1
Q
High Voltage Generators
A
radiation quantity and quality produced in the x-ray tube are influenced by the type of high voltage generator used
2
Q
What are the different types of generators?
A
- Single Phase (half-wave and full-wave rectified)
- Three Phase (half-wave and full-wave rectified)
- High Frequency
3
Q
Single Phase Generators Half-Wave Rectified
A
- half of electrical cycle wasted
- x-ray produced only half the time
- 100% ripple
- used in mobile radiography and dental
4
Q
Single Phase Generators Full-Wave Rectified
A
- Voltage wave-form same as half-wave but there is no dead time
- X-rays are emitted continuously as a pulse
- Required exposure time is half that for half-wave
- 100% ripple
5
Q
Three-Phase Generators
A
- phases 120 degrees apart
- more efficient than a single phase
- more x-rays–> more mAs—> greater energy
- x-ray production constant rather than pulsed
- 14% ripple
6
Q
Three Phase Power Half Rectified
A
6 pulse
7
Q
Three Phase Power Full Rectified
A
12 pulse, 4% ripple
8
Q
High-Frequency Generators
A
- developed in 1980s
- near constant potential
- Less than 1% ripple
- used in mammography and CT
9
Q
Voltage Ripple
- Variation in peak voltage waveform
- single phase —> _______ ripple
- 3 phase/6 pulse —-> __________ ripple
- 3 phase/ 12 pulse —–> ________ripple
A
- 100%
- 14%
- 4%
10
Q
Less ripple —> greater ________ —> less _______
A
- greater efficiency
- less patient exposure
11
Q
shorter exposure times may be used with ______
A
3 phase
12
Q
3 phase comparison to 1 phase
- provides for shorter exposure times
A
- 3 phase more efficient than 1 phase
- 3 phase requires more complex circuitry
- 3 phase more expensive to install
