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Chapter 18
Key Concepts
53
Health Care
Undergraduate 3
09/26/2014

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Term
what is ionizing radiation?
Definition
radiation that has sufficient energy to produce ions
Term
what does ionizing radiation cause?
Definition
damage that can be repaired, damage that may be permanent, damage that can cause cell death
Term
what are the 2 types of ionizing radiatinon?
Definition
man-made, and environmental
Term
what are examples of natural environmental radiation
Definition
cosmic(sun and stars), earth(uranium, radium, thorium), and radioactive substances(radiopotassium and radiocarbon)
Term
How much radiation do we get from the environment (background radiation)
Definition
more than half
Term
what are the sources of human-made radiation?
Definition
nuclear weapons fall out, medical and dental exposures(90%), industrial radioactive materials
Term
what is the erythema dose
Definition
an old unit of x-ray measurement, measuring the amount of radiation required to turn the skin red
Term
roentgen(C/kg)
Definition
the amount of ionizing radiation that produces ions that carry 1 electrostatic unit of quantity or either positive or negative charge (in 1 cubic centimeter of air)
Term
radiation absorbed dose (rad)(Gy)
Definition
the amount of radiation absorbed by a medium
Term
rem (dose equivalent)(sievert)
Definition
measures the biologic affect of ionizing radiation on humans
Term
effective dose equivalent (EDE)
Definition
the absorbed dose multiplied by the appropriate quality factor and measured in rems)
Term
EDE limits for rad techs
Definition
5 rems per year
Term
EDE limits on students under 18
Definition
.1 rem per year
Term
EDE for pregnant women
Definition
.5 rem total and .05 rem per month
Term
what is an atom
Definition
the smallest part of an element made up of a nucleus and surrounded by electrons
Term
what is a photon?
Definition
packets of energy that have the ability to know electrons out of their orbit
Term
when ionization results in a transfer of energy:
Definition
the x-ray photons can be absorbed, scattered, or pass through without any interaction
Term
what are the 3 main types of photon interactions?
Definition
photoelectric effect, compton scatter, pair production
Term
what is photoelectric effect?
Definition
photon knock an inner orbiting electron out and transfers all it's energy to that electron (usually occurs with low energy photons)
Term
what is compton scatter
Definition
deflects off an orbiting electron (the compton electron) shooting off in a different direction with lower energy (called a scatter photon)
Term
what is pair production?
Definition
a photon with extremely high energy gets close to the nucleus and a positron and electron are formed and once they interact with an orbiting electron they shoot off in different directions (annihilation reaction)
Term
what are the 4 effects that radiation can have on cells
Definition
pass through, repairable damage, irreparable damage, or cell death
Term
the law of bergonie and tribondeau
Definition
cells are most sensitive to the effects of ionizing radiation when they are rapidly dividing
Term
what are the most radiosensitive cells
Definition
lymphocytes along with the eyes, ovaries, and testes (nerve cells are the least sensitive)
Term
what is acute radiation syndrome (ARS)
Definition
when a larger than 100 R dose is received by the entire body over a short time
Term
what are the 2 categories of long term biologic effect?
Definition
somatic and genetic
Term
what are the 2 categories of long term biologic effect?
Definition
somatic and genetic
Term
what are somatic effects?
Definition
effect that occur in general body cells and involve all functions (except reproduction) and include cancer, cataracts, and life-span shortening
Term
examples of somatic effects
Definition
birth defects, mental retardation, childhood leukemia, skeletal and CNS abnormalities,
Term
types of cancer caused by radiation
Definition
bone sarcomas (watch painters), skin carcinomas (radiologists and techs), and lung cancer (uranium mines workers), cataracts (A-bomb survivors)
Term
what are genetic effects
Definition
occur in the germ cell and are passed down to future generations.
Term
what are the 2 sources of medical radiation exposure
Definition
x-rays (external), and radionuclides (internal)
Term
how are x-rays formed?
Definition
a high voltage accelerates the electrons toward a metal target
Term
what does kilovoltage control?
Definition
the quality of the x-ray beam
Term
what does milliampere control?
Definition
quantity or the amount of radiation produced
Term
what is primary radiation?
Definition
the x-rays produced by the tube before it hits any matter
Term
what is secondary radiation?
Definition
when the primary radiation interacts with matter
Term
what is scatter radiation?
Definition
harmful to the patient and impairs the diagnostic image
Term
what are radionuclides used for?
Definition
the treatment of patients with cancer (radiation therapy or oncology)
Term
what is cobalt 60?
Definition
a human made radionuclide
Term
what is radioactive half-life?
Definition
the time needed for the disintegration of one half of the atoms of the nuclide
Term
what are good housekeeping practices for internal radiation?
Definition
not eating, smoking, or food prep/storage in areas where radionuclides are present
Term
what is optimal kilovoltage?
Definition
As high as possible because it decreases skin dose
Term
what is the inverse square law
Definition
the intensity of the beam is inversely proportional to the square of the distance
Term
inverse square law correlations
Definition
when distance is doubled, there is 1/4 the radiation exposure and when the distance is halved, the exposure rate is quadrupled
Term
minimum filtration used in an x-ray tube
Definition
2.5 mm of aluminum
Term
collimation
Definition
limits the area of exposure to the patient
Term
what is the reduction in exposure when gonad shielding is used?
Definition
95%
Term
how much lead should be present in shielding devices?
Definition
.25 mm of lead (.5 mm is suggested for flouro)
Term
3 types of gonadal shielding
Definition
shadow shields, flat contact shields, and the shaped contact shield (used by men)
Term
3 types of gonadal shielding
Definition
shadow shields, flat contact shields, and the shaped contact shield (used by men)
Term
OSL
Definition
optically stimulated luminescent dosimeter, worn at the neck to measure dose to the eyes
Term
TLD
Definition
thermoluminescent dosimetry (highly accurate)
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