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138 Cards in this Set
- Front
- Back
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Who discovered x-rays?
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Wilhelm Roentgen
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Who discovered radioactivity?
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Henri Becquerel
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In what year did Roentgen discover x-rays?
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1895
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In what year did Becquerel discover radioactivity?
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1896
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What are electric sparks given off by a Crookes tube?
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cathode rays
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What were the screens with which Roentgen was working made of?
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barium platinocyanide
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What are wavelike fluctuations of electric and magnetic fields set up in space by oscillating electrons?
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electromagnetic radiation
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What is the distance between two successive crests or valleys on a sine wave?
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wavelength
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What is the number of crests or cycles per second?
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frequency
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What is the name of a frequency of one cycle per second?
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Hertz
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What is the formula that expresses the inversely proportional relationship between frequency and wavelength?
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speed of light = frequency x wavelength
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The relationship between frequency and wavelength is _________ proportional.
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inversely
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As the _________ increases, the wavelength decreases.
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frequency
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As the frequency increases, the __________ decreases.
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wavelength
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As the frequency _________ the wavelength _________.
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increases / decreases
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What is considered to have the highest energy in the electromagnetic spectrum?
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Cosmic rays
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What is considered to have the lowest energy in the electromagnetic spectrum?
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radio
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In the electromagnetic spectrum, what has an energy that is higher than gamma rays but lower than cosmic rays?
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therapy x-rays
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In the electromagnetic spectrum, what has an energy that is higher than diagnostic x-rays but lower than therapy x-rays?
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gamma rays
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In the electromagnetic spectrum, what has an energy that is higher than ultraviolet light but lower than gamma rays?
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diagnostic x-rays
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In the electromagnetic spectrum, what has an energy that is higher than visible light but lower than diagnostic x-rays?
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ultraviolet light
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In the electromagnetic spectrum, what has an energy that is higher than infrared but lower than ultraviolet light?
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visible light
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In the electromagnetic spectrum, what has an energy that is higher than radar but lower than visible light?
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infrared
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In the electromagnetic spectrum, what has an energy that is higher than television but lower than infrared?
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radar
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In the electromagnetic spectrum, what has an energy that is higher than radio but lower than radar?
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television
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Electromagnetic radiations are said to have a _________ nature.
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dualistic
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Electromagnetic radiations are called _______ or quantum.
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photons
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Photons are classified by their ______ rather than their wavelength.
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energy
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In their behavior, to what are gamma rays identical?
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x rays
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What is the kinetic energy of a stream of fast moving electrons change into when interacting with the atoms of an x-ray tube target?
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x-rays and heat
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What controls the amount of electrons being boiled off?
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mA
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Invented in 1913, this x-ray tube was the first hot cathode diode tube?
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Coolidge tube
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What is the process of boiling off electrons from a filament?
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thermionic emission
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What is the name of the electron cloud that forms around the cathode?
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space charge
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What is the name of electrons that are liberated from the cathode?
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thermions
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What is the name of x-rays that exit through the window of the x-ray tube?
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useful beam
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What is the name of x-rays that leave the x-ray tube housing?
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leakage radiation
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What is the name of the place on the anode face where the electron stream is focused?
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focal spot
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What is the negatively charged object that surrounds the filament?
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focusing cup
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What percentage of the electrons kinetic energy is converted to heat?
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99.4
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What percentage of the electrons kinetic energy is converted to x-rays?
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.6
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What type of x-rays does Brems radiation produce?
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heterogeneous or polyenergetic
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What determines the efficiency of x-ray production?
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the atomic number of the target
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What are the two most common materials used for x-ray targets?
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Rhenium (75) and Tungsten (74)
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What are wavelike fluctuations of electric and magnetic fields set up in space by oscillating electrons?
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electromagnetic radiation
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What is the symbol for wavelength in m?
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lambda (λ)
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What is the speed of light?
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3 x 10^8 meters, 3 x 10^10 cm, or 186,000 miles per s in a vacuum
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Translate the following formula: c=fλ
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the speed with which a wave travels is equal to the frequency multiplied by the wavelength
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In the formula c=fλ, what does the ‘c’ represent?
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speed of x-rays or light in a vacuum or air
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In the formula c=fλ, what does the ‘f’ represent?
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frequency in hertz or HZ (cycles/s)
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In the formula c=fλ, what does the ‘λ’ represent?
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wavelength in m (meters
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What is the speed of all electromagnetic waves?
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c
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Are the wavelengths of x-rays long or short?
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extremely short
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Is it preferable to designate x and gamma rays according to their photon energy or their wavelength?
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photon energy
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How is air removed from the glass and metal parts of an x-ray tube?
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degassing
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Which unit expresses an amount of charge released per unit mass of air specifically?
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Roentgen
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Does x ray exposure refer to quantity or quality?
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quantity
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In x ray production, why is most of the electrons energy degraded to heat?
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because of collision with out shell electrons of the tungsten atoms
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What is the equation that states the efficiency of x ray production?
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% efficiency = K x Z x kVp
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In the equation % efficiency = K x Z x kVp, what does the ‘K’ represent?
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a constant of 1 x 10^-4
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What are the two ways in which x rays behave?
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as waves and particles
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Are x rays electrically positive, negative or neutral?
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neutral
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Can x rays be deflected by electric or magnetic fields? Why or why not?
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no, because they are electrically neutral
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What are the two most important characteristics of metals used for x ray tube targets?
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high melting point and high atomic number
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What accounts for 90% of emitted x rays when 80-100 kV is applied?
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Bremsstrahlung
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What accounts for 10% of emitted x rays when 80-100 kV is applied?
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characteristic radiation
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What are the two processes by which x rays are produced?
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Brems and characteristic radiation
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What is the name of the x rays that leave the window of the x ray tube?
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useful beam
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What is the name of an x ray tube’s negative electrode?
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cathode
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What is the name of an x ray tube’s positive electrode?
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anode
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What does it mean to have a wide span of energies and wavelengths?
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\polyenergetic
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How do x rays travel ordinarily?
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in straight lines
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At what speed do x rays travel?
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the speed of light
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How do x rays indirectly ionize gas?
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in their ability to remove orbital electrons from atoms
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Can x rays be focused by a lens?
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no
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What do x rays cause in certain crystals making possible their use in radiographic intensifying screens and other modalities?
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fluorescence
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What types of images are the affect of x rays on photographic film?
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latent
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What are the two properties with which x rays can be described?
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intensity and quality
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What is the international unit of exposure based on ionization in air?
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Roentgen
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What describes the percentage of kinetic energy of the electrons that is converted to x rays?
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efficiency of radiation production
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What factor(s) is (are) directly proportional to the efficiency of radiation production?
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atomic number of the target and the applied kilovolt potential
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In which units the energy of monoenergetic radiation expressed?
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electron volts (eV)
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What is the name of a recorded image produced by x rays on photographic film?
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radiograph
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What are rays of high energy (photons) having no mass?
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x rays
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What is the top of a wave called?
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crest
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What is the speed of light?
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186,000 mi./sec. or 3 x 10^10 cm./sec.
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What is the distance between two crests?
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wavelength
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How do electromagnetic waves travel?
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in straight lines
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What is the number of crests passing a fixed point per second?
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frequency
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What is wavelength of an average diagnostic x ray in Angstroms?
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0.5
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What is produced when fast-moving electrons are slowed or stopped suddenly?
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x rays
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What is the source of electrons in an x ray tube?
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cathode
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What are the two components on the negative side of an x ray tube?
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tungsten filament and focusing cup
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What is also term for ‘useful beam’?
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primary beam
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What is the flow of electrons through a conductor?
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current
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What is the unit that measures current?
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amps or amperes
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What is another word for ‘voltage’?
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potential difference
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What is a measurement of the force which drives electric current through a conductor?
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voltage / potential difference / electromagnetic force
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What is the space between a cathode and anode?
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tube gap
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What drives electrons across the tube gap?
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high voltage
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What is the typical voltage to drive electrons across the tube gap?
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kilovolts
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What is the typical range for x ray tube current?
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20 - 150 kV
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In the context of x rays, what type of ability do kilovolts have?
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penetrating
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What is the way in which current always flows?
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from negative to positive
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Filament current has…
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low voltage and high amperage
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In x ray production, what controls the amount of electrons that are boiled off?
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filament current
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What does mA stand for?
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milliamps
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What results in a large focal spot with a greater heat capacity?
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large filament
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What results in a small focal spot with lower heat capacity?
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small filament
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Which control adjusts the filament current?
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mA control
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What measures the tube current, and the number of electrons crossing the tube gap during the exposure?
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mA measurement
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What does kV stand for?
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kilovoltage
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What must be rotating at full speed before kV, making an exposure?
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anode
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What does λ stand for?
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wavelength / lambda
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What does ν stand for?
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Frequency / nu
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What types of x rays are produced when fast moving electrons undergo rapid deceleration?
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Bremsstrahlung
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What does the MAS measure?
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density
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No characteristic radiation occurs at KVp’s under ______.
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69
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What is located inside the glass envelope and is attached to the anode disk by a molybdenum shaft?
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rotor
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In an x ray tube, what helps to prevent spark over and remove heat from the tube?
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insulating oil
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What aspect of an x ray do mA and time control?
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quantity
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In a Coolidge tube, a high voltage is applied across the electrodes charging the filament _______ and the target _______.
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negatively/positively
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What is the only part of the cathode or anode assemblies that is located outside the vacuum of the glass envelope?
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stator
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What is the melting point of tungsten?
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3370 degrees C
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What is the KVP?
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the peak voltage in an AC current
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What is Planks constant?
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12.4 (h) for KeV
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Who is characteristic radiation calculated?
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by subtracting the binding energy of the K or L shell electron minus the binding energy of the outer shell (MNOP) electron
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What is the binding energy of the K shell for tungsten?
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69 KeV
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What controls the quality of x rays?
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KV
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What controls the quantity of x rays?
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mA
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On an anode, what does the degree of angle influence?
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the size of the exposure that can be used for short exposure times without damaging the x ray tube
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What measures the tube current and the number of electrons crossing the tube gap during exposure?
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mA Measurement
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What were the first x ray tubes?
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Crookes Tubes
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What are the three typical target angles?
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10, 12 and 17 degrees
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What formula pertains to the density of a radiograph?
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mAS
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What types of x rays are produced when electrons drop from an outer shell to a vacancy in an inner atomic shell?
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characteristic x ray
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What is the formula for the thermal capacity of an anode in a single-phase operation?
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H.U. = kVp x mA x time in s
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What is the formula for the thermal capacity of an anode in a 3-phase operation?
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H.U. = kVp x mA x time in s x 1.35
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