Principles of Radiology Flashcards
What are x-rays? Examples? (4)
- A form of electromagnetic radiation
- Examples:
- Gamma rays
- Radio waves
- Visible light
- TV waves
What is a radiograph?
An image produced on film due to x-rays
How do electromagnetic waves move?
In an X & Y axis
T/F: X-rays have a shorter wavelength than visible light, therefore they can penetrate object when visible light is reflected or absorbed
True
What is it in X-rays that allows certain materials to fluoresce?
Photons do this, they cause “excitement.”
Therefore, we can record images
T/F: Light and X-rays act like waves traveling thru space
True
T/F: Light and X-rays act like particles when interacting with matter
True
T/F: Light and X-rays don’t travel in straight lines
False. They don’t, therefore, they cannot go around corners
T/F: Light and X-rays diverge from a point source
True
T/F: X-rays are affected by magnetic fields
False! They are NOT affect by magnetic fields
T/F: X-rays travel at the speed of light
True
Where do X-rays come from? How does it work?
- An x-ray tube!
- How it works:
- Fast moving electrons hit a metal target
- 99% of energy is converted to heat
- 1% of energy is converted to x-rays
Basic parts of the x-ray tube (4)
- Air evacuated glass chamber
- Cathode
- Anode
- Cooling mechanism
Air evacuated glass chamber
Prevents electrons from colliding with air molecules
Cathode
Source
How it works
- Source of electrons
- Negative end - 1-2 wire filaments within wells of focusing cup
- Filaments are heated to critical temp and electrons are boiled off.
These electrons are then accelerated toward the anode
Anode
- Target for electrons from cathode
- Where x-rays are created
- Positive end
Focal spot
- A small focal spot produces a more detailed image
- Small filaments produce limited number of electrons
Effective focal spot
Angling the target a small degree will produce a small effective focal spot
Heel effect
- Angled anode leads to more energy on cathode side of beam due to partial absorption of beam into anode.
- Therefore, one should place thicker body parts toward the cathode side of the beam to produce more uniform image
T/F: One should place thicker body parts toward the cathode side of the beam to produce more uniform image due to the Heel Effect
True
T/F: Cooling mechanisms are required in x-ray machines because filament may get as hot as 3000 F
True
T/F: Stationary anode has a tungsten target embedded in block of copper. This design is used in dental & portable x-rays
True
T/F: Rotating anode won’t dissipate heat and makes a larger focal spot. This will increase image detail
False.
It WILL dissipate heat and makes a SMALLER focal spot that will INCREASE image detail
In regards to X-ray care, do not… (4)
- Drop or hit xray tube
- Leave machine on continuously
- Hold down the rotor “ride the rotor”
- Make too many high energy exposures in rapid succession
