Download Using Radiation

Radiation and Its Uses
Pg. 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)
Clinical Effect
0-25
Nondetectable
25-50
Temporary decrease in white
blood cell counts
100-200
500
Strong decrease in white blood
cell counts
Death of half the exposed
population w/in 30 days
Uses of Radiation
1.
2.
3.
4.
Smoke detectors
Neutron Activation
Radioactive tracers
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
Ways to use Radioactive tracers :
#1. Learning reaction pathways
O
R C OH +
O
+
H OR'
H
R
C O R' + H O H
O
O
18
R C OH + R'
OH
O
O
18
R C OH + R'
18
R C O R' + H O H
18
OH
R C O R' + H O H
Ways to use Radioactive tracers :
#2. Reading DNA
Ways to use Radioactive tracers :
#3. Material Flow
Ways to use Radioactive tracers :
#4. Medical Diagnosis
asymmetric scan
indicates disease
•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
normal
PET and brain activity.
•Other examples:
•Technetium-99m used
to detect brain tumors
and liver problems
•Phosphorus-32 used
to detect skin cancer
normal
Alzheimer’s
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