Frequently Asked Questions about Radiation

Last updated on December 6th, 2017


I recently came across an FAQ regarding several common questions that people ask about radiation, radiation dose, radiation units of measurement, radiation exposure versus contamination, and radiation treatment drugs. Given the remaining interest surrounding the nuclear accident in Fukushima, Japan, the following information may be of interest to you.

I have excerpted some information which was sourced from the Radiation Emergency Assistance Center/Training Site (REAC/TS) at the Oak Ridge Institute for Science and Education (ORISE), who are recognized around the world for expertise in the medical management of radiation incidents.


What is radiation?

Radiation is energy, in the form of particles or electromagnetic rays, released from radioactive atoms. The three most common types of radiation are alpha particles, beta particles, and gamma rays.


How is radiation measured?

There are two systems of measure used for radiation, the Common System used in the U.S. and the International System used by other countries. The most common units used are rad and rem in the United States and gray and sievert in all other countries.

Conversion Table
1 gray (Gy) ————————– 100 rads
1 milligray (mGy) —————– 100 millirads (mrads)
1 sievert (Sv) ———————–100 rem
1 millisievert (mSv) ————– 100 millirem (mrem)
1 rad ———————————- 10 milligray (mGy)
1 millirad (mrad) —————— 10 micrograys (µGy)
1 rem ——————————— 10 millisieverts (mSv)
1 millirem (mrem) —————- 10 microsieverts (µSv)

Rad and gray are used to describe the amount or “dose” of energy absorbed by a person or animal.

Rem and sievert are used when discussing how much damage that dose of radiation might do to the body.

Different types of radiation affect the body differently, so the same amount, as measured in rads or grays, will have different values in rems and sieverts depending on its source.


What is the difference between radiation exposure and radioactive contamination?

When a person is exposed to radiation, there is no transfer of radioactive material, for example, an x-ray. When a person is contaminated with radioactive material, they take that material with them wherever they go, until they are decontaminated.

Radiation exposure occurs when one is in the presence of radioactive materials.

A person becomes contaminated when they have radioactive material on them or in them. External contamination is on our skin or clothing. Internal contamination is when we breathe in, swallow or otherwise get radioactive materials inside the body.


What about contamination that’s inside my body?

Internal contamination is treated with medications specific to the materials to which you are exposed. Potassium iodide or KI, Prussian Blue, and DTPA are a few of the most common radiation treatment drugs.


What is KI and How does KI work?

KI is a medication that blocks the thyroid gland from absorbing radioactive iodine. It works by providing all the iodine the gland needs so that it doesn’t absorb any of the radioactive iodine. A nuclear power plant accident or nuclear bomb detonation releases radioactive iodine, but KI should only be taken if a significant amount is released.

Potassium Iodide Tablets, 130 mg (14 Tablets)

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