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88 Cards in this Set
- Front
- Back
In dental radiography the term _ is used to describe the mean energy or penetrating ability of the xray beam
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Quality
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Which of the following statements is/are true of wavelengths in reference to radiation?
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X-rays with longer wavelengths have less power AND X-rays with longer wavelengths are more likely to be absorbed by matter
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__ is the the measurement of force that refers to the potential difference between two electrical charges
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Voltage
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When the voltage is increased:
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Electrons move from the cathode to the anode with more speed
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Which of the following is true of the use of voltage in dental xray equipment
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Dental xray equipment requires the use of 65-100 kilovolts
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When contrasted with the use of 65 kV to 75 kV for dental X-rays the use of 85 kV to 100 kV produces
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More penetrating dental X-rays with shorter wavelengths
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The kVp represents
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Max voltage or peak of direct current
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When kilovolt peak is increased
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High energy xray beam with increased penetrating ability
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(1)Density is the overall darkness or blackness of a film. (2)When kVp is increased while other exposure factors remain constant the resultant film appears decreased density with overall lighter. Which are true?
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First statement is true second is false
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When low kilo voltage peak settings are used (65kVp-70kVp) a film with __ will result
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High contrast
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A film with low contrast (greater or equal to 90kVp)
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Useful for detection of periodontal or periapical disease and has many shades of gray
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Exposure time is measured in:
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Impulses
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Aluminum filters;
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Reduce the intensity of the xray beam
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(1)All ionizing radiations are harmful and produce biologic changes in living tissue. (2) the amount of radiation used in dental radiography is small but Biologic damage does occur.
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Both statements are true
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What specific mechanism of radiation injury may result in the formation of hydrogen peroxide when xray energy is absorbed by patient tissues?
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Free radical formation created by the ionizing of water may occur
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Which of the following mechanisms of radiation injury may occur when xray energy is absorbed by patient tissues?
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Ionization and free radical formation
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Which is true regarding the direct theory of radiation injury?
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It involves a direct hit and absorption of an xray photon within a cell
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The indirect theory proposes that:
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Chapter 4 #5
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The quantity is of the xrays produced is controlled by the
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Milliamperage
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Milliamperage regulates the _ of electrons produced at the cathode filament
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Quantity
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Milliampere seconds is a combination of milliamperes and
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Exposure time
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Using 10 mA with an exposure time of 3 seconds would result in 30 mAs. If the milliamperage is increased to 15 the time must be decreased to _ seconds to maintain the same density of the exposed radiograph
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2
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In regard to increasing density
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Increase in either kVp or mA will increase density
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Which of the following changes will increase xray beam intensity?
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Source-to-film distance
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According to the inverse square law, the intensity of radiation is _ proportional to _ from the source of radiation
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Inversely; square of the distance
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According to the inverse square law, if the length if the PID is doubled the resultant beam is _
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PID doubled = one quarter |
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Aluminum filters are used to remove _ energy _ wavelength X-rays.
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Low; longer
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According to the dose response curve when does and damage are plotted on a graph, a __ relationship is seen
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Linear, nonthreshold
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Which of the following is considered a short term effects radiation exposure
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Hair loss
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Ch 4 #17
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Ch4 #17
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A no threshold dose response curve suggests
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No matter how small the amount of radiation received, some biological damage occurs
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Stochastic Biologic effects from radiation:
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Occur as a direct function of dose
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Examples of nonstochastic effects include
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Erythema and loss of hair
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The _ radiation received and the _ the dose rate; the shorter the latent period
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More; faster
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Cellular injuries following the latent period may include (1) cell death (2) cessation mitoric activity and/or (3) abnormal mitoric activity.
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1,2,3
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_ refers to the quantity of radiation received or the total amount of radiation absorbed
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Total dose
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1) More radiation damage takes place with high dose rates (2) because a rapid radiation does not allow time for cellular damage to be required
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Both statements are true
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Which types if cells are more sensitive to radiation; (1) rapidly dividing (2) slowly dividing (3) young (4) old
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1 and 3
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Short term radiation effects are associated with:
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Large amounts of radiation absorbed in a short time and acute radiation syndrome
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Which of the following is considered short-term effect of radiation exposure?
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Hair loss
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__ is/are the single largest contributor to artificial radiation exposure
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Medical radiation
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Which of the following statements is/are true of the average dose of background radiation received by an individual in the United States
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The average dose ranges from 150 to 300 millirads and geographic areas at a higher elevation are associated with increased amounts of cosmic radiation
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The potential risk of dental radiography inducing a fatal cancer in an individual is about __ the risk of a person developing cancer spontaneously.
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1/1,000
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A 1 in 1 million risk of a fatal outcome is associated with the following activities
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All the choices
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Risk estimates suggest (1) that death is more likely to occur from common activities than from dental radiographic procedures and (2) cancer is much more likely to be unrelated to radiation exposure
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Both statements are true
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The use of F-speed film instead of D-speed film reduces the absorbed dose by __%
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60%
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Which of the following modifications in technique will reduce patient exposure to radiation during dental radiographic procedures?
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Longer source-to-film distance
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Which of the following combinations will result in the lowest absorbed dose for the patient from a 20-film series of dental radiographs
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Rectangular collimator with F speed film
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The fundamental unit of matter is:
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Atom
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The nucleus of an atom contains:
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Protons and neutrons
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What is true of somatic effects of irradiation?
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Changes are not transmitted to future generations
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Which subatomic particle carries a negative electrical charge?
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Electron
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Which of the following is true of orbits or the shells in the atom?
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K shell is the closest to the nucleus and has highest energy level
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Which of the following elements is the simplest atom which an atomic number of 1?
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Hydrogen
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The binding energy or binding force of an electron is?
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Weaker for electrons located in outer shells
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What is true of ionization?
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Gains an electron has a negative charge and atom loses and electron and has a positive charge
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An ion pair results when:
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Electron is removed from an atom
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Radiation is the emission and propagation of energy through space or a form of waves and particles (2) radioactivity can be defined as the process by which certain unstable atoms or elements undergo spontaneous disintegration to form a more balanced nuclear state
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Both are true
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Radioactivity is:
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The process by which certain unstable atoms or elements undergo spontaneous disintegration or decay in an effort to become more balanced
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What is true of ionizing radiation?
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Capable of producing ions by removing or adding an electron to an atom AND can be particulate or electromagnetic radiation
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Particulate radiations:
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Tiny particles of matter
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Which of the following types of cells is most radio sensitive?
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Blood
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Cathode rays are derived from which of the following types of particulate radiation?
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Electrons
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Which of the following types of particulate radiation are emitted from the nucleus of radioactive atoms?
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Beta particles
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Electromagnetic radiation
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Has no mass
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Which of the following forms of electromagnetic radiation are capable of ionization?
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X-rays
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Photons are
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Component of particle concept of electromagnetic radiation
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What is true of the wave concept of electromagnetic radiation?
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Frequency and wavelength are inversely related
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Which of the following forms of electromagnetic radiation has the shortest wavelength?
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Dental xray wave
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Which of the following components of the tubehead absorbs heat created by the production of X-rays?
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Insulating oil
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Which component aims and shapes the beam?
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PID
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Within the X-ray tube electrons are generated by the:
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Tungsten filament in the cathode
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Which of the following are considered radioresistant tissues?
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Salivary glands
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Purpose of the anode is to:
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Convert electrons into photons
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_ is the measurement of the number of electrons moving through a conductor
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Amperage
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Thermionic emission of the electrons occurs at the:
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Tungsten filament at the cathode
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Approximately what percentage of the kinetic energy of the electrons is converted to X-rays at the anode?
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Less than 1%
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The lead collimator
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Restricts the size of the xray beam
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What is true of general radiation?
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Also known as breaking radiation AND source of the majority of the X-rays that are produced
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Which form of the xray beam is most detrimental to the patient and operator?
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Primary radiation
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Which is the most common possibility when an xray photon interacts with matter?
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Compton scatter
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Which of the following four possibilities that can occur when an xray photon interacts with matter is responsible for producing densities on film that make dental radiography
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No interaction
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Critical organs exposed during dental radiographic procedures in the head and neck region include (1) skin (2) thyroid gland (3) lens of the eye (4) bone marrow
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1,2,3,4
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The traditional unit of dose is called:
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The radiation absorbed dose (rad)
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One gray is equivalent to _ rad(s)
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100 rads
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The SI equivalent if the rem is
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Sievert
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Naturally occurring background radiation includes:
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Cosmic and terrestrial radiation
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Uranium is an example of _ radiation
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Terrestrial
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