Test 3 Chapters 5-6 Flashcards
3 components of X-ray imaging system:
Operating console
X-ray tube
High voltage generator
X-ray imaging systems operate voltages in the range of
25-150 KvP
100-1200 mA
The high voltage generator is always close to…..
mA is related to _________
The X-ray tube
X-ray tube current
Radiation quantity =
Radiation quality =
X-ray intensity
And calculates NUMBER of X-rays in mGy or mAs
X-ray penetrability
The ENERGY calculated in kvp or half value layer
AEC
Automatic exposure control
Electric circuits that connect the meters and controls which are at low voltage to minimize possible hazardous shock
Measures the voltage provided to the X-ray imaging system and adjusts the voltage to 230 V
Line compensator!
To keep kVp CONSTANT!!
Has one winding one core to supply precise voltage to the filament circuit and high voltage circuit
Autotranformer
All electric circuits are ______________ to prevent shock
Low voltage
Cathode
Anode
In the X-ray tube
Cathode is negative and is connected to filament
Anode is positive
As kvp raises, anode becomes more attracted to electrons that do NOT leave the
Filament
As kvp increases, a greater percentage of thermionically emitted electrons go toward the anode
Saturation current
THe more electrons released, the more HEAT
Thermionic emission
The release of electrons from a heated filament
*frequency of 60Hz or 1/60s
(Cannot be used for serial exposures)
- most accurate for several exposures(X-rays)
- will shut off when appropriate density is reached
- will shut off exposure after a prescribed time (usually 6seconds)
- terminates X-ray when the image receptor has received the appropriate radiation intensity.
Synchronous
Electronic
mAs
Guard
AEC
The high voltage generator contains 3 primary parts:
The high voltage transformer
The filament transformer
Rectifiers
What is rectification ?
The process or device used in converting AC to D.C.
X-rays need direct current (DC) !!
Voltage rectification is required to ensure that _______ flow from the ____________ cathode to anode ONLY.
Electrons
X-ray tube
An electron device that contains two electrodes:
A diode
A diode rectifier are made of silicon
Semi conductors have two types:
N-type (are free n loosely bound)
P-type (have spaces called holes and no electrons)
A solid p-n junction and conduct electricity in—–direction
Aka (solid state diode)
One !
On the secondary side of wave
Contains one or more diodes and is not allowed on negative side
UNrectified voltage
Half wave rectification
The current that passes through the X-ray tube is only the ——- Half of the cycle wave
Positive side
The voltage supplied to the X-ray tube are nearly ________ using the three phase power
Constant!
Single phase power results in a ——- X-ray beam
Pulsating
These have low voltage or low penetrability
The high frequency (500-25,000Hz)generator contain nearly constant voltage potential and are ——-
Smaller in size than the 60Hz generator
Are used in almost all stationary X-ray imaging systems:
Full wave rectification and high frequency voltage generators
Falling load generators are to ensure
Shortest possible exposure time!!
MAs timer
Less voltage ripple results in
Greater radiation quantity and quality !
X-ray tube consists of 3 parts:
The support structure
The protective housing
The glass or metal enclosure
The internal structures of the X-ray tube are
The anode and cathode
The source of X-rays in the X-ray tubes?
From the focal spot
External structure of the X-ray tube
Support structure
Protective housing
Glass envelope
X-rays that emit at the same intensity
Isotropically
Shuts off X-rays after determined # of X-rays have hit the sensor
AEC
Has to be less than 100mR/he at 1 meter
Leakage
Oil serves as an __________ so that the X-ray tube doesn’t overheat
Insulator
Electrons that are boiled off; then heats and forces electrons to go
The filament
Filaments and the cathode are made of __________
A diode is made of ___________
Tungsten
Silicone
Rectifiers are located in the ___________ winding and are processed with __________ to force the electrons to go in one direction aka __________
Secondary
Diodes
AC/DC
Ionization chamber measures the
Radiation!!!!
Step up transformer is located in the ——— and its job is to convert
Secondary/high voltage
Voltage to KvP
Amperage to milliamperes he
Where is the auto transformer located? And what does it do
Control console/primary side
Selects KvP
AEC is a safety feature to prevent
Over exposure
What is the % of Three phase 12 pulse?
4% ripple and is the most dense
High frequency generators have a percentage of ?
1 %
The __________ the KvP
And the ________ mAs is less radiation exposure
Higher
Lower
What is on the primary side
Control sonsole
Line compensator
Autotransformer
