3. Natural Background Radiation

NBR stand for

Natural Background Radiation

What are the 3 sources of Natural Background Radiation?

1. Cosmic

2. Terrestrial

3. Internal

What entities (typically sub-atomic particles) constitute cosmic rays?

NM EM PPP

1. Neutrons

2. Muons

3. Electrons

4. Photons

5. Protons

6. Pions

The exposure from cosmic rays varies with what?

1. Solar sunspot cycles

2. Latitude 

3. Altitude 

T/F cosmic ray exposure is higher at the equator than at the polar regions.

False, other way around

T/F: Cosmic ray exposure increases with increasing altitude

True

Cosmic ray exposure increases with increasing altitude by:

doubles per 2000 meter

Name 4 isotopes that constitute terrestrial radiation 

1. Uranium 

2. Thorium 

3. Radium 

4. Radon 

UT RR

What tissue does Rn gas damage the most?

Lung

What is the 2nd leading cause of lung cancer in the US?

Radon exposure

What is internal radiation?

Radioactive materials that are normally present in our bodies

Name 4 sources of interal radiation 

SH C3P0

1. Strontium 90

2. Hydrogen 3

3. Carbon 14

4. Potassium 40

Which of the 4 sources produces the highest doses to the body?

Potassium-40

Effective Dose Equivalent (avg. NBR dose per year) from all sources except radon

100 mR/ year 

or 0.1 REM | 10 mSv

Effective Dose Equivalent for radon(avg)

200 mR/ year

T/F: The Effective Dose Equivalent of NBR varies greatly by source.

True

Cosmic radiation aka

Solar wind

Cosmic radiation consists primarily of

photons

Most cosmic radiation is blocked/ reflected by___

the atmosphere 

What is the most important type of cosmic radiation?

UV radiation

Which of the following cities might have the highest level of cosmic radiation?

1. San Francisco

2. Miami

3. Houston

4. Albuquerque

4. Albuquerque, cuz it has the highest elevation

Rule of thumb: If a city is on the coast, it is low elevation

Man made radiation exposure total average

98 mR = 0.98 mSv

Round it up to 100 mR

TLDR for exposures

1. NBR (excluding radon)

2. Man made radiation

3. Radon gas

Total avg of natural background radiation & man-made radiation (not including radon)

2 mSv (200 mR)

Where does the radiation come from? Give examples.

1. Cosmic

2. Terrestrial

3. Internal

1. Cosmic: the sun & outer space. Most important one: UV radiation

2. Terrestrial: seeps up from the Earth’s crust. e.g. Radon Gas

3. Internal: naturally produced in our own bodies. Most common: Potassium 40

What is another exposure source aside from NBR and the man-made radiations discussed in class?

Tobacco products

Smokers receive an effective dose equivalent of

1300mR

T/F: In addition to natural background radiation, dose increases to the population at large with use of medical x-rays

True

% of the population that has an x-ray each year

65%

Average annual dose from medical use

20 mR/ year = .2 mSv/ year

GSDe stands for

Genetically Significant Dose Equivalent

GSDe aka

Public at large

What is GSDe?

A weighted avg. gonadal dose that takes into account persons who are irradiated vs those that are not and averages the result

GSD for USA is ~

1.3 mSv = 130 mR