chapter 6 (The x ray imaging system ) Flashcards
A falling load generator allow for a _________ exposure when compared to a fixed mA.
Shorter
A________ transformer is used to increase filament current.
Step- down
The unrectified voltage waveform _________before the x ray tube.
has both a positive and negative component.
which of the following is a disadvantage of a three phase power compared to a single phase?
Higher costs
what material are most patient tables made of ?
Carbon fiber
Assuming the same maximum kvp and mAs, the power rating of a single phase system is ______ a three phase system.
less than
_________ is a voltage waveform that results in thousands of pulses per second after rectification.
High frequency
A three phase waveform has _______ ripple.
13%
The x-ray tube current is monitored on the __________.
secondary side of the high voltage transformer.
with half wave rectification current flows through the x ray tube during the ________part of the cycle.
positive
The difference in waveform between primary and secondary sides of the high voltage transformer is _______
Amplitude
Full wave rectifiers use both the positive and negative parts of a wave, which __________.
cuts the exposure time in half
The_____ timer operates based on a wound spring.
mechanical
The autotransformer has_____ coil(s).
one
The most accurate type of timer is the ________ timer.
Electronic
which statement is true about machines using a half-wave rectified voltage waveform?
All of the above.
- they require twice the exposure time of full- wave rectified circuits.
- Electrons are accelerated from the cathode to anode of the x ray tube in the positive voltage cycle.
- they do not operate in the negative portion of the waveform
- they have a 100% ripple.
________ require a back up timer.
AEC timers.
Variations in power distribution to the x ray machine are corrected by the _________.
line voltage compensator.
The three main parts of the x ray imaging system are the ________, ________ and ________.
- X- ray tube
- operating console
- high voltage generator.
As the number of pulses increase over a fixed time, the ripple______.
decreases.
When high voltage is on the cathode side of a vacuum tube rectifier, _______.
there is NO current flow
The automatic exposure control (AEC) terminates the exposure when ________.
sufficient radiation reaches the image receptor.
The generator that produces the least penetrating x rays and results in a highest radiation dose to the patient for the same kvp is the _______.
single phase half wave rectified.
The voltage waveform supplied to the primary side of the high voltage transformer is________.
unrectified
The first component to receive power in the x ray circuit is the ________.
autotransformer.
The rectification process converts ________.
AC to DC
A high frequency waveform has _____ ripple.
1%
What is the industry standard formula for calculating high voltage generator power rating?
Power= f x max mA (@100kvp and 100 ms) x 100 kvp.
An autotransformer has a primary current of 800 mA. If there are 350 turns on the primary side and 460 turns on the secondary side, what is true about the transformer?
The turns ratio is greater than 1.
In modern imaging systems, the components for rectification are_______.
solid state semiconductors.
Low voltage ripple results in ________ radiation quantity and quality.
increased.
The x ray machine console allows you to control _____,_______ and _____.
- kV
- mAs
- focal spot size
The high voltage generator contains the _______ the ______ and the _______.
- high voltage transformer
- filament transformer
- rectifiers
_______ is a voltage waveform that results in 360 pulses per second after rectification.
Three phase.
What is the main goal for a mAs timer?
minimize the effects of patient motion.
What type of time can be used for rapid serial exposure and is very reproducible?
Electronic timer.
Voltage across the x ray tube is most constant with ______
High frequency generators.
_____ is measured by mA and _____is measured by mAs.
Current , charge.
the x ray generator with the lowest power rating is the _________imaging system.
single-phase.
The high voltage transformer has____
a turns ratio greater than one.
which of the following results in best utilization of the voltage waveform?
full wave rectified.
A step - down transformer is located in the _____ circuit.
filament
semiconductor reciters have two material types a p- type material with excess _____ and an n- type material with excess______.
holes, electrons.
The filament transformer ______.
increases the current.
The timer that operates based on a shaft rotating at a set speed is the _______ timer.
synchronous.
Voltage is______ related to the turns ratio.
directly
In full wave rectification, the wave applied across the x ray tube is always_______.
positive.
All the console controls are on the ______ side of the high voltage transformer and the ______side of the filament transformer
primary, primary
A single phase waveform has ____ripple.
100%
Ionization chambers are ________in AEC systems.
between the patient and the image receptor.
the kvp meter is located ________.
on the primary side of the high voltage transformer.
The _____ circuit provides electrons for the x ray tube current
filament.
In a semiconductor rectifier, when higher potential is placed on the P -side______.
there is Current flow through the diode.
Power to the primary side of the high voltage transformer comes from the _____.
secondary side of the autotransformer.
The inverter is the device that “chops” the waves into smaller shorter waves in a _______.
high frequency generator.
Current is _____ related to the turns ratio.
inversely
