8/20: Production of X-Rays Flashcards
- What are the numbers listed on the X-ray machine?
a. Exposure time
b. kVp
c. mA selectors
d. Exposure button
e. Indicator light and audible signal
- What are the parts of the X-ray machine?
a. Control panel
b. Tube head
c. Extension arm
- What is the tube head composed of?
a. Power supply + x-ray tube
- Is the cathode or anode associated with the step-down transformer?
Cathode
- Is the cathode or anode associated with the step-up transformer?
Anode
- What liquid surrounds the cathode and anode?
a. Insulating oil
- The x-ray beam must pass through what?
a. Aluminum filter
- What 2 things are in a cathode?
a. Filament
b. Focusing cup
- What is the cathode filament made of?
a. Tungsten
- What is the source of the electrons in the cathode?
a. filament
- The filament in the cathode emits what?
a. Electrons
- The cathode is heated with a low voltage source and emits electrons at a rate proportional to its temperature. This is known as (step-down transformer will control heat!!!!!!!!!)
a. Thermionic emission
- What is the cathode focusing cup composed of?
a. Molybdenum
- What is true regarding the step-down transformer?
a. Controls heat to cathode (thermionic emission)
- The focusing cusp focuses the electrons into a
a. Focal spot
- Is the cathode positive or negative?
Negative
- Is the anode positive or negative?
Positive
- What 2 things make up the anode?
a. Tungsten target
b. Copper stem
- The focal spot is located on the
a. Tungsten target of the anode
- Where do the electrons hit
a. Tungsten target on the anode
- This transforms the kinetic energy of the colliding electrons into x-ray photons
a. Tungsten target
- What occurs at the tungsten target?
a. Produces X-rays
- Is the tungsten target efficient or inefficient?
a. Inefficient 99%, 1% efficient
- The tungsten target is attached to what part of the anode?
a. Copper stem
- This works as a thermal conductor to remove the heat from the tungsten avoiding target melting
a. Copper stem
- Why is tungsten a good target material?
a. High atomic number
b. High melting point
c. High thermal conductivity
d. Low vapor pressure
- What are the conditions necessary for X-ray production?
a. Separation of electrons
b. Production of high-speed electrons
c. Concentration of electrons
d. Sudden stoppage of electron steam
- Does having a higher atomic number help with efficient production of X-rays
Yes
- Separation of electrons is called
a. Thermionic emission (in the cathode filament)
- High potential difference is produced between the cathode and anode by applying what
a. High voltage between them
- To what speed are electrons accelerated?
a. 0.5x speed of light
- What does the copper stem do to the tungsten?
a. Remove the heat because it is an inefficient process
- Do you want a bigger or smaller focal spot?
a. Smaller
- Why is size important for the focal spot?
a. The smaller = higher spatial resolution
- The smaller the focal spot, the heat _____
a. Accumulates
- When the focal spot is smaller, you get more heat accumulation. What 2 ways can you overcome this problem?
a. Rotating anodes
b. Stationary anodes
- Stationary anodes are also known as what principle?
a. Line-focus principle
- This allows heat at the focal spot to spread out over a large surface
a. Rotating anode
- Rotating anodes can be identified by
a. Dark band
- Rotating anodes are used in
a. Medical devices
- This is when you angle the target to achieve a smaller effective focal spot than the actual focal spot
a. Line-focus principle (stationary anode)
- The projection of the focal spot perpendicular to the target
a. Actual focal spot
- the projection of the focal spot perpendicular to the electron beam
a. Effective focal spot
- What is true of Stationary anode (life-focus principle)?
a. The effective focal spot is smaller and has sharper resolution
- In the line-focus principle, what is smaller?
a. Effective focal spot
- This provides a low-voltage current to heat the x-ray tube filament
a. Step-down transformer
- This generates a high potential difference to accelerate electrons from the cathode to the anode
a. Step-up transformer
- This is a electromagnetic device that either increases or decrease the voltage on a circuit
a. Transformer
- What are the 3 types of transformers in an X-ray device?
a. Step-down
b. Step-up
c. Autotransformer
- This is a filament transformer
a. Filament transformer
- This is a high voltage transformer
a. Step-up
- The step-down transformer is regulated by
a. mA switch
- The step-up transformer is regulated by
a. kV setting
- Increasing the number of electrons emitted
a. Increasing mA
- Increasing the energy of the electrons traveling from the cathode to anode
a. Increasing kV
- kV is associated with what?
a. High voltage, step-up transformer
- mA is associated with what?
a. Low voltage, step-down transformer
- This determines the amount of time the high voltage circuit is applied across the x-ray tube
a. Exposure time
- This is the delay of 1⁄2 of a second to heat the filament
a. Time delay circuit
- This is the actual time of exposure
a. Timing circuit
- Few coils to many coils =
a. Step-up transformer
- Many coils to few coils =
a. Step-down transformer
- Low-voltage =
a. Step-down
- High voltage =
a. Step-up
- This controls the acceleration of electrons from the cathode to the anode
a. kV (kilovoltage)
- This controls heating of the filament
a. mA (milliamperage)
- This controls the time in which x-rays are produced
a. Exposure time
