Preventive Techniques to Reduce Radiation Exposure Questions
Student is required to research issues with employer exposure to radiation and preventive techniques to reduce exposure. Student is required to develop review of 10 important well communicated concepts for radiation safety training and employee exposure reduction.
Introduction to Ionizing
Radiation
Bob Curtis
OSHA Salt Lake Technical Center
Supplement to Lecture Outline
V. 10.02
Basic Model of a Neutral
Atom
• Electrons(-) orbiting nucleus of
protons(+) and neutrons.
• Same number of electrons as
protons; net charge = 0.
• Atomic number (number of
protons) determines element.
• Mass number (protons + neutrons)
gives mass in terms of 1/12th
mass of Carbon atom.
Ionization vs. Excitation
• Excitation transfers enough energy
to an orbital electron to displace it
further away from the nucleus.
• In ionization the electron is
removed, resulting in an ion pair.
– the newly freed electron(-) and the
rest of the atom(+).
Ionizing Radiation
• Any electromagnetic or particulate
radiation capable of producing ion pairs
by interaction with matter.
• Scope limited to X and gamma rays,
alpha particles, beta particles
(electrons), neutrons, and charged
nuclei.
• Important biologically since media can
be altered (e.g., ionized atom in DNA
molecule may be altered, thereby
causing cell death, or mutation).
Particulate vs.
Electromagnetic Radiations
• Particulate Radiations are subatomic particles with mass (e.g.,
alpha and Beta particles, electrons,
neutrons).
• EM Radiations (X-rays and gamma
rays) have no mass and no charge.
Electromagnetic Spectrum
High vs. Low Energy
Radiation
• Absorption of radiation is the process of
transferring the energy of the radiation
to the atoms of the media through
which it is passing.
• Higher energy radiation of the same
type will penetrate further.
• Usually expressed in KeV or MeV
• 1 eV = 1.6 x 10-19 Joules = 1.6 x 10-12
ergs
High vs. Low Linear Energy
Transfer (LET)
• LET is measured by the ionization
density (e.g., ion pairs/cm of tissue)
along the path of the radiation.
• Higher LET causes greater biological
impact and is assigned a higher Quality
Factor(QF).
– Example QF values: X, gamma, and beta
have QF = 1; alpha QF=20; thermal
neutrons QF=3; “fast” neutrons (>10 KeV)
QF = 10; fission fragments QF>20.
Alpha Particles
(or Alpha Radiation)
• Helium nucleus (2 neutrons and 2
protons); +2 charge; heavy (4 AMU).
Typical Energy = 4-8 MeV;
• Limited range (