Imaging Chapter 1 Flashcards
What is a Latent Image?
An image before processing
What is a Manifest Image?
The image seen after processing
What is an IR?
A device that receives the energy of the x-ray beam and forms the image of the body part
The protective housing is ____ and _____ the x-ray tube.
Lead Lined; encases
What is the purpose of the protective housing?
To provide mechanical support and protection from damage
To protect user from shock
Why do some tube housing contain oil?
To provide more insulation and a thermal cushion
What is the tube made of?
Pyrex glass
What is the housing designed to do?
limit the beam to exit through the window
Define off-focus radiation:
Radiation that occurs when x-rays are produced OUTSIDE focal spot
Define leakage radiation:
X-rays other than primary beam that escapes the tube housing
The Xray tube envelope can be made of ___ or ___.
Glass; metal
Why are x-ray tubes made of metal?
Metal can handle more heat
Metal reduces off-focus radiation
Why are x-ray tubes made of metal?
Metal can handle more heat
Metal reduces off-focus radiation
How big is the window/port?
5 cm
What does a glass envelope allow?
It allows ALL air to be removed for more efficient flow of electrons from cathode to anode
The whole cathode and anode must be encased within a ____?
Vacuum
An x-ray tube that contains two charged electrodes is called a :
Diode tube
the cathode is ____ charged.
Negatively
What are the two parts of the cathode?
Filament
Focusing cup
What is the filament made of?
Tungsten
What is the size range of the filament?
0.1 to 0.2 mm thick
1 to 2 mm wide
7 to 15 mm long
What is a tube with TWO filaments called?
Dual-focus tube
Which size focal spot gives better recorded detail?
Small
What is the focusing cup made of?
Nickel
What is the purpose of the focusing cup?
To focus the stream of electrons
The anode is ____ charged?
Positively
What is apart of the anode?
Anode(target)
Stator
Rotor
What is the purpose of the anode target?
To decelerate and stop electrons in the tube current allowing the production of x-rays
Where is the stator?
Outside of the tube
What is the rotor made of?
Copper
What is the target angle range?
5 to 20 degrees
What is the purpose of the anode angle?
To help the x-ray photons exit the tube
What type of interactions are produced in the anode?
brem
Characteristic
Brems Interactions diagnostic range:
30 to 150 kVp
In diagnostic imaging most interactions are _____:
Brem
Less than ___ kVp and ___% of x-ray beam consists of Brem interactions
70 kvp
100%
The only part of the X-ray tube that is located outside of the Pyrex glass is:
The stator
As wavelength of an xray increases, what happens to its frequency?
It decreases
What is the minimum rotation speed of the Anode?
3000 RPM
What interaction composes 100% of the x-ray tube beam if 70 kVp is used?
Brem
X-rays are classified as what type of radiation?
Electromagnetic
Biological changes caused by x-rays are the result of :
Ionization
______ Interactions cannot be produced at less than 70 kVp.
Characteristic
What is the distance between two wave crests of an electromagnetic wave called?
Wavelength
Above 70 kVp, ___ % are characteristic interactions.
15%
Below _____ kvp, there are no characteristic interactions.
70
Kilovoltage determines:
The speed of the electrons in the tube current
Miliamperage determines:
The number of electrons flowing per unit time
Exposure time and x-ray quantity are _____ proportional
Directly
What is exposure time?
The length of time x-rays are produced
Increasing exposure time, will ______ the total number of x-rays produced
Increase
What are the prime exposure factors?
Kilovoltage
Miliamperage
exposure time
As electrons strike the anode target, about ___% of the kinetic energy is converted into heat and ___ % is converted into x-rays.
99%
1%
What do generators do?
Convert low voltage to high voltage (kilovolts)
What are the three basic generators?
Single-phase
Three-phase (6-12 pulses per cycle)
High Frequency
What is the voltage range and voltage ripple for a single-phase generator?
Voltage range: peak to 0
Voltage ripple: 100%
What is the voltage ripple for a 6-pulse Three-phase generator?
13%
What is the voltage ripple for a 12-pulse three-phase generator?
4%
What is the most consistent type of generator?
High-frequency
What is the voltage ripple of a high-frequency generator?
Less than 1%
The most consistent the voltage applied to the tube, the ______ the quantity and energy level of the beam.
Greater
What is the meaning of beam quality?
The penetrability of an xray beam
High quality beams produce:
Harder xrays that penetrate more
Lower quality beams produce:
Softer xrays that penetrate less
What does the quantity of beam mean?
The number of photons in the beam
kVp affects:
Both quantity and quality
Higher kVp will produce _____ scatter radiation.
More
Why does kVp have more effect on any other exposure factor?
It affects beam quality and quantity
What is the main controlling factor of contrast?
KVp
What does mA determine?
The tube current
What is tube current?
The number of electrons flowing per unit time between cathode and anode
What does mA determine?
The number of electrons flowing in the tube and the quantity of x-rays produced
mA and quantity of electrons in tube current are ______ proportional.
Directly
What is the ONLY thing mA controls on a radiograph?
Density
Longer the exposure time, the ______ the quantity of electrons will flow
Greater
Time and mA are multiplied together to form:
mAs
What does mAs represent?
The total number of x-rays produced in a beam
An increase in mAs results in a ____ of density on a radiograph
Increase
a decrease in mAs results in a ______ in density on the radiograph.
Decrease
mAs and density are _____ proportional
Directly
mA x time =
mAs
mAs/s =
mA
mAs/mA=
S
The density produced on the radiograph will be equal for any combination of miliamperage and exposure time (mAs), as long as the product of mAs is equal.
Law of Reciprocity
Where the electrons actually bombard the target
Actual focal spot
Focal spot size as measured directly under the anode target
Effective focal spot size
The smaller the anode angle, the _____ the effective focal spot size
Smaller
Smaller effective focal spot size produces:
Better image quality
X-ray beam has a greater intensity (number of x-rays) on the _____ side
Cathode
There is a ____% difference in intensities
45
The Cathode end is placed over the ____ part to even out the density of a radiograph.
Thicker
the decrease of anode angle will _____ the anode heel effect. Therefore making an ____ relationship.
Increase; inverse
There are two types of total filtration. What are they?
Inherent
Added
What type of filtration is added to the port of the x-ray tube?
Added
What type of filtration is permanently in the path of the x-ray beam?
Inherent
The sum of the added filtration and the inherent filtration:
Total filtration
Aluminum is a type of _____ filtration?
Added
The glass envelope, oil surrounding the tube, the mirror inside, and the collimators are all examples of what type of filtration?
Inherent
What is the government standard of total filtration?
Above 70 kVP minimum filtration of 2.5 mm of aluminum
What is the half-value layer(HVL)
The thickness of absorbing material necessary to reduce the x-ray intensity to half of its original value
HVL is expressed in:
Millimeter of aluminum (mm-Al)
What are compensating filters used for?
To alter beam intensity
What are two types of compensating filters?
Wedge and trough
What is the formula used to find heat units(HU)?
HU=mA x time x kVp x generator factor
What is the generator factor for a single phase generator?
1.00
What is the generator factor for a three phase generator?
1.35
What is the generator factor for a high frequency generator?
1.40
