Dental Radiology NBDHE Exam Questions and
Answers
Wilhelm Roentgen - Answers-discovered the x-ray in 1895
he discovered x-rays while experimenting with a cathode ray tube
.ionization - Answers-the production of ions (an atom that gains or loses an electron and
becomes electrically unbalanced)
.ion pair - Answers-when an electron is removed from an atom in the ionization process
1. the atom becomes the positive ion
2. the ejected electron becomes the negative ion
.ionizing radiation - Answers-radiation that is capable of producing ions by removing or
adding an electron to an atom; x-rays produce ionization
1. particulate radiation
2. electromagnetic radiation
.particulate radiation - Answers-tiny particles of matter that possess mass and travel in
straight lines at high speeds
electrons
beta particles
cathode rays
protons
alpha particles
neutrons
.electromagnetic radiation - Answers-the propagation of wave-like energy (without
mass, without particles) through space or matter
cosmic rays
x-rays
microwaves, radio waves
gamma rays
ultraviolet rays
visible light
we want--short wavelength, high frequency
.velocity - Answers-the speed of a wave
, .wavelength - Answers-the distance between the crest of one wave to the crest of the
next wave
.frequency - Answers-the number of wavelengths that pass a point in a certain amount
of time
.X-ray - Answers-electromagnetic ionizing radiation of VERY SHORT WAVELENGTH
resulting from the bombardment of tungsten by highly accelerated electrons in a
vaccum
.properties of X-radiation - Answers-1. x-rays have a wave form; xrays travel in waves
with short wavelengths and high frequency
2. x-rays travel at the speed of light (186,000 miles/second)
3. x-rays have the power to penetrate substances
4. X-rays are invisible
5. x-rays have no mass, no weight and no charge
6. x-rays are absorbed by matter
7. x-rays exert an effect on living tissue; x-rays are able to stimulate or destroy living
cells
8. x-rays lose intensity with distance; x-rays travel in straight lines and cannot be
focused to a point
.The x-ray tube - Answers-1. protective leaded glass housing
tube enclosure with all the air removed; shielding prevents radiation leakage
high vacuum glass tube surrounded by refined oil with high insulating powers; the oil
helps to absorb excess heat
2. Cathode
3. Anode
Remember: inside the x-ray tube, electron stream travels from negative cathode to
positive anode
when the electrons strike the tungsten target, the energy of motion is converted to x-ray
energy and heat, 99% of the energy is lost as heat (and absorbed by insulating oil)
(negative cathode goes to positive anode)
.cathode - Answers-made of a tungsten filament and molybdenum cup; NEGATIVE
charge
filament: heated to give off a cloud of electrons; thermionic emission
cup: focuses electrons toward the anode
supplies the electrons necessary to generate x-rays
.anode - Answers-made of a copper arm and focal spot; POSITIVE charge
Answers
Wilhelm Roentgen - Answers-discovered the x-ray in 1895
he discovered x-rays while experimenting with a cathode ray tube
.ionization - Answers-the production of ions (an atom that gains or loses an electron and
becomes electrically unbalanced)
.ion pair - Answers-when an electron is removed from an atom in the ionization process
1. the atom becomes the positive ion
2. the ejected electron becomes the negative ion
.ionizing radiation - Answers-radiation that is capable of producing ions by removing or
adding an electron to an atom; x-rays produce ionization
1. particulate radiation
2. electromagnetic radiation
.particulate radiation - Answers-tiny particles of matter that possess mass and travel in
straight lines at high speeds
electrons
beta particles
cathode rays
protons
alpha particles
neutrons
.electromagnetic radiation - Answers-the propagation of wave-like energy (without
mass, without particles) through space or matter
cosmic rays
x-rays
microwaves, radio waves
gamma rays
ultraviolet rays
visible light
we want--short wavelength, high frequency
.velocity - Answers-the speed of a wave
, .wavelength - Answers-the distance between the crest of one wave to the crest of the
next wave
.frequency - Answers-the number of wavelengths that pass a point in a certain amount
of time
.X-ray - Answers-electromagnetic ionizing radiation of VERY SHORT WAVELENGTH
resulting from the bombardment of tungsten by highly accelerated electrons in a
vaccum
.properties of X-radiation - Answers-1. x-rays have a wave form; xrays travel in waves
with short wavelengths and high frequency
2. x-rays travel at the speed of light (186,000 miles/second)
3. x-rays have the power to penetrate substances
4. X-rays are invisible
5. x-rays have no mass, no weight and no charge
6. x-rays are absorbed by matter
7. x-rays exert an effect on living tissue; x-rays are able to stimulate or destroy living
cells
8. x-rays lose intensity with distance; x-rays travel in straight lines and cannot be
focused to a point
.The x-ray tube - Answers-1. protective leaded glass housing
tube enclosure with all the air removed; shielding prevents radiation leakage
high vacuum glass tube surrounded by refined oil with high insulating powers; the oil
helps to absorb excess heat
2. Cathode
3. Anode
Remember: inside the x-ray tube, electron stream travels from negative cathode to
positive anode
when the electrons strike the tungsten target, the energy of motion is converted to x-ray
energy and heat, 99% of the energy is lost as heat (and absorbed by insulating oil)
(negative cathode goes to positive anode)
.cathode - Answers-made of a tungsten filament and molybdenum cup; NEGATIVE
charge
filament: heated to give off a cloud of electrons; thermionic emission
cup: focuses electrons toward the anode
supplies the electrons necessary to generate x-rays
.anode - Answers-made of a copper arm and focal spot; POSITIVE charge
