Dental Radiology NBDHE UPDATED
ACTUAL Exam Questions and CORRECT
Answers
Wilhelm Roentgen - CORRECT ANSWER - discovered the x-ray in 1895
he discovered x-rays while experimenting with a cathode ray tube
ionization - CORRECT ANSWER - the production of ions (an atom that gains or loses an
electron and becomes electrically unbalanced)
ion pair - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - the speed of a wave
wavelength - CORRECT ANSWER - the distance between the crest of one wave to the
crest of the next wave
frequency - CORRECT ANSWER - the number of wavelengths that pass a point in a
certain amount of time
X-ray - CORRECT ANSWER - electromagnetic ionizing radiation of VERY SHORT
WAVELENGTH resulting from the bombardment of tungsten by highly accelerated electrons in
a vaccum
properties of X-radiation - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - made of a copper arm and focal spot; POSITIVE charge
ACTUAL Exam Questions and CORRECT
Answers
Wilhelm Roentgen - CORRECT ANSWER - discovered the x-ray in 1895
he discovered x-rays while experimenting with a cathode ray tube
ionization - CORRECT ANSWER - the production of ions (an atom that gains or loses an
electron and becomes electrically unbalanced)
ion pair - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - the speed of a wave
wavelength - CORRECT ANSWER - the distance between the crest of one wave to the
crest of the next wave
frequency - CORRECT ANSWER - the number of wavelengths that pass a point in a
certain amount of time
X-ray - CORRECT ANSWER - electromagnetic ionizing radiation of VERY SHORT
WAVELENGTH resulting from the bombardment of tungsten by highly accelerated electrons in
a vaccum
properties of X-radiation - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - made of a copper arm and focal spot; POSITIVE charge
