SOURCES OF IONIZING RADIATION

Divided into 2 main categories:
1.
Natural environmental radiation

2.
Annual dose of approx. 3 mSv
Man-made radiation
 Results in 3.2 mSv anually

Millisieverts (mSv)

the unit of effective dose

Use to express radiation exposure of populations and radiation risk
in those populations.

Natural Environmental Radiation
 Consist of four components:
1. Cosmic rays

are particulate and electromagnetic radiation emitted the sun
and stars.

On Earth, the intensity of cosmic radiation increases with
altitude and latitude.
2. Terrestrial radiation
 results from deposits of uranium, thorium, and other
radionuclides in the Earth.
 The intensity is highly dependent on the geology of the local
area.
3. Internally deposited radionuclides

mainly potassium-40 (40K), are natural metabolites.

always been with us and contribute an equal dose for each of
us.
4. Radon


largest source of natural environmental radiation
a radioactive gas that is produced by the natural radioactive
decay of uranium, which is present in trace quantities in the
Earth.

all Earth-based materials, such as concrete, bricks, and gypsum
wall-board contain radon.

emits alpha particles, which are not penetrating, and therefore
contributes a radiation dose only to the lung.

Man-made Radiation

Diagnostic x-rays constitute the largest man-made source of ionizing
radiation.

(3.2 mSv/yr) estimated in 2006 by the National Council in Radiation
Protection and Measurements (NCRP).
- currently accepted approximate annual dose resulting from
medical applications of ionizing raditaion.

(0.4 mSv/yr) early estimation in 1990 by the NCRP.
- the increased during this 16-year period is principally attributable
to the increasing use of computed tomograph (CT) and high level
fluoroscopy.

Other sources of man-made radiation:
1.
Nuclear power generation

Nuclear power stations and other industrial applications
contribute very little to our radiation dose.
2.
Research applications
3.
Industrial sources
4.
Consumer items/products

Such as watch dials, exit signs, smoke detectors, camping
lantern mantles and airport surveillance systems contribute
0.1 mSv to our annual radiation dose.