Lecture 4 Production of X-Rays Flashcards
Higher energy from source =
more x rays being produced
Increasing in MA =
Incr. in quantity of X-rays
KVP controls
energy of x-rays
Higher KVP =
higher attraction between cathode and anode
b/c e- will have higher velocity
mA controls
heating of the filament
Exposure time controls
quantity of x rays
because longer time means more are produced
kV controls
the acceleration of the e- from the cathode to the anode
KE=1/2mv^2
Electricity =
Flow of e- from an electrical conductor
Current =
amount of e- flowing through a conductor per second
measured in amperes (A)
Circuit =
path of the electrical current
can go to the right or the left
Voltage =
potential difference
the difference in electrical potential energy between two points in an electrical circuit measured in volts (V)
AC Power Supply
Alternating Power Current
Wall Power Plug in
Why AC instead of DC
AC lets you step up and step down
DC does not
More affordable
What is the direction e- travel
Cathode(+) to -> Anode (-)
What happens during each half cycle?
the anode is positive and attracts the e- form the cathode (x-radiation is produced)
What happens during each alternate ha;f-cycle?
anode is negative, therefore, no
attraction for electrons exists and no x-radiation is produced (inverse voltage).
What is a self rectifying tube?
.
What is full wave rectification?
.
produces x-rays all the time
What is half wave rectification?
.
What is constant potential?
.
How do you achieve constant potential?
- Changing alternating current into direct current
- Full-waive rectification, high frequency power supply
- Essentially constant potential between
cathode and anode. - Higher mean energy of beam compared to AC
Compared to Constant Potential, it will have a ____ compared to AC
higher mean energy
kVP is for
energy of e-
kEV is for
energy of x-rays
What are the benefits of Constant potential ad direct current?
- Shorter exposure times
- More Consistent beam intensity
- Higher mean energy of beam
- Deceased radiation dose
What is rectification
Rectification is the process of making AC to DC
How are x-rays produced?
.
What are the 2 types of interactions you can have to form x-rays
- Bremsstrahlung radiation
& - Characteristic radiation
How is Bremsstrahlung radiation formed?
Interaction of the e- with the nucleus
How is Characteristic radiation formed?
Formation of e- to e- interaction
e- interacts with tungsten
Bremsstrahlung radiation
e- comes to the nucleus
tungsten is the target
nucleus is positively charged attracted e- form the cathode
e- come to the nucleus, the direction gets deviated
the closer the e- to the nucleus, the greater the deviation
energy lost due to deviation creates X-Rays
More deviation =
more energy
if it stops (hits the nucleus) that is the maximum x-ray produced
T or F
All e- do not attain the same velocity
True
Some e- move at higher velocities than others depending on the kV
The higher the kV
the more energy and quantity of the X-rays
How does Bremsstrahlung radiation increase?
Bremsstrahlung radiation increases with increasing the voltage (kV) and the atomic number of the target (Z#)
Bremsstrahlung Radiation
Bremsstrahlung Radiation
1.) e- travels towards nucleus gets deflected (thrown off it's coarse while it gets closer) it slows down while it's deflected (Changing Directions) the more it changes it's direction, the more it deaccelerates, the stronger the x-ray that is emitted
2.)When an e- collides/hits a nucleus, the e- will be able to emit the maximum x-ray possible when the e- is brought to a complete stop
Bremsstrahlung Radiation
the higher the deviation
the stronger the x-ray that will be created
