X-Ray Physics (Part II) (Irene Gold) Flashcards
What three things are found inside the Cathode?
Large Filament
Small Filament
Focusing Cap
What is the source of the electrons that produce the x-ray?
Filament
What is the filament made out of?
Tungsten
When does a Thermionic Emission happen?
When current is applied to a filament
What controls the quantity of electrons (mA)?
Temperature of the filament
What part of the cathode encases the two filaments?
Focusing/Filament Cup
In what part of the Cathode does the Thermionic Emission occur?
Filament Cup
What is the name of the positive electrode in the x-ray tube?
Anode
In most x-ray machines is the anode stationary or rotating?
Rotating
What is the reason for a rotating Anode target?
To dissipate the heat that is generated
What is the focal area/spot of the Anode?
The exposed area of the tungsten target
How is the focal spot determined?
By the size of the filament
What does a Smaller filament produce as an outcome?
Better Detail
What is it called when “The effect of making the actual focal spot size appear smaller when viewed for the position on the film”?
Line Focus Principle
What give you a smaller effective spot on x-ray?
Smaller target angle
What is the term used that “Heats the filament causing a boiling off of electrons”?
Millamperage (mA)
How is the term Millamperage per Second defined (mAs)?
More Current=More Electrons produced= More x-ray produced= Greater Radiographic density (Darker)
What is the term used for overall blackening on the film?
Density
What does the term Radiolucent mean?
Structures produce more blackening on the film
What term is used for “Structures that produce less blackening on the film”?
Radio-opaque
Whiter on X-ray
The relationship between what two components of x-ray mAs and density?
They are directly proportional
What is the primary way to control how black a film is?
mAs
If the mAs is increased what does that mean in terms of film exposure?
The film exposure time is increased
What is the minimum change in mAs to see a change in density on the film?
30%
What does it mean to the density if the mAs is either doubled or halved?
The density will be doubled or halved, they are directionally proportional
What is the definition of Kilovoltage (kVp)?
The force applied to accelerate the electrons from the cathode to the anode at the time of exposure
When will the greatest number of high energy x-ray photons be produced?
When a great force of Kilovoltage (kVp) is produced
What is the relationship between wavelength and frequency?
Inversely related
If there is a low kVp what kind of energy and penetration are produced?
Low energy
Weak penetration
What kind of kVp would produce a high energy and a strong penetration?
High kVp
What kind of kVp produces shorter wavelengths with a greater ability to penetrate body tissue?
High kVp
What is the term that “is the difference in density between two structures”?
Contrast
What is the purpose of Contrast on an x-ray?
Makes detail visible
What is the relationship between kVp and contrast?
Inversely related
Does mAs or kVp control contrast?
kVP
In terms of Low kVp; what kind of contrast and scale are produced?
High Contrast=Short Scale
What kind of x-ray will be produced from a Low kVp setting?
Sharp difference in dark and light areas
A black and white film= underexposed (Bone Film)
Low kVp has what two effects?
Produces more scatter
Increased amount of radiation is absorbed by the patient
Low Contrast=Long Scale is seen in what kind of kVp film?
High kVp
What is expected to be seen on an x-ray film of High kVp?
Very little differences between densities
More shades of grey (Soft Tissue Film)
High kVp films have what two effects?
More scatter produced
Decreased amount of radiation is absorbed by the patient
How can you do the following on an x-ray film:
Lower Contrast
Longer Scale of Contrast
More Shades of Gray
Increase kVp by 15%
AND
Decrease mAs by 50%
How can you do the following on an x-ray film:
Higher Contrast
Shorter Scale of Contrast
Fewer shades of Grey (More Black and White)
Decrease kVp by 15%
AND
Increase mAs by 100%
What is the primary way to control density on an x-ray?
mAs
What is the relationship between kVp and density?
NOT proportional
What is the 15% Rule?
Increase the kVp by 15%=Double the film density
Decrease the kVp by 15%= Half the film density
Which tissue absorbs more x-ray?
Denser tissue
What two things are Black on x-ray?
Gas
Fat
What three things appear Gray on x-ray?
Muscle
Water
Soft tissue
What two things will show up as white on x-ray?
Bone
Metal
On which side of the x-ray is the intensity the greatest?
Cathode side
Towards what side do you place the thinner portion of the patient being x-rayed?
Anode Side (Anode Heel Effect)
Why is the thinner portion of the patient placed on the Anode Side of the x-ray tube?
Density and Intensity are Decreased
Which Side of the X-Ray machine produces less X-Ray?
Anode Side