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• 1895 - Wilhem Conrad Roentgen discovered X-rays and in 1901 he received the first Nobel Prize for physics.
• 1903 - Marie Curie and Pierre Curie, along with Henri Becquerel were awarded the Nobel Prize in physics for their contributions to understanding radioactivity, including the properties of uranium.
• 1942 - Enrico Fermi and others started the first sustained nuclear chain reaction in a laboratory beneath the University of Chicago football stadium.
• 1945 – Nuclear bombs dropped on Japan.
Historical Awareness
Case Study - Sunburn
Solar radiation wavelengthVisible light – 400 to 760 nm
Ultraviolet radiation (UV) - >400 nm (sunburn)
Infrared radiation - <760 nm (heat)
UV radiationStimulates melanin (dark pigment) that absorbs
UV protecting cells
Health Effects2 to 3 million non-malignant skin cancers
130,000 malignant melanomas
Sunburn – acute cell injury causing inflammatory
response (erythema)
Accelerates aging process
Radium Girls
"Not to worry," their bosses told them. "If
you swallow any radium, it'll make your
cheeks rosy.“
The women at Radium Dial sometimes
painted their teeth and faces and then
turned off the lights for a laugh.
From: 'Radium Girls' By Martha Irvine,
Associated Press, Buffalo News, 1998
Case Study - Radium
1898 – Discovered by Marie Curie
1900-1930 – Radium Therapy - used to treat
arthritis, stomach ailments and cancer
Accepted by American Medical Association
WWI – Use of radium on watch dials
1920s – U.S. Radium corporation employed
young women to paint watch dials
Late 1920s – Radium girls sue, win and
receive compensation
Opium War of 1839-42
Great Britain has a monopoly on the sale of opium which it forces on China. Eventually getting control of Hong Kong.
Consider our societies current “wars on drugs”.
Historical Events
Life & Radiation
• All life is dependent on small
doses of electromagnetic
radiation.
• For example, photosynthesis and
vision use the suns radiation.
Radiation
Nonionizing
Ultraviolet, visible, infrared, microwaves,
radio & TV, power transmission
Ionizing
Radiation capable for producing ions
when interacting with matter – x-rays,
alpha, beta, gamma, cosmic rays
Electromagnetic Spectrum
10-14 10-12 10-10 10-8 10-6 10-4 10-2 1 102 104 106 108
Wavelength in Meters
1010 108 106 104 1021 10-2 10-4 10-6 10-8 10-10 10-12 10-14
Broadcast
Short waveTV
FM
RadarInfrared
Near Far
Visible
UltravioletX Rays
Gamma Rays
Cosmic Rays Power
Transmission
Ionizing Radiation Nonionizing Radiation
Energy - Electron VoltsHigh Low
Nonionizing Radiation
Sources• Ultraviolet light
• Visible light
• Infrared radiation
• Microwaves
• Radio & TV
• Power transmission
Nonionizing Examples
• Ultraviolet – Black light – induce
fluorescence in some materials
• Vision – very small portion that animals
use to process visual information
• Heat – infrared – a little beyond the red
spectrum
• Radio waves – beyond infrared
• Micro waves
• Electrical power transmission – 60
cycles per second with a wave length of
1 to 2 million meters.
Ultraviolet - Sources
• Sun light
• Most harmful UV is absorbed by the
atmosphere – depends on altitude
• Fluorescent lamps
• Electric arc welding
Can damage the eye (cornea)
• Germicidal lamps
• Eye damage from sun light
• Skin cancer
Ultraviolet - Effects
• High ultraviolet – kills bacterial and other
infectious agents
• High dose causes - sun burn – increased
risk of skin cancer
• Pigmentation that results in suntan
• Suntan lotions contain chemicals that
absorb UV radiation
• Reaction in the skin to produce Vitamin D
that prevents rickets
• Strongly absorbed by air – thus the danger
of hole in the atmosphere
Visible Energy
• Energy between 400 and 750 nm
• High energy – bright light produces of
number of adaptive responses
• Standards are set for the intensity of
light in the work place (measured in
candles or lumens)
Infrared Radiation
• Energy between 750 nm to 0.3 cm
• The energy of heat – Heat is the transfer
of energy
• Can damage – cornea, iris, retina and
lens of the eye (glass workers – “glass
blower’s cataract”)
Microwaves & Radio Waves
• Energy between 0.1 cm to 1 kilometer
• Varity of industrial and home uses for
heating and information transfer (radio,
TV, mobile phones)
• Produced by molecular vibration in
solid bodies or crystals
• Health effects – heating, cataracts
• Long-term effects being studied
Electrical Power
• Standard in homes and businesses
• Highest level of exposure from electric-
power generation and distribution
system (high voltage power lines)
• Medical system – Magnetic imaging
• Acute health effects – shock
• Long-term health effects appear to be
few but may some data do suggest
adverse effects
Ionizing Radiation
Ionization Defined
Radiation capable for producing ions
when interacting with matter – in other
words enough energy to remove an
electron from an atom.
Sources – x-rays, radioactive material
produce alpha, beta, and gamma
radiation, cosmic rays from the sun and
space.
Ionizing Radiation
Paper Wood Concrete
Alpha
Beta
Gamma
Energy
Low
Medium
High
Radioactive Material
• Either natural or created in nuclear
reactor or accelerator
• Radioactive material is unstable and
emits energy in order to return to a more
stable state (particles or gamma-rays)
• Half-life – time for radioactive material to
decay by one-half
Alpha Particles
• Two neutrons and two protons Big particle
• Charge of +2
• Emitted from nucleus of radioactive atoms
• Transfer energy in very short distances (10
cm in air) because its big
• Shielded by paper or layer of skin
• Primary hazard from internal exposure ingestion
• Alpha emitters can accumulate in tissue
(bone, kidney, liver, lung, spleen) causing
local damage
Beta Particles
• Small electrically charged particles
similar to electrons
• Charge of -1
• Ejected from nuclei of radioactive atoms
• Emitted with various kinetic energies
• Shielded by wood, body penetration 0.2
to 1.3 cm depending on energy
• Can cause skin burns or be an internal
hazard of ingested
Gamma-rays
• Electromagnetic photons or radiation
(identical to x-rays except for source)
• Emitted from nucleus of radioactive
atoms – spontaneous emission
• Emitted with kinetic energy related to
radioactive source
• Highly penetrating – extensive shielding
required
• Serious external radiation hazard
Gamma-rays
Gamma can be a problem in nuclear wars,
and in using gamma for treatment. In hospitals you need very thick walls in gamma-rooms to stop them from penetrating to outside
Shield is usually made from Lead
There is a massive wall in tel aviv, in case of a
nuclear war, everyone will go inside the walls,
completely isolated from outside.
There can be a psychological problem because
of having so many people in such a small area
for very long.
X-rays
• Overlap with gamma-rays
• Electromagnetic photons or radiation
• Produced from orbiting electrons or free electrons – usually machine produced outside
nucleus
• Produced when electrons strike a target material inside x-ray tube
• Emitted with various energies & wavelengths
• Highly penetrating – extensive shielding required (usually lead, stronger than concrete, so u need a less thick wall)
• External radiation hazard
• Discovered in 1895 by Roentgen
X-rays
• Soft x-ray:
• When a patient takes an X-ray, some particles will reflect from the patient, those reflected radiations have low energy, but they’re still a little harmful, so theses soft X-rays (reflected) can be a hazard to other people around the patient (doctors and nurses)
• Sometimes with an old/very young patient, a person will help the patient to position himself correctly for the X-ray, this person is in danger of soft X-rays, even if they stay away from the primary radiation
Ionizing Radiation Health Effects
We evolved with a certain level of
naturally occurring ionizing
radiation from cosmic radiation,
radioactive materials in the earth.
We have mechanisms to repair
damage. Sometimes the damage may skip the
repair mechanism, so you have a mutation
Radiation Units
Older units:
Curie (Ci): was used to measure
activity of a source, to know if a
source is more active than others
It is the number of disintegrated
atoms per unit time
It does not measure health effects
Radiation Units
Older units:
Roentgen:
Measures ionization power.
when a radioactive material hits a
medium, changing it to the ionized
form, then measure how many ions
are produced
Joul/KG
Doesn’t show health effects.
Radiation Units
Older units:
Rad: (Radiation absorbed dose)
When a radiation hits a body/tissue, it’ll
give it energy, how much of radiation
energy is absorbed into the medium
is rad.
Still, not health effects
Radiation Units
Older units:
REM: Radiation equivalent man (wiki
says its Roentgen equivilent man)
Measures the amount of damage that
occurred in a tissue after it absorbs
energy
Radiation Units
Older units:
There’s a relationship between rad and
rem, they decided that X-ray should
be standard, which means for X-ray
radiation, REM = rad
Means that REM is amount of damage
that occurred in a tissue that
absorbed one rad of X-ray
Radiation UnitsOlder units:
Every radiation has a Coefficient,
called quality factor.
Quality Factor X rad = REM
Example:
If beta was given with the same energy
as an X-ray, it will deal more damage
than the X-ray. Alpha even more
damage. (10 times more Damage;
quality factor = 10)
Radiation UnitsOlder units:
So to know REM from rad, you need to
know the type of radiation and the
quality factor of that radiation.
New Radiation Units
Exposure – X (joul/kg)
(Related to energy)
Absorbed Dose – Gray (Gy)
(amount of energy absorbed) instead of
rad
Equivalent Dose – Sievert (Sv)
(makes different sources of radiation
equivalent) instead of REM
Standards
Occupational Exposure Guidelines
100 mSv over 5 years (average 20 mSv/year)
with a maximum of 50 mSv in any one
year
General public – back ground about 3
mSv/year – Guideline 1 mSv/year
If someone’s exposed to radiation above the
standard exposure, they get a break to
reduce the exposure
Standards
Notice how occupational is 20, general public is 3.
Remember, workers are 20~60 years old, with
usually a better health than the general public.
The general public contains elderly, young
children, sick people ..etc so their exposure
has to be lower
That is why occupational health is different from
public health
Dose Response Tissue
Examples of tissue Sensitivity
Very HighHighest mitotic activity
White blood cells (bone marrow)
Intestinal epithelium
Reproductive cells
High Optic lens epithelium
Esophageal epithelium
Mucous membranes
Medium Brain – Glial cells
Lung, kidney, liver, thyroid,
pancreatic epithelium
Lowlowest mitotic activity
Mature red blood cells
Muscle cells
Mature bone and cartilage
Dose Response Issues
Dose
(Sv)
Effects / organ Time to
death
Death
(%)
1-2 Bone marrow Months 0-10
2-10 Bone marrow Weeks 0-90
10-15Diarrhea,
fever
2
weeks
90-
100
>50 Neurological 1- 4 hrs 100
Dose Response Issues
Notice how its 100% death if it involves the brain. Anywhere else, there’s a possibility that they survive if they’re provided excellent support. Which is expensive
once an accident inside a hospital in france resulted in a few workers getting a rapid very high exposure of radiation, in the hospital, they isolated them completely.
They had to give them huge amounts of blood, up to 500 units of blood. That is unaffordable.
Dose Response Issues
The first 14 days are the most crucial ones, if you survive for the first 14 days there’s a good chance you’ll recover completely..
The doctor read the 2 tables in slides 37, 38, focusing on neurological effects.
The closer you are to the radiation source, the more your dose will be. Meaning those closest so the source of radiation are in the most danger.
• Rate of decay of radioisotope• How long it takes to lose half their
strength
• Can range from very short to billions of years
• Carbon – 5730 years, which makes it valuable for dating (fossils)
Half-life
TimeReduce the spent near the source of radiation.
DistanceIncrease the distance from the source of radiation.
Its actually distance squared, so if you move away 2 meters, you’ll get ¼ of the radiation.
ShieldingPlace shielding material between you and the source of
radiation.
Remember if there’s a nuclear war, its not just about the initial effect, the after-effect is also important, and just as dangerous.
Remember that Bone morrow radiation exposure causes weak immunity
Reducing Exposure
• Occupational exposure guidlines are 100 mSv in 5 years (average, 20 mSv per year) with a limit of 50 mSv in any single year.
• General public the standard is 1 mSv per year. (Natural
background radiation is approximately 3 mSv/year.)
Recommended exposure limits are set by the US National Council on Radiation Protection (NCRP) and world wide by International Council on Radiation Protection (ICRP).
Regulatory Status