Transcript IONIZING RADIATION - Indiana University of Pennsylvania

IONIZING RADIATION
….. a discussion of the health hazards
associated with handling and use of
materials capable of producing
ionization of matter.
Some basics of atomic theory…..
• Protons - Atomic particle found in an atom’s nucleus possessing
a positive charge of +1
• Electrons – Atomic particle possessing a negative charge (-1)
• Neutrons – Atomic particle w/ no electric charge
• Atomic weight – Sum of protons and neutrons in the nucleus of
an atom
• Atomic number – The number of protons in the nucleus of an
atom
• Isotopes – Nuclei of an element differing in atomic weight but
having the same atomic number (e.g., U-235 vs U-238)
• Radioactivity – The emission of energy in the form of alpha-,
beta-, or gamma-radiation from then nucleus of an atom
Radiation…
• Radiation has no
unique biological
effects.
• Concept of “half-life”
– Time it takes for a
radioisotope to lose
half its strength
Where is data gathered?
• Early radiation workers
• Medical personnel who routinely administer radiation for
diagnosis or therapy
• Patients treated with radiation
• Workers who painted dials with luminous paints containing
radium
• Japanese atomic bomb survivors
Where does it come from?
• Natural, non man-made radiation accounts for
more than half of the exposure we receive
(rays from sun and stars, earthen materials, in
food, etc.).
• The biggest man-made contribution to
radiation exposure of individuals results from
the medical and dental use of x-rays and of
radioactive materials to diagnose and treat
disease.
Ionizing vs Non-Ionizing
• Ionizing radiation *
– Radiation capable of producing ions
– Comes from x-ray machines, nuclear reactors, and
radioactive materials
• Non-Ionizing radiation
– Comes from microwaves, sound waves, light, lasers,
radiofrequency, electromagnetic fields, etc.
Forms of Ionizing Radiation
• ALPHA
–
–
–
–
Travel only a short distance in air (~ 4” in air)
Stopped by dead skin, film of water, sheet of paper
Very hazardous when taken into the body
Avoid inhalation or ingestion
• BETA
– Penetrate human body to depth of 0.1-o.5”
– Can penetrate wood to about 1.5”
– Stopped by 0.5” aluminum or Plexiglas
Forms of Ionizing Radiation (cont.)
• GAMMA
– Deep penetrating
– Need steel, lead, etc. to shield
• X –Radiation
– Commonly thought of as electromagnetic radiation
produced by an x-ray machine
– Penetration depends on wavelength and material being
irradiated.
– Often use concrete to shield
Penetrating Abilities
• ALPHA - very limited
ability; short range in
air, stopped by skin
• BETA - function of
originating energy;
can penetrate skin
• GAMMA - highly
penetrating; can reach
all body organs
Specific Ionization
• ALPHA - large
particle and short
range --> high S.I.
• BETA - lower S.I.
• GAMMA - the lowest
S.I. (ionization is a
“secondary process”
through electrons
What occupations are at risk?
• Healthcare/Medicine
– Oncology
– Radiation therapy
– Dentistry
• Researchers
• Miners
– Uranium, phosphate, etc.
• Nuclear power plant
employees
Symptoms of Exposure
• High level doses of radiation (generally doses of
more than 100 rads), if received all at once, cause
short-term effects that appear within hours, days,
or weeks. Known as acute radiation syndrome
– Initial symptoms: nausea, vomiting, and malaise.
– After latent period: infections, fever, hemorrhage, loss
of hair, diarrhea, loss of body fluid, CNS effects
– >600 rads leads to death
• Low level doses – risk is proportional to dose, but
disagreement or uncertainty about exact responses.
Adverse Effects
•
•
•
•
•
Cancer
Birth defects
Cataracts
Shortening of lifespan
If reproductive organs
irradiated:
– Genetic mutations may
occur in sperm or egg
cells
Damage from Radiation
• When radiation strikes a cell
– It may pass through the cell without doing any
damage
– It may damage the cell, but the cell partially
repairs the damage
– It may damage the cell so that the cell not only
fails to repair itself but reproduces in damaged
form over a period of years
– It may kill the cell
Factors Determining Damage
• Amount of radiation absorbed/penetrating
ability
• Amount of body area exposed
• Energy of the radiation
• Specific ionization associated with the
radiation (how it damages/what it targets)
Significant Considerations
• If the radioactive source is outside the body,
control strategies include 1) distance, 2)
time, and 3) shielding.
• If the radioactive source is inside the body,
hazard is function of radiation type, energy,
half-lives, radiosensitivity of tissues, etc.,
and control strategies must include all we
know about controlling hazards.
True or False?
• Man-made sources of
radiation, such as
atomic weapons and
x-rays have caused
new diseases never
encountered by
medical science.
True or False?
• You can reduce the
amount of radiation to
which you are
naturally exposed by
living in a house made
of brick, rather than
wood.