What does RAD stand for?

• A. Radioactive Dose
• B. Radiation Absorbed Dose
• C. Radionuclide Activity
• D. Radioisotope Dose

Answer: (A)

RAD stands for Radiation Absorbed Dose. It’s the amount of energy from ionizing radiation deposited in a unit mass of material, typically tissue. This quantity is about energy per mass, not about how much radioactivity is present or how quickly it decays. The energy deposited is measured in joules per kilogram, and the rad is an older unit where 1 rad equals 0.01 gray (Gy). That means 100 rad equals 1 Gy.

Some answer choices mix up related ideas: “Radioactive Dose” isn’t a standard term, and radionuclide activity describes how fast a substance decays (decays per second, like becquerels or curies), not the energy actually absorbed. The concept of RAD is distinct from dose equivalents (rem or sievert), which adjust absorbed dose for biological effects.