Imaging Systems Flashcards
Electric ground
Neutral object ready to receive electrons; reference point in an electrical circuit from which voltages are measured
Autotransformer
Variable ratio transformer, single iron core, self induction, supplies a precise voltage to the filament circuit and to the high voltage circuit
Voltage/electromotive force
AKA Potential, potential difference;
The force that propels electrons
Amperage
AKA current/impedence;
The number of electrons in motion
1 Amp = 6.3x10 to the 18th power electrons per second
Direct current
Electrons flowing in a single direction, constant magnetic field
Alternating current
Electrons flowing in a back/forth motion, changing magnetic field
Transformer
Reconfigures wattage from primary or secondary.
More turns = stronger magnet
Rectifier/diode
Changes AC to DC, 4 rectifiers required
Capacitor
Stores electric charge temperature temporarily
Line compensator
Adjusts incoming voltage to the precise voltage value that the system is designed to operate on.
Line = what the power company sends us
Major KVP selector
Selector in steps of 10kv
Minor KVP selector
Selector in steps of 1-2kv
Rheostat
Absolute resistor used to adjust current of the varying resistance in an electric circuit.
Example = light dimmer switch
mA selector
Controls current that goes to the filament
Focal spot selector
Determines which filament it will use to transfer anode to cathode
Line monitor
Instrument used to analyze signal coming in
Filament transformer
AKA step down transformer
High voltage transformer
AKA step up transformer
KVP meter
Instrument used to measure X-ray generator tube potential
Mechanical timer
Exposure timer that is wind up
Synchronous timer
Exposure timer that measures the number of voltage pulses, capable of 1/120th of a second
Electronic timer
Exposure timer that is capable of 1/1000th of a second
mAs timer
Exposure timer that delivers a selected mAs without setting the time
mA meter
Instrument used to measure mA in a circuit
Voltage ripple
How far voltage falls from its peak, least amount of ripple desired
Power rating
The maximum mAs x maximum KVP
High voltage generator
Increases voltage to kilo lots, increases amperage for thermionic emission, converts AC to DC
Half wave rectification
Only positive cycle of AC waveform
1/120th of a second dead time between pulses
60 pulses per second
100%voltage ripple
Full wave rectification
Both positive and negative
120 pulses per second
100% voltage ripple
3 phase, 6 pulse generation
3 independent voltage wave forms, timed to work together in phase
360 pulses per second
13% ripple
3 phase 12 pulse generation
3 independent voltage wave forms timed to work together in phase
720 pulses per second
4%ripple
High frequency generation
Modern system of powering an X-ray system
Creates “square” waveforms of extremely high frequency creating highly efficient power.
Only 1%voltage ripple
3 things for X-ray production
Source of free electrons
Acceleration of free electrons
Abrupt haltingly high speed electrons
Operators console
First of three sections of an imaging system.
Low voltage and amperage
Personnel safety
High voltage generator section
Second of third section of an imaging system
High voltage and amperage
Remotely located for safety
X-ray tube
3rd of 3 section on the imaging system
High voltage and amperage
Insulated for safety
mAs
of X-rays in the beam
KVP
Refers to the penetrability of the beam
Exposure time
How long voltage is applied
- current will flow only when voltage is applied
More turns
Stronger magnet
Stronger magnet
Higher voltage
Step up transformer
Voltage is increased from primary to secondary
Step down transformer
Voltage is decreased for primary to secondary
Transformer stepping
How voltage is affected from primary to secondary
Ratio greater than1
Step up transformer
Ratio less than 1
Step down transformer
Cathode
Negative
Uniquely designed to emit electrons - but not receive
Anode
Positive
Uniquely designed to receive electrons - but not to emit
Filament current
Amperage delivered to filament for thermionic emission
mA
Tube current
Electrons traveling from cathode to anode
mAs
X-ray tech controls
When X-rays are created (exposure switch)
Strength of X-rays created (KVP adjustment)
How many X-rays created (mAs adjustment)
For how long X-rays are created (exposure timer)
How X-rays are created
X-ray machine is a device that converts one form of energy that we have in abundance into the form of energy we want: Electrical energy Thermal energy Potential energy Kinetic energy Electromagnetic energy
Density
Overall blackening of a film/image
Energy deposited into the image receptor
High contrast
Black and white, few grays
Low contrast
Image with many grays
Half wave rectification has how many pulses?
How much ripple?
60/sec
100%
Full wave rectification has how many pulses?
How much ripple?
120/sec
100%
3 wave, 6 pulse has how many pulses?
How much ripple?
360/sec
13%
3 wave, 12 pulse has how many pulses?
How much ripple?
720/sec
4%
How much ripple in a high frequency generation?
1%
