Radiation absorbed dose (rad)

Definition

Radiation absorbed dose (rad) is a unit of measurement for the amount of energy deposited by ionizing radiation in a substance, typically human tissue. One rad is equivalent to 0.01 joules of energy absorbed per kilogram of tissue.

5 Must Know Facts For Your Next Test

1. 1 rad = 0.01 joules per kilogram.
2. The rad has been largely replaced by the gray (Gy) in the International System of Units (SI), where 1 Gy = 100 rad.
3. Rad measures the energy deposition but does not account for biological effects; for that, units like rem or sievert are used.
4. It is used to quantify the dose received from exposure to ionizing radiation such as X-rays and gamma rays.
5. Understanding rads is crucial for assessing potential damage to living tissues from various types of radiation.

Review Questions

• What is the equivalent of one rad in joules per kilogram?
• Which SI unit has largely replaced the rad, and what is its conversion factor?
• Why might scientists prefer using units like rem or sievert over rad when evaluating biological effects?

Related terms

Gray (Gy): The SI unit for measuring absorbed radiation dose, where 1 Gy equals 1 joule per kilogram.

Sievert (Sv): A unit that accounts for the biological effects of ionizing radiation, with weighting factors applied to different types of radiation.

Ionizing Radiation: Radiation with enough energy to remove tightly bound electrons from atoms, creating ions.