standing legacy in the field of radiology and radiation oncology.

Other choices, such as the Roentgen, measure exposure in air rather than absorbed dose in tissue, while rem is a unit that accounts for the biological effects of radiation by incorporating a quality factor; it measures dose equivalent rather than absorbed dose.