Radiation and Its UsesPg. 886-889

Effects of Radiation• Radioactive elements are potentially

hazardous, but the effects are quite subtle• The effects of exposure to radiation may

not be apparent for years!

Effects of Radiation• Radiation damage can be classified in

two groups:• Somatic Damage: damage to the

organism itself, resulting in sickness or death

• Will appear immediately if a massive dose of radiation is received

• Takes years to appear if smaller doses are received, usually in the form of cancer

• Genetic Damage: damage to the genetic machinery of the reproductive cells

• Creates problems that are seen in the offspring of the organism

Effects of Radiation

• Factors that affect the biological effects of radiation:• Energy of the radiation

• The higher the energy of the radiation, the more damage it can cause

• The penetrating ability of the radiation

Effects of Radiation• Factors that affect the biological effects of

radiation:• 1. The ionizing ability of radiation

• Gamma can penetrate deeply, but only causes occasional ionization

• Alpha cannot penetrate as well as gamma, but is very effective in causing ionization, which causes major damage

• 2. The chemical properties of the radiation source

• How long it stays in the body determines how much damage can be done

• Example: Both Kr-85 and Sr-90 decay by beta emission

• Kr-85 is a noble gas and is chemically inert, so it will pass through the body quicker than Sr-90

Let’s figure out how much radiation you are exposed to annually

• Information you will need:• We are 580ft above sea level

• (Salt Lake City, Utah is 4300ft above sea level)

• Nearest nuclear power plants:• Joliet (64 miles away)• Rockford (75miles away)

• Nearest Coal-fired power plant• Waukegan (18miles away)

Effects of Short-Term Exposures to Radiation

Rem indicates the danger the radiation poses for humans.

Dose (rem)

0-25

25-50

100-200

500

Clinical Effect

Nondetectable

Temporary decrease in white blood cell counts

Strong decrease in white blood cell counts

Death of half the exposed population w/in 30 days

Uses of Radiation1. Smoke detectors

2. Neutron Activation

3. Radioactive tracers

4. Cancer Treatment

Why is my smoke detector radioactive?

No smoke Smoke present

Using Radiation• Neutron Activation:

• Sample of interest is hit with neutrons from a radioactive source

• Causes some atoms to become radioactive• Half-life and type of radiation emitted is measured by a computer

• Each atom has specific characteristics

• Can determine elements in original sample

• Used for:• Detection of art forgeries• Gunpowder residue analysis

R C OH

O

R' OH18

+ R C O

O

R'18

+ H O H

R C OH

O

R' OH18

+ R C O

O

R' + H O H18

R C OH

O

H OR'+ R C O

O

R' + H O HH+

Ways to use Radioactive tracers : #1. Learning reaction pathways

Ways to use Radioactive tracers :

#2. Reading DNA

Ways to use Radioactive tracers :

#3. Material Flow

PET and brain activity.

normal Alzheimer’s

asymmetric scan indicates disease

normal

Ways to use Radioactive tracers : #4. Medical Diagnosis

•Other examples:

•Technetium-99m used to detect brain tumors and liver problems

•Phosphorus-32 used to detect skin cancer

•Patient drinks a sample with a small amount of radioactive iodine – 131

•Thyroid uses iodine to make thyroxine

•After two hours, uptake of iodine is measured by scanning with a radiation detector

Using Radiation to Help Us• Cancer Treatment

• Beams of gamma radiation are targeted at the growing tumor

• Can kill healthy cells along with cancerous cells

• However, healthy cells resist treatment more than cancer cells

• Cancerous cells in the middle of the tumor may be immune to the gamma radiation

• Common isotopes used:• Cobalt-60 and Cesium-137

Using Radiation• Cancer Treatment continued:

• Salts of radioisotopes can also be used• Sealed in gold tubes• Implanted into the tumor• Emit beta and gamma radiation• Sealed container prevents them from traveling

throughout the body

Proton Therapy:

http://www.proton-therapy.org/index.html

http://www.niu.edu/protontherapy/index.shtml