Chapter 3 Flashcards
Dental x-ray machines contain each of the following components except one. Which one is the exception?
A) Control panel
B) Extension arm
C) Radioactive material
D) Tube head
C) Radioactive material
Which regulating device on the control panel measures the amount of current passing through the wires of the circuit?
D) mA selector
Each of the following conditions must exist for x-rays to be produced except one. Which one is the exception?
A) A target capable of stopping the electrons
B) An air-filled glass tube
C) High voltage to impart speed to the electrons
D) A source of free electrons
B) An air-filled glass tube
Which of the following is not a function of the tube head?
A) It allows all radiation to exit.
B) It provides grounding for the electrical components.
C) It protects the x-ray tube from accidental damage.
D) It prevents overheating of the x-ray tube.
A) It allows all radiation to exit.
The anode is composed of the focusing cup and the filament and must be charged negative during x-ray production.
D) Both parts of the statement are not correct.
How many electrical circuits are used in a dental x-ray machine?
B) Two
Sixty (60) impulses is equivalent to
D) 1 second
The intensity of the x-ray beam is affected by each of the following except one. Which one is the exception?
A) Target size
B) Kilovoltage
C) Exposure time
D) Milliamperage
A) Target size
Direct (DC) current is best suited for use with digital radiography and may produce more consistent exposures at the very short exposure times.
C) Both parts of the statement are correct.
Which of these statements is false?
A) The positive anode and negative cathode are sealed within the x-ray tube.
B) The control panel may be integrated with the x-ray machine tube head support.
C) The exposure button should be on the end of a 3 foot timer cord.
D) The x-ray tube contains a target capable of stopping the electrons.
C) The exposure button should be on the end of a 3 foot timer cord.
The duration of an x-ray exposure is determined by which control?
The timer controls how long the current flows through the x-ray tube.
The filament and target are made out of tungsten because tungsten
C) Withstands high temperatures
Which transformer corrects minor fluctuations in the current flowing through the wires?
C) Autotransformer
X-rays originate at the
D) Focal spot
Amperage measures the electric potential or force that moves electrons along a conductor. Increasing the force with which the electrons move increases the penetrating potential of the x-ray beam.
B) The first statement is false. The second statement is true.
Which of the following best describes how x-rays are actually produced in the dental x-ray tube?
D) High-speed electrons collide with target material electrons.
What percent of the kinetic energy inside the x-ray tube is actually converted to x-radiation?
D) 1 percent
Increasing which of the following would best increase the number of electrons flowing through the dental x-ray electrical circuit?
C) Milliamperage
Which of the following removes the soft x-rays from the x-ray beam as it exits the port?
B) Collimator
C) Filter
D) Transformer
C) Filter
How does the radiographer know when the x-ray exposure cycle is complete?
B) When the audible beep stops
Is electricity defined as electrons in motion?
TRUE
Does the metal housing of the tube head increase the safety of the x-ray machine?
TRUE
Does direct current flow in pulses and change direction?
FALSE
Is voltage the measurement of the number of electrons moving through a wire conductor?
FALSE
If the tube head is properly sealed, is the port the only place through which x-rays can escape?
TRUE
Is the x-ray beam formed at the focal spot monochromatic?
FALSE
Does the intensity of the beam refer to the quantity and quality of the x-rays?
TRUE
Is the filament on the negative side of the vacuum tube in a dental x-ray machine?
TRUE
Do dental x-ray machines have manual kVp and mA controls, or are they preset?
TRUE
Does the line switch on the control panel energize the low- and high-voltage circuits when in the “on” position?
FALSE
Does increasing amperage result in the production of more x-rays?
TRUE
Is the part of the cathode that directs electrons toward the tungsten target called the “focal spot”?
FALSE
Is the tungsten anode embedded in a core of copper to conduct heat away to a radiator?
TRUE
Is the small area on the tungsten target where the electron beam is directed called the “focal spot”?
TRUE
Does the step-down transformer correct fluctuations in the current flowing through the x-ray machine?
FALSE
Is the anode the negative electrode in the x-ray tube?
FALSE
Is the collimator a lead diaphragm that restricts the dimensions of the useful x-ray beam?
TRUE
Does thermionic emission refer to the release of electrons from the target material during incandescence?
FALSE
Does the primary beam refer to a high-energy, short-wavelength x-ray beam?
FALSE
Is an x-ray beam composed of many different wavelengths called “polychromatic”?
TRUE
