Radiation Protection
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| What is the formula for the inverse square law? | I1/I2=D2(squared)/D1(spuared).
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| Late or Long term effects of radiation exposure are | Linear Nonthreshold ("all or nothing").
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| Nonstochastic effects | are those that will not occur below a particular threshold dose and that increase in severity as the dose increases.
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| According to the NCRP, the annual occupational whole-body dose equivalent limit is | 50 mSv (5 rem or 5000 mrem).
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| The annual occupational whole-body dose equivalent limit for students under the age of 18 years is | 1 mSv (100 mrem or 0.1 rem).
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| The annual occupational dose equivalent limit for the lens of the eye | is 150 mSv (15 rem or 15,000 mrem).
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| The annual occupational dose equivalent limit for the skin and extremities | is 500 mSv (50 rem or 50,000 mrem).
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| The total gestational dose equivalent limit for embryo/fetus of a pregnant radiographer | is 5 mSv (0.5 rem or 500 mrem).
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| Photoelectric Effect | a relatively low-energy incident photon uses all of its energy to eject an inner-shell electron, leaving a vacancy. An electron from the next shell will drop to fill the vacancy, and a characteristic ray is given up in the transition.
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| Compton scatter | highenergy incident photon ejects outershell elec. incident photon is dflctd w/reduced ener but usual keeps most of its energy & exits body as energetic sctrd ray. Sctrd ray will ethr help 2 image fog or pose a rad hazard 2 techs, dpndng on drctn of exit
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| Classical Scatter | a low-energy photon interacts with an atom but causes no ionization; the incident photon disappears into the atom, and is then immediately released as a photon of identical energy but changed direction.
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| Thompson Scatter | is another name for classical scatter
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| The x-ray interaction with matter that is responsible for the majority of scattered radiation reaching the IR is | Compton Scatter
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| The following formula is used to determine Effective Dose (E): | Effective Dose (E) = Radiation Weighting Factor (Wr) × Tissue Weighting Factor (Wt) × Absorbed Dose
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| The Radiation Weighting Factor (Wr) | is a number assigned to different types of ionizing radiations in order to better determine their effect on tissue (eg, x-ray vs alpha particles).
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| The Tissue Weighting Factor (Wt) | represents the relative tissue radiosensitivity of irradiated material (eg, muscle vs intestinal epithelium vs bone, etc).
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| Inverse Square Law | exposure rate is inversely proportional to the square of the distance; that is, if the SID is doubled, resulting beam intensity will be one 4th the orig intensity; if SID is cut in half, resulting beam intensity will be four times the original intensity.
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| Somatic effects are | those induced in the irradiated body.
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| Genetic Effects are | effects that may not appear for many of years.
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| Isobars are | atoms with the same mass number but different atomic numbers.
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| Isotones | have the same number of neutrons but different atomic numbers.
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| Isomers | have the same atomic number and mass number; they are identical atoms existing at different energy states.
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| Rem (dose-equivalent) is the only unit of measurement that expresses | the dose-effect relationship.
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| In radiation protection, the product of absorbed dose and the correct modifying factor (rad × QF) is used to determine | rem (Sv).
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| Explain Linear Dose-response curve | has no threshold; that is, there is no dose below which radiation is absolutely safe.
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| Explain The nonlinear/sigmoidal dose-response curve | has a threshold and is thought to be generally correct for most somatic effects—such as skin erythema, hematologic depression, and radiation lethality (death).
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| Rad measures | the energy deposited in any material
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| Roentgen is | the unit of exposure; it measures the quantity of ionizations in air.
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| Rem is | an acronym for radiation equivalent man; it includes the RBE specific to the tissue irradiated and therefore is a valid unit of measurement for the dose to biologic tissue.
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| The unit of measurement used to express occupational exposure is the | Rem (Sv)
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| The Curie is | the unit of radioactivity, describing disintegrations per second.
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| Describe X-rays used for Diagnostic purposes: | is of relatively low energy. Kilovoltages of up to 150 are used, as compared with radiations having energies of up to several million volts. X- and gamma radiations, having no mass or charge, are low-LET radiations.
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| Isotpes are | atoms of the same element, with the same Atomic# (# of protons), but different Mass# (# of Neutrons).
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| Radiation-induced malignancy, leukemia, and genetic effects are | late effects (or stochastic effects) of radiation exposure. These can occur years after survival of an acute radiation dose, or after exposure to low levels of radiation over a long period of time.
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| If 600 rad or more is received as a whole-body dose in a short period of time, certain effects will occur; these are referred to as | Acute Radiation Syndrome.
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| Scattering | occurs when there is partial transfer of the proton's energy to matter, as in the Compton effect.
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| Absorption occurs | when an x-ray photon interacts with matter and disappears, as in the photoelectric effect.
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| The reduction in the intensity (quantity) of an x-ray beam, as it passes through matter, is termed | Attenuation
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| Divergence refers | to a directional characteristic of the x-ray beam, as it is emitted from the focal spot
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| Somatic effects of radiation refer to | those effects experienced directly by the exposed individual, such as erythema, epilation, and cataracts.
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| Genetic effects of radiation exposure are caused by | irradiation of the reproductive cells of the exposed individual and are transmitted from one generation to the next.
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| What are some secondary barriers | Secondary barriers protect from secondary (scattered and leakage) radiation. Secondary barriers are control booths, lead aprons, and gloves, and the wall of the x-ray room above 7 feet.
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| Nonstochastic effects are | those that will not occur below a particular threshold dose and that increase in severity as the dose increases.
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| Describe Stochactic Effects | Most late effects do not have a threshold dose; that is, any dose, however small, theoretically can induce an effect. Increasing that dose will increase the likelihood of the occurrence, but will not affect its severity.
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