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ChiroBoards2:XrayPhy

ChiroBoards2: Xray Physics/Production

QuestionAnswer
xray tube inside a protective housing made of __________? lead
xray tube consists of two electrodes called the ___________ and _________? Cathode and Anode
This consists of a large filament, small filament and a focusing cup Cathode
serves as a source of electrons in the production of xrays filaments
filament is made from tungsten
Occurs when a current is applied to the filament Thermionic Emission
What controls the quantity of electrons (mA) emitted from the filament? temperature
What does the number of electrons determine? the number of x-rays created
What determines mA? Temperature
Where does thermionic emission occur within? the focusing cup/filament cup
The positive electrode in the xray tube the anode
what is more common; stationary or rotating anode? rotating anode
why does the anode rotate? to dissipate the heat generated
exposed area of the tungsten target on the anode focal spot
what determines the focal spot? size of the filament
smaller filament = __________ detail: better/worse? better detail
Beam Hardening aka Line focus principle
Beam Hardening: smaller the target angle, the _____________ the effective spot smaller
Stream of electrons narrows down to an effective beam Beam hardening
mA = Milliamperage
Heats the filament causing a boiling off of electrons Milliamperage
More Current = ____________ radiographic density : More or Less? MORE
Overall blackening on film: relates to? density
structures that produce more blackening on the film Radiolucent (more black)
structures that produce less blackening on the film Radio-opaque (more white)
MAS and Density: what type of relationship? Directly proportional
How to change blackness on a film? Change the MAS
Increased MAS = More film exposure / darker
% of minimum change needed to see a minimum change in density on the film. 30%
If mAs is doubled, the density is_______________ doubled
the force applied to accelerate the electrons from the cathode to anode at the time of exposure. Kilovoltage (kVp)
Wavelength and frequency: what type of relationship? inverse relationship
low kVp =__________ energy= ____________ penetration low energy; weak penetration
high kVp = __________ energy= ___________ penetration high energy; strong penetration
Difference in density between two structures contrast
kVp and Contrast: what type of relationship? kVp controls contrast, but they are inversely related.
low kvp = _______ contrast high contrast
High contrast = short scale (low or high kvp?) low kvp
sharp differences in dark and light area; "black and white" film = low or high kvp? low kvp
Good for bone film: low or high kvp? low kvp
less scatter but more patient absorption: w/ higher or lower kvp lower kvp
high kvp = ______ contrast low contrast
low contrast = long scale (low or high kvp?) high kvp
more shades of grey (soft tissue film) = low or high kvp? high kvp
produces more scatter but less patient radiation absorption : low or high kvp? high kvp
15% rule = To lower contrast = Increase kvp by 15%, and decrease MAS by 50%
15% rule = To increase contrast = Decrease kvp by 15% and increase MAS by 50%
How is density affected by the 15% rule? increase in kVp will double overall density on film and decrease in kVp will cut density in half.
Denser tissue absorbs _______ x-rays, while less dense tissues transmits _______ x-rays. (more or less?) more; more
Gas = density? black
Fat = density? black
Muscle, water, and soft tissue = density? gray
Bone and metal = density? white
This effect given because the rotating target is angled, thus producing a varied intensity. Anode Heel Effect
Intensity of x-ray is greater on the _________ side when compared to the _________ side. (anode or cathode?_ cathode ; anode
Because of the Anode heel effect, when x-raying a foot, would you aim the x-ray tube so the cathode was pointed at the toes or ankle? and why? ankle, because it's thicker
Because of the Anode heel effect, when x-raying a foot, would you aim the x-ray tube so the anode was pointed at the toes or ankle? and why? Toes, because it's thinner
Anode Heel Effect: Anode side = less or more x-ray? less x-ray
Anode Heel Effect: Cathode side = less or more x-ray? more x-ray
Anode Heel Effect: Anode side = smaller or larger effective focal spot? smaller focal spot
Anode Heel Effect: Cathode side = smaller or larger effective focal spot? larger focal spot
Anode Heel Effect: Anode side = more or less detail? more detail
Anode Heel Effect: Cathode side = more or less detail? less detail
Anode Heel Effect: Anode side = use thinner or thicker body part? Thinner
Anode Heel Effect: Cathode side = use thinner or thicker body part? Thicker
Increase FFD = ________ Detail (increased or decreased?) increased
Focal film distance, aka? Source Image Distance
FFD represents what? length of space from the focal spot (or tube) to the recording medium (or film)
As you __________ the FFD, the image gets smaller and more clear. (increase or decrease?) Increase
As you _________ the FFD, the image gets larger and blurrier. (increase or decrease?) Decrease
Intesity of radiation varies inversely with the square of the distance from the source. = what law? Inverse square law
If a 40 inch FFD is doubled to an 80 inch FFD, the intesity of the radiation is _______ the amount of the intensity at 30 inches. one quarter the amount
If a 40 inch FFD is increased to 80 inches FFD, how much must the radiographer increase (or decrease) MAs in order to maintain the same amount of film blackening Increase MAs 4x
Double the Distance = __________ the radiation (amount?) one fourth the radiation
Half the Distance = ________ the radiation 4x the radiation
What piece is hit by the x-ray, causing fluorescent salts to change x-ray photons into visible light photons? Intensifying Screen
What does the Intensifying Screen do to help the patient? Exposes the film and decreases patient exposure
Large Crystals (more light) works quickly and yields _________ detail. (more or less?) less detail
Faster screens = _________ contrast = ___________ scale Higher contrast ; Short Scale (less patient exposure)
Small Crystals (less light) works slowly and yields _________ detail. (more or less?) more detail
Slow screens = _________ contrast = ___________ scale Lower contrast; Long Scale (more patient exposure)
Intensifying screens ________ density on the film (increase or decrease?) increases density
Picture made by the useful beam Umbra
Blurry halo parts of the image (unsharpness) Penumbra
This is caused by having the tube too close to the film (Short FFD) Penumbra
This is caused by having the patient too far from the film (long OFD) Penumbra
This is caused by having too big a filament on the cathode, making the focal spot too big Penumbra
Penumbra is caused by 3 things: Too short a FFD; Too long an OFD ; Too big a filament on the cathode
OFD stands for Object Fim Distance
Distance between patient and film is called Object Film Distance (OFD)
Increase OFD = (does what to the image?) makes it bigger and blurrier (more penumbra)
Decreased OFD = (does what to the image?) makes it smaller and more clear (better detail)
The pressure exerted by the film holder as it encloses the x-ray film = Screen Fim Contact
Best test for screen film contact = The wire-mesh test
Poor screen film contact does what to the image? reduces its sharpness
Two types of distortion = Size and Magnification
What types of radiation occurs when x-rays strike an object? (3) Scattered, Absorbed, or Penetrated
Scatter radiation can be reduced by using one of the following = (4) things Grids; Air Gap Technique; Collimators; Filters
A device of alternating strips of lead and spacer material Grid
Grids are placed between what two objects? the Patient and the Film
How does the grid improve the quality of the radiograph? absorbs scatter radiation
When using a grid, what must be increased to maintain density? Exposure factors
Explain Grid Ratio = The height of the lead strips : to the distance between the strips
What is the grid ratio in a chiropractic office** ? 12:1
What is the air gap distance between the patient and the film? 6-10 " (example = lateral cervical view)
The distance between the body part and the film causes scatter radiation to diverge away from the film. What is this technique called? Air-Gap Techinque
Limits the size of the bean to the size of the body part you need to capture on film = Collimation
What is the best way to reduce scatter radiation to the patient, as well as to the film? use collimation
this process is the preferential removal of low energy photons = Filtration
Filtrators are usually made of = Aluminum
Used to identify irradiation of patients and measures the radiation energy absorbed = Radiation Absorbed Dose (RAD)
This unit is typically applied to occupationally exposed persons Radiation Equivalent Man (REM)
How is REM measured on radiation workers? by a photosensitive badge worn on the collar
1 RAD = ____ REM 1 REM
The number of REMs a person can get a lifetime without getting radiation poisoning = Maximum Permissible Dose (MPD)
What is the safe REM (or RAD) amount to have per year? 5 REMS (RADS)
Bremsstrahung aka? Braking Radiation
Majority of useful beam and interacts with the target nucleus = (type of radiation?) Bremsstrauhlung Radiation
A high intensity electron hits an inner shell electron which is knocked out of position in orbit. An out shell then fills its spot. = (type of radiation?) Bremstrauhlung radiation
Primary form of scatter = (type of scatter radiation) Compton Scatter
a moderate energy x-ray knocks out an outer shell electron which causes a loss of energy = (type of scatter radiation?) Compton Scatter
Classic Scatter, aka's (2)? Thompson Scatter ; Coherent Scatter
A low energy x-ray that changes direction with no energy loss and contributes to film fog = (type of scatter radiation?) Classic Scatter
A low energy photon is absorbed by the subject creating a latent image on the film = Photoelectric effect
Quantum Mottle, aka? Radiographic Noise
Faster screens produce _________ quantum mottle = (more or less?) more quantum mottle
What will decrease radiographic noise in regards to altering MAS and KVP? High MAS and low KVP will decrease radiographic noise
This is caused by having too big a filament on the cathode, making the focal spot too big Penumbra
Penumbra is caused by 3 things: Too short a FFD; Too long an OFD ; Too big a filament on the cathode
OFD stands for Object Fim Distance
Distance between patient and film is called Object Film Distance (OFD)
Increase OFD = (does what to the image?) makes it bigger and blurrier (more penumbra)
Decreased OFD = (does what to the image?) makes it smaller and more clear (better detail)
The pressure exerted by the film holder as it encloses the x-ray film = Screen Fim Contact
Best test for screen film contact = The wire-mesh test
Poor screen film contact does what to the image? reduces its sharpness
Two types of distortion = Size and Magnification
What types of radiation occurs when x-rays strike an object? (3) Scattered, Absorbed, or Penetrated
Scatter radiation can be reduced by using one of the following = (4) things Grids; Air Gap Technique; Collimators; Filters
A device of alternating strips of lead and spacer material Grid
Grids are placed between what two objects? the Patient and the Film
How does the grid improve the quality of the radiograph? absorbs scatter radiation
When using a grid, what must be increased to maintain density? Exposure factors
Explain Grid Ratio = The height of the lead strips : to the distance between the strips
What is the grid ratio in a chiropractic office** ? 12:1
What is the air gap distance between the patient and the film? 6-10 " (example = lateral cervical view)
The distance between the body part and the film causes scatter radiation to diverge away from the film. What is this technique called? Air-Gap Techinque
Limits the size of the bean to the size of the body part you need to capture on film = Collimation
What is the best way to reduce scatter radiation to the patient, as well as to the film? use collimation
this process is the preferential removal of low energy photons = Filtration
Filtrators are usually made of = Aluminum
Used to identify irradiation of patients and measures the radiation energy absorbed = Radiation Absorbed Dose (RAD)
This unit is typically applied to occupationally exposed persons Radiation Equivalent Man (REM)
How is REM measured on radiation workers? by a photosensitive badge worn on the collar
1 RAD = ____ REM 1 REM
The number of REMs a person can get a lifetime without getting radiation poisoning = Maximum Permissible Dose (MPD)
What is the safe REM (or RAD) amount to have per year? 5 REMS (RADS)
Bremsstrahung aka? Braking Radiation
Majority of useful beam and interacts with the target nucleus = (type of radiation?) Bremsstrauhlung Radiation
A high intensity electron hits an inner shell electron which is knocked out of position in orbit. An out shell then fills its spot. = (type of radiation?) Bremstrauhlung radiation
Primary form of scatter = (type of scatter radiation) Compton Scatter
a moderate energy x-ray knocks out an outer shell electron which causes a loss of energy = (type of scatter radiation?) Compton Scatter
Classic Scatter, aka's (2)? Thompson Scatter ; Coherent Scatter
A low energy x-ray that changes direction with no energy loss and contributes to film fog = (type of scatter radiation?) Classic Scatter
A low energy photon is absorbed by the subject creating a latent image on the film = Photoelectric effect
Quantum Mottle, aka? Radiographic Noise
Faster screens produce _________ quantum mottle = (more or less?) more quantum mottle
What will decrease radiographic noise in regards to altering MAS and KVP? High MAS and low KVP will decrease radiographic noise
Solution temps that are too hot will _________ density = (decrease or increase?) increase
What processing factor brings out LATENT IMAGE by developing the exposed silver halide crystals? Developer
Reducer/Developer = function? Produces shades of gray and black
Reducer/Developer = chemicals? Phenidone/ Hydroquinone
Accelerator/ Activator = function? swelling of emulsion
Accelerator/Activator = chemicals? NA+ carbonate
Preservative = function? controls oxidation
Preservative = chemicals? Na+ sulfite or K sulfite
Restrainer = function? protects unexposed crystals
Restrainer = chemicals? Potassium Bromide/Iodine
Hardener = functions? controls swelling of emulsion
Hardener = chemicals? Glutaraldehyde
What does Rinse do? (processing factor) rinses away the exposed silver halide crystals
What does the Fixer do? (processing factor) hardens the image, making it permanent on the film
FIXER = Acidifier/Activator = function? Neutralizes the developer/ "stop bath"
FIXER = Acidifier/Activator = chemical? Acetic Acid
FIXER = Clearing Agent = function? Removes undeveloped Ag Halide/ "Hypo Solution"
FIXER = Clearing Agent = chemical? Ammonium
FIXER = Hardener = function? stiffens/ shrinks the emulsion
FIXER = Hardener = chemical? Potassium Alum
FIXER = Preservative = function? Maintains pH of fixer
FIXER = Preservative = chemical? Sodium Sulfate
Washing does what? Removes developer and fixer
What results from a film that has "Light Leak"? Dark films
What results from a film with a developer temperature that is too hot? Dark films
What results if a film is over exposed (too dark or too light?) Dark films
What results if a film has developer temperature that is too low? Light films
What results if a film is taken while the chemicals need replacing at the same time? Light films
These color films result with inadequate developer = Brown films
These types of films occur with inadequate fixer = Milky films
These types of films occur with insufficient washing = Greasy films
This can occur if you have an old film, hot developer, and contaminated chemicals = increased fog
This is seen on the film if there is insufficient fixing = soft emulsion
Store the film/cassette __________ to avoid pressure damage. = (vertically or horizontally?) Vertically
This is produced when removing the film quickly from the cassette. Static Electricity
What can static electricity do to a film when it is being removed from the cassette? can cause black and branching lightning-like lines on the film
What does a rectifier do? Changes AC to DC
What does a transformer do? Steps up or steps down the power
What does a transducer do? Changes one form of energy to another
What is the term used when a beam of radiation loses energy as it passes thru matter? Attenuation
Why is blue or green tint added to the base of the x-ray film? To reduce glare
Nail marks on fim appears as _________ : creases
Created by: bglasman on 2012-02-29



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