Radiation Safety Practice Exam

What is the primary unit used to express the dose of radiation absorbed by human tissue?

1. Electron volt

2. Roentgen

3. RAD

4. Sievert

The correct answer is: RAD

The primary unit used to express the dose of radiation absorbed by human tissue is the RAD, which stands for "Radiation Absorbed Dose." This unit is specifically designed to quantify the amount of energy deposited by ionizing radiation in a given mass of tissue. One RAD is equal to an absorbed dose of 0.01 gray, where the gray is another unit of absorbed dose. The RAD is important in the context of radiation safety because it directly relates to the potential biological effect of radiation on tissues and organs. While other units like the roentgen and electron volt are used in radiation measurement, they do not directly measure the absorbed dose in human tissue. The roentgen is primarily a measure of exposure to X-rays and gamma rays in air, while the electron volt is a unit of energy rather than a measure of dose. The Sievert is also important as it factors in biological effect and is commonly used in assessing the impact of radiation on human health, but it is based on the dose in gray, making the RAD more directly associated with absorbed dose measurements.