Introduction to Imaging Flashcards
Why is imaging used?
Physical examination is unreliable
Different tests are good for different things
Faster diagnosis
Assess response to treatment
What is triage?
Identify who is going to benefit most from surgery and other treatment
What is screening?
Identify diseases at an early stage to intervene
What is an X-ray?
Electromagnetic packet of energy with a short wavelength between 0.1 and 10nm
What can an atom be defined by?
Mass number A
Atomic number Z
Nucleus
Electrons
What is the mass number?
Amount of protons and neutrons
What is the atomic number?
Amount of protons
Where do gamma rays come from?
The nucleus
What are the layers of electrons around the nucleus known as?
Inner and outer shell
What causes the electrical and chemical properties of an atom?
Outer shell of electrons
What is responsible for the production of X rays?
Inner shell of electrons
How does an X ray work?
- Cathode heated to 2200oC to produce a stream of electrons
- Travel to T which is positively charged, crossing a vacuum
- 0.1% of energy creates X rays, rest is heat, rotar (r) and S makes sure the disk spins quick
- O and E controls the heat and B allows it to expand
- X rays travel down the LED glass/window
What does the intensity of the X ray depend on?
Tube current
Atomic number of target
Tube voltage
What are the 3 paths of an X ray once it interacts with matter?
Absorption
Transmission
Scatter
What is attenuation?
Process by which radiation loses power as it travels through matter and interacts with it
What does attenuation depend on?
Atomic number
Density
Thickness
How do X rays interact with air?
Travel all the way through