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when x-rays strike pt tissues ______ results
ionization
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true or false. All ionizing is harmful, and biological change from dental x-radiation is small, byt does still have biologic damage
both statements are true
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Ionization of water results in the production of hydrogen and hydroxyl _____ _______
free radicals
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suggests that cell damage results when ionizing radiation directly hits critical areas, or targets within the cell (DNA)
direct theory
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suggests that x-ray photons are absorbed within the cell and cause the formation of toxins, which in turn damage the cell
indirect theory
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When dose and damage of radiation are plotted on a graph, what type of relationship is seen?
linear, nonthreshold
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true or false. there is NO safe amount of radiation, in dental radiation, damage always does occur
true
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effects that occur as a direct function of dose; the probability of occurence increases with dose, but the severity of effects does not depend on the magnitude of the absorbed dose; they do not have a dose threshold
stochastic effects
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cancer induction and genetic mutations are what type of effects?
stochastic
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effects that have a threshold and increase in severity with increasing absorbed dose
nonstochastic
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erythema, loss of hair, cataract formation, and decreased fertility are examples of what effect?
nonstochastic
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Why do high dose rates cause more damage?
because the tissues don't have enough time to repair themselves
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result from exposure to a nuclear accident or atomic bomb - associated with large amounts of radiation in small amounts of time
short-term effects
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effects that appear after years and years, associated with small amounts of radiation absorbed repeatedly over a long period of time - linked to the induction of cancer, birth abnormalities, and genetic defects
long term effects
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All cells in the body except the reproductive cells
somatic cells
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reproductive cells
genetic cells
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effects seen in the person irradiated and not transmitted to future generations
somatic effects
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effects not seen in the person irradiated, but passed to future generations
genetic effects
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What are radiosensitive cells?
- blood cells
- immature bone cells
- young bone cells
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What cell is most sensitive to radiation?
small lymphocyte (blood cells)
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what are radioresistant cells?
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What are radiosensitive organs?
- lymphoid tissue
- bone marrow
- testes
- intestines
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What are radioresistant tissues?
- salivary glands
- kidney
- liver
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Critical organs in dental radiography include:
- skin
- thyroid gland
- lens of eye
- bone marrow
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a way of measuring radiation exposure by the amount of ionization that occurs in air
Roentgen
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The amount of energy absorbed by a tissue; how is it measured?
- Dose
- rad (radiation absorbed dose)
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How much radiation reduction do you get from using f-speed film?
60%
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A longer source to flim distance will _______ pts exposure to radiation
decrease
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true or false. The Roentgen (R) measures the amount of energy that reaches the surface of an organism, and the amount of radiation absorbed
FALSE! It does NOT measure the amount of radiation absorbed!
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SI unit that measures the number of electrical charges, or ion pairs in 1 kg of air
coulomb/kg
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What measurement is used to compare the biological effects of different types of radiation?
dose equivalent
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the product absorbed dose (in rads) and quality factor specific for the type of radiation; the traditional unit of the dose equivalent
Rem - roentgen equivalent in man
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a _____ _______ or dimensionless multiplier is used to place the exposure effects of different types of radiation on a common scale
Quality factor
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SI unit equivalent of the rem is __________
sievert (sv)
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SI unit equivalent of the rad is ________
gray (gy)
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a form of ionizing radiation that is ubiquitous in the environment, and which humans are exposed to daily
background radiation
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Radiation that originates from the stars and the sun, and the higher the elevation, the more of this you recieve
cosmic radiation
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radiation that is emitted from radioactive materials present in the earth and air including potassium and uranium
terrestrial radiation
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What type of radiation is the single largest contributor to artificial radiation?
medical radiation
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true or false. Risk estimates suggest that death is more likely to occur from common activities than from the dental radiographic procedures, and that cancer is far more likely to be unrelated to radiation exposure
true
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The use of a rectangular collimator reduces absorbed radiation dose by ______ %
60-70 %
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