Unit 5 Chapters 5&6 Flashcards
another name for the table
“the couch”
the couch used in fluoroscopy can tilt how many degrees towards the feet and how many degrees towards the head
90;30
the operating console should be where
behind a protective barrier
all x ray imaging systems contain what 3 things?
x-ray tube,operating console and high voltage generator
where do we select our kVp, mAs, or voltage and current
operating console
the number of x rays in the beam, we control this through the mAs
radiation quantity
the penetrability of the xray beam, we control this through the kVp (electric potential)
radiation quality
operating consoles will ____ have a control for kVp and for mAs
minimally
some consoles have a separate control for mA and time as well as ____ controls
AEC
most x ray imaging systems are designed to operate at __
220v
power companies do not provide us with 220V power accurately, it can vary how much
5%
measures the voltage and adjusts it to exactly 220V
provides consistency throughout the imaging system
line compensator
power is supplied first to the what?
autotransformer
controls voltage while it is at a low level while it is easier to control
the autotransformer
the autotransformer supplies precise power to the ___
filament circuit and the high voltage circuit (mA and kVp)
the autotransformer has how many windings?
one
the autotransformer has different ____& ____connections that determine the output
primary and secondary
the autotransformer can ___& ___the voltage
step up and step down
kVp determines the ______ of the x-ray beam, or the penetrability
quality
some older units allow selection of ___kVp and minor kVp which actually control 2 separate connections on the autotransformer
major
the kVp meter measures voltage not kilovoltage, but is registered as kilovoltage because the ____is known
turns ratio
on most operating consoles, a ____ kVp meter is used
pre-reading
the meter monitors the voltage before an ___ is made when the circuit has no current
exposure
the current travels from the autotransformer to the ___transformer
high-voltage
the current from ____to___ is measured in mA
cathode to anode
the temperature of the filament determines the number of electrons that are ___ and the number of x ray photons which will be ___
emitted; created
called thermionic emission
the ____circuit is separate from the kVp circuit, it has a separate connection on the autotransformer
filament
to control the mA station precisely, ____are added to the circuit to produce exactly 100mA, 200 mA, 300 mA, etc.
resistors
the filament transformer is what kind of transformer
step-down
the mA meter is in the x ray tube circuit on the __of the high voltage step up transformer
output
the AC current causes the center of the transformer to be ___volts ensuring safety
zero
A filament transformer steps down voltage to approx. how many volts
12v
with a filament transformer, the current is increased to approximately
5-8 amps
timers are used on the ____side of the high voltage transformer where voltage is lower
primary
prevent exposures from going on for longer than 6 seconds
guard timers
four types of timers
synchronous timers, electronic timers, mAs timers and Automatic Exposure Control (AEC)
most accurate timers
electronic timers
most exposure times are what kind?
electronic timers
measures the radiation reaching the image receptor and terminates when the desired radiation is reached
AEC
where is an ionization chamber placed
between the patient and the IR. this chamber is radiolucent so it will not be imaged
The three main parts of the x-ray imaging system are the x-ray tube, _____, and _____.
The three main parts of the x-ray imaging system are the x-ray tube, operating console, and high voltage generator.
The operating console contains circuits that are _____
The operating console contains circuits that are low voltage only.
Variations in power distribution to the x-ray machine are corrected by the _____.
variations in power distribution to the x-ray machine are corrected by the line voltage compensator
The first component to receive power in the x-ray circuit is the _____.
The first component in the x-ray circuit is the autotransformer.
The autotransformer has _____ winding(s).
The autotransformer has one winding.
The _____ circuit provides electrons for the x-ray tube current.
The filament circuit provides electrons for the x-ray tube current.
Thermionic emission at the filament determines the _____ across the x-ray tube during an exposure.
Thermionic emission at the filament determines the milliamperage across the x-ray tube during an exposure.
A step-down transformer is located in the _____ circuit.
A step-down transformer is located in the filament circuit.
The most accurate type of timer is the _____ timer.
The most accurate type of timer is the electronic timer.
The automatic exposure control (AEC) terminates the exposure when _____.
The automatic exposure control (AEC) terminates the exposure when sufficient radiation reaches the image receptor.
The mAs timer is usually set to give the _____ mA at the _____ time.
The mAs timer is usually set to give the highest mA at the shortest time.
A diode allows electrons to flow from _____.
A diode allows electrons to flow from cathode to anode.
The difference in the waveform between the primary and secondary sides of the high voltage transformer is _____.
The difference in the waveform between the primary and secondary sides of the high voltage transformer is amplitude.
In modern imaging systems, the components for rectification are _____.
solid state semiconductors.
With half-wave rectification, the current flows through the x-ray tube during the _____ part of the cycle.
positive part
Full-wave rectified, three-phase units provide an x-ray beam at _____ pulse(es) per second.
Full-wave rectified, three-phase units provide an x-ray beam at 360 pulses per second.
Voltage across the x-ray tube is most constant with _____.
Voltage across the x-ray tube is most constant with high frequency generators.
A single-phase waveform has _____ ripple.
A single-phase waveform has 100% ripple
What is the industry standard formula for calculating high voltage generator power?
The industry standard for calculating high voltage generator power is to use the maximum tube current at 100 kVp and 100 ms.
The x-ray generator with the lowest power rating is the _____ imaging system.
The x-ray generator with the lowest power rating is the single-phase imaging system.
The most widely used support structure for the x-ray tube is the _____.
The most widely used support structure for the x-ray tube is the ceiling support system.
The external structure of the x-ray tube includes the support structure, the protective housing, and the _____.
The external structure of the x-ray tube includes the support structure, the protective housing, and the glass envelope.
As an x-ray tube ages, the inside can become coated with tungsten, which can cause _____ in the tube.
Tungsten coating within the tube can cause arcing
The negative side of the x-ray tube holds the _____.
The negative side of the x-ray tube holds the filament
What is the most common cause of tube failure?
The most common cause of tube failure is tungsten vaporization.
The filament is made of _____.
tungsten.
Thermionic emission at the filament creates a _____.
Thermionic emission at the filament creates a space charge.
The rotating anode is turned by a _____.
The induction motor works by electromagnetic induction.
When electrons bombard the target, _____% of their kinetic energy is converted to heat
When electrons bombard the target, 99% of their kinetic energy is converted to heat.
The _____ is the source of radiation in the x-ray tube.
The focal spot is the source of radiation in the x-ray tube.
Because of the line focus principal, the effective focal spot size decreases with decreasing _____.
The size of the effective focal spot decreases as the target angle decreases.
The x-ray intensity is lower on the anode side of the tube because of the _____.
The heel effect causes x-ray intensity to be greater on the anode side of the tube.
The cathode side of the tube should be directed toward the _____ part of the patient.
The cathode side of the tube should be directed toward the thicker part of the patient, because of the heel effect.
The filament in an x-ray tube is about _____ cm in length.
The filament in an x-ray tube is about 1-2 cm in length.
A dual focus tube has two _____.
The dual focus tube has two filaments
Each tube has its own tube rating chart to show _____.
Each tube has its own tube rating chart to show maximum exposure times.
The _____ is/are outside the glass envelope.
The stators are outside the glass envelope.
Extrafocal or off-focus radiation is produced from _____.
Extrafocal or off-focus radiation is produced from rebounding electrons.
The effective focal spot size is _____ the actual focal spot size.
The effective focal spot size is smaller than the actual focal spot size.
Localized pitting or cracking on the anode can occur from _____.
Localized pitting on the anode target can occur from a single excessive exposure.
All of the following are radiographer-operated controls EXCEPT
rotor speed
Radiographic rooms equipped with a tilting table are primarily designed for performing ____ procedures.
fluoroscopic
All of the following are x-ray tube support systems EXCEPT
C-arm.
floor-to-ceiling.
overhead suspension.
fluoroscopic tower.
fluoroscopic tower.
Which tube suspension system offers the greatest multidirectional movement?
overhead tube suspension system
A filament may break due to
vaporization.
The focusing cup has a/an ____ charge.
negative
As more and more electrons build up in the area of the filament, their negative charges oppose the emission of additional electrons. This phenomenon is known as
space charge effect
X-ray photon production occurs at the
anode
The exact point on the anode where the x-ray beam emanates is the
focal spot
Which side of the x-ray tube will produce lense density on a finished radiograph?
anode
As the actual focal spot size increases, the effective focal spot size
increases
The function of the stator and rotor assembly is to
rotate the anode
The protective housing controls leakage and scatter radiation through
absorption
What type of radiation is composed of photons not produced at the actual focal spot?
off focus and extrafocal
To determine the allowable combination of exposures factors, thus preventing x-ray tube damage,
an x-ray tube rating chart is checked prior to exposure
