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Radiation health effects

Terminology of the health effects of radiation

Becquerel - Curie - Gray - RAD - REM - Roentgen - Sievert


Measurement of radiactivity:

Quantity of any radionuclide in which the number of disintegrations per second is 3.7 x 1010 .

1 Ci = 3.7 x 1010 disintegrations per second (dps)

The International System unit of radioactivity, equal to one disintegration per second.

1 Ci = 3.7 x 1010 Bq

1 Bq = 2.7 x 10-11 Ci

Measurement of absorbed doses and biological damage:

- Old units

Radiation absorbed dose. A unit of energy absorbed from ionizing radiation, equal to 0.01 joules per kilogram of irradiated material.

This unit is not used anymore. It has been replaced as a standard scientific unit by the gray.

The difference between the rad and the gray is a proportionality factor: 100 rads equals one gray

Roentgen Equivalent Man. The amount of ionizing radiation required to produce the same biological effect as one rad of high-penetration x-rays.

This unit is not used anymore. It has been replaced by the sievert. 100 rems equal one sievert.

Amount of x-ray or gamma ray radiation (electromagnetic radiation) that produces 1/3 x 10-9 coulomb of electric charge in one cubic centimeter of dry air at standard conditions.

Although the roentgen describes a different property from energy absorbed per unit mass, the effect of one roentgen on dry air is roughly equal to one rad.

This unit is not used anymore. It has been replaced by the rad and later by the gray.

- Current units

The IS unit for the energy absorbed from ionizing radiation, equal to one joule per kilogram. An
absorbed dose of one gray is equal to the absorption of one joule of radiation energy by one
kilogram of matter.

The gray is the correct unit to use when you wish to monitor energy absorbed per unit mass.

The IS unit for the amount of ionizing radiation required to produce the same biological effect as one rad of high-penetration x-rays, equivalent to a gray for x-rays.

It measures the radioactive dose equivalent.

One sievert is equal to one gray multiplied by a relative biological effective factor, Q, and a factor that takes into account the distribution of the radiation energy, N.

The sievert is the correct unit to use when you wish to monitor the biological danger of radiation.



To choose the Environmental effects per chemical element go to the periodic table of elements

and here to see the definitions and explanations of health effects of chemical elements

and here to see the definitions and explanations of the effects of chemical elements in the environment.

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