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248 Cards in this Set
- Front
- Back
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propagation of energy through space as oscillating electromagnetic fields
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electromagnetic radiation
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T/F: em radiation has charge but no mass and travels at the speed of light.
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false
em radiation has NO charge |
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x rays, gamma rays, and uv rays have the same _____ consistency.
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physical
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T/F: all em radiation travels at the same speed.
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true
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Electromagnetic radiation varies in ___ and ___ , but not in the speed.
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wavelength
frequency |
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What is the relationship between wavelength and energy of EM?
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inverse
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What are the types of ionizing radiation?
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x rays
uv rays g rays |
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____ radiation has enough energy to cause ionization of the medium thru which they pass
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ionizing
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gamma rays originate from:
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WITHIN the nucleus of spontaneously DECAYING atoms
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X rays originate from:
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OUTSIDE the nucleus by INTERACTION of high speed particles
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X rays are produced by interaction of high speed ___.
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electrons
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What are the three basic principles of X ray production (you need this this and this).
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-SOURCE of electrons
-method of ACCELERATION of those electrons to a high speed -INTERACTION of those electrons with a target |
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____ is needed to pull electrons across filament toward the target.
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Voltage
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____ is a thin coiled wire that serves as the source of electrons.
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Filament
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What is filament made of? Why?
Is it part of the anode or cathode? |
Tungsten
- provides a large number of electrons and withstands high temperatures -cathode |
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What is the process of electron production called?
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thermionic emission
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Forcing current thru the resistance of the filament creates ___ while producing ____ in a cloud around the filament.
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Heat
electrons |
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The filament is recessed in a negatively charged ______ that keeps the electron cloud from dispersing.
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focusing cup
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How are electrons accelerated?
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a high potential difference (VOLTAGE) is applied across the tube to pull and accelerate electrons from the filament across the tube, toward the target.
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The ___ part of the tube contains the Target and is thus ___ charged.
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anode
positive |
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___ is a small area where INTERACTION actually takes place on the target.
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Focal spot
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What is the "tube" made of?
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glass
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What is unique about the environment of the tube?
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vacuum-- to prevent incidenta interaction of the electron beam with air atoms
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X rays go in all directions, but we use ___ housing to direct the "useful" beams.
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LEAD
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What does isotropic mean in relation to xray production?
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xrays are emitted in all directions
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What are the two processes by which electron interaction can produce xrays?
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transition (characteristic)
bremsstrahlung (general) |
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T/F: xrays are all the same specific energy.
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False
they cover a spectrum of energies |
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T/F: the process of xray production is relatively efficient.
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FALSE
*inefficient |
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Why is xray production so inefficient?
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-EXCITATION- of target atoms rather than xray production
- Bremsstrahlung- em radiation is belos the xray energy range |
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99% of incoming electron energy is converted to ___
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heat.
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____% of incoming electron energy is converted to x rays
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1%
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What is the MAJOR limiting factor of xray production, tube design and construction, and tube use?
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HEAT
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What is the difference between the actual focal spot and the effective focal spot?
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actual: physical dimension
effective: apparent size of the focal spot as viewed by the patient |
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a (larger/smaller) apparent focal spot ENHANCES detail.
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Smaller
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a ___ angle of the target allows for a smaller apparent focal spot which also enhances detail.
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steeper
*steepness of the angle limits xray output due to excessive target self absorption of the primary beam |
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Increasing the focal spot (increases or decreases) heat dissipation.
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increases
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What is the importance of the anode design?
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relates output capabilities of the tube and cost of the equipment
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What are the limits of a staionary anode?
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limited HEAT DISSIPATION limits XRAY output
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What are the advantages of a stationary anode?
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it is highly portable
radiation therapy |
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Describe a rotating anode.
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high speed rotating discs
filament offset and aimed at the periphery of the disc (interaction is spread over a large surface area) |
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what are the benefits of rotating anodes?
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Very good HEAT dissipation
allows for greater xray output |
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What are the disadvantages of rotating anodes?
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NOT portable
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Why do rotating anodes generally have TWO filaments?
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allows for the generation of a small and large focal spot.
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a ___ focal spot is used for most routine work.
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LARGE
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Small focal spots generally have very limited ____.
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output
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What 2 quantities of the xray beam are significant and controllable?
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quantity-- #
quality-- energy |
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Quality of xrays refers to ___.
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Energy of xrays
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Penetrability of xrays is proportional to ___.
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energy
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Tube voltage is measured in ____ which is controlled via the ____.
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kVp
kVp selector on the control panel |
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what determines the number of xrays in a beam?
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the number of electron interactions with the target
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___ increases when you increase kVp which therefore increases the energy of the electrons traversing the tube.
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voltage
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how do you increase the energy of the x rays?
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increase kVp
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# of interactions per electron is determined by ___ which is controlled by ___.
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energy
kVp |
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# of electrons emitted is determined by current thru the ____ which is controlled by____ in addition to the lenght of time of exposure.
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filament
mA selector |
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kVp selector controls the _______ of the high voltage across the tube.
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peak magnitude
*affects energy of e- and xrays and interaction and therefore number of xrays |
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mAs is a very important concept that refers to the _____ of xrays withing a beam.
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quantity
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Exposure timers control the time that the _____ is applied to the tube. this controls the time that electrons flow across the tube which controls the number of ____________ and therefore the number of xrays produced.
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high voltage
electron interactions |
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a higher mA will require a (decreased/increased) exposure time.
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decreased
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mAs controls the _____ or intensity of the beam
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quantity
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kVp primariily controls the _____ of the beam but may also affect ___.
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quality
*some quantity |
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300 mA x 1/60 sec
and 200 mA x 1/20 sec do they produce the same number of xrays? |
yes
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increasing mAs increases the number of xrays but not _____.
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energy
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increasing energy increases ____ of xrays.
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number
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what happens if you "overload" the tube? How is this prevented by modern machinery?
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the target melts
newer xray machines have built in target loading charts with a set maximum that will prevent overloading |
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x rays are a type of ___ radiation which is a propagation of ___ through space as oscilating ____.
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electromagnetic
energy electromagnetic fields |
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how do xrays differ from gamma rays? how are they the same?
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same: speed (C)
differ: origin gamma rays comes from within the nucleus due to decaying atoms xrays come from outside the nucleus due to particle interaction |
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what are the basic components of an xray tube?
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target-- interaction
filament--- source glass tube voltage-- acceleration |
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What limits the production of xrays in an xray tube?
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focal spot
heat dissipation (rotating vs stationary) |
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what are the physical differences between stationary anode and rotating anode xray tubes? Advantages and disadvantages?
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stationary: small fixed target=
portable less resolution 1 filament: large focal spot rotating: large rotating disc increased heat dissapation 2 filaments: large and small focal spot |
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How are xray beams characterized?
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Quantity: #
Quality: energy |
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What is mAs and what does it conrol?
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current through the filament--> # of electrons
Overall effect is on QUANTITY |
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What is kVp and what does it control?
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energy of the elecetrons--> particle interaction
overall effect is on QUALITY |
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What does a radiographic filter consist of?
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x ray absorbing material in the path of the xray beam
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what are the 2 classes of filtration?
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inherent
and added |
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____ is filtration by theglass in the xray tube and the surrounding oil.
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inherent
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total filtration of the beam includes the ____ and the ____.
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inherent and added filtration
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the use of filters produces a cleaner image by absorbing _______ that tend to scatter more.
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low energy xray photons
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A collimator is used to ___.
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restrict the xray beam to a confined region
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Where is a collimator located?
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outside the tube housing
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Proper collimation of the xray beam reduced patient exposure by ______.
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reducing the volume of tissue irradiated
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Proper collimation improves image ____.
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image contrast
*by reducing scatter radiation |
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Where is the grid usually located?
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below the table top, above the film
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Scatter radiation is the result of ____ interactions of xrays with matter.
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Compton
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any tissue greater than ___ (measurement) should be imaged using a grid.
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10cm
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Grids are composed of hundreds of alternating strips of ___ and ___.
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lead and aluminum
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The lead strips in a focused grid are angled to be in alignment with _____.
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the divergent path of the xray photons leaving the focal spot
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the total number of xray photons that reach the film is (greater, less) than without the grid, and therefore (more, less) xrays are needed when using a grid.
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less (grids reduce # xrays)
more |
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Why is grid alignment so important?
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the strips are meant to be aligned perpendicular in the center and more angular toward the periphery in order to line up with the xray beam
- misalignment will distort the image |
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a ___ ratio grid is more effective than a ___ ratio grid in cleaning up scatter radiation
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high is more effective than low
(grid is taller = cleans up more scatter radiation) |
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Using a grid "lightens" the film and so exposure must be (decreased/increased)
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increased
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A cassette is a rigid, light-tight device that holds the xray film in contact with the ____.
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intensifying screen
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What is the function of the screen?
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convert xrays to visible light
*it is the light that exposes the film |
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Screens convert xrays to visible light to expose the film. this is more efficient than exposing the film only to xrays. Why is this important?
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the net result is a reduction in the amount of radiation needed to make an exposure
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Where are screens located?
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inside the cover of the cassette
must be in contact with the film |
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T/F: most cassettes have 2 screens.
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True
*one for each side of the film |
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List the layers of a loaded cassette in the proper position.
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cassette (tube side)
screen film screen lead (within cassette layer) cassette |
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How does the screen cause a reduction in the sharpness of the image?
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thicker phosphor layers cause diffusion of light prior to it reaching the film
* there is less light spread and therefore greater image detail with thinner phosphor layers |
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What are the ratio percentages of xray and light that result from the use of a screen?
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99% light
1% xray |
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T/F: detail and sensitivity are directly related, meaning that as the sensitivity of the screen increases the detail of the image increases.
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FALSE
detail and sensitivity are INVERSELY related |
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concerning films, detail refers to sharpness while sensitivity refers to __.
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the amount of radiation required to adequately expose the film
*high detail screens require larger amounts of radiation to get adequate exposure BECAUUUUSE high detail screens have thinner phosphor layers--> less light spread<-- requires MORE xrays to expose the film |
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sensitivity increases with _____ speed screens and detail _____.
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increased (faster) speed
decreased detail |
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how do u determine the mAs if you are changing screen speeds?(formula)
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mAs1 x speed1 = mAs2 x speed 2
algepbraically adjusted: new mAs = original mAs x original speed/ new speed |
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T/F: a single screen cassette and a single emulsion film will generally require ______ the exposure as a double screened cassette and double emulsion film.
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double
*advantage = better detail with single screen single emulsion |
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How does the emulsion and the screen on the "under" side of the film get exposed?
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light spread continues through the film base to expose the deep layers
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What is the term for matching the film sensitivity to the color emitted by the screens?
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spectral matching
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What is emulsion made of?
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gelatin material embedded within a layer of silver halide crystals
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the lattice of silver halides that make up the emulsion is ____ % silver bromide and ____% silver iodide
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95% silver bromide
5% silver iodide |
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describe the process of formation of the latent image.
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xray deposits energy within the silver halide crystal
electrons are released and travel through crystal-- trapped in the sensitivity speck electrons drop out through the SSpeck migration of the electrons cause neutralization of the silver atoms--> Ag(s) |
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What is a long latitude film?
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low contrast --> many shades of gray
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What are the 3 causes of radiographic Fog?
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scatter radiation
safelight mismatching chemical fogging * the latter two occur during processing |
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What are 2 physical artifacts that can obscure the image of the radiograph?
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Pressure/bending--> before development causes focal exposure
Static electricity--> linear branching exposures (black streaks) |
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Subject contrast is based on variation in xray absorption due to 3 tissue characteristics. What are they?
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tissue thickness
subject density of the tissue anatomic number |
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List the5 tissue densities in decreasing radiopacity.
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mineral
bone soft tissue (water) fat air |
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What does attenuate mean in relation to radiography?
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the original beam is weakened
therefore more of the tissue is ABSORBING the xrays *thicker objects attenuate more of the xrays. |
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T/F: the latent image is visible to the eye
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False
*film processing converts the latent image of the exposed xray film to an image that is visible to the eye |
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What is the visible image of the xray film referred to as?
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Manifest image
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What are the 4 basic steps of film processing? briefly describe.
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developing--> converts exposed silver halide crystals into metallic silver (black)
fixing--> removes unexposed crystals Rinsing--> removes chemical residues that may cause yellowing/browning drying--> |
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What will the film look like if you "fix" a blank?
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Clear
*all the crystals are unexposed and so they are all removed |
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what step in radiograph processing is responsible for removing unexposed crystals from the emulsion and hardening it?
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fixing
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What will a film look like that has been inadequately rinsed?
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cloudy or sticky
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what controlled characteristic of the xray beam adjusts penetration?
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kVp
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what controlled characterisitc of the xray beam would you adjust if the film was overexposed?
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mAs
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in order for the shortest time of exposure to be achieved, the mAs should be set on the (highest/lowest) value allowed by the machine.
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highest
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How do you know if the mAs is properly set?
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the exposed portion of the radiograph should be BLACK.
if it is not then increase the mAs |
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What controllable xray characteristic should be adjusted if:
the periphery is dark Black, but the object is still white with high contrast. |
increase penetration by increasing kVp
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doubling mAs will double ____.
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film blackness
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increasing kVp _____% will double film blackness.
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10-15%
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10-15% icreasein kVp is equivalent to ____ x mAs
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2 (double)
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the human eye can only detect a 30% change in contrast from one film to the next. how much would you have to change the kVp in order to SEE a difference in the films?
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5%
*10-15% change DOUBLES the blackening(100-->200), so 15% splits into a third with 100(the doubled value) nicely with 5%= about 1/3, 33% change....... SO 5% would be about 33% change in blackening |
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T/F: mAs is directly related to exposure on a 1:1 basis.
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true
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which form of radiation has biological implications?
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ionizing
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What are types of NON ionizing radiation that we use in diagnostic imaging?
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ultrasound
magnetic resonance imaging |
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what are types of IONIZING radiation that we use in diagnostic imaging?
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radiography
computed tomography nuclear medicine |
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What makes up your total radiation exposure?
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environmental (internal, external)
medical (non-occupational) occupational |
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What are some environmental sources of radiation exposure?
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Cosmic radiation (protons)
earth elements (uranium, radon, thorium, gamma) human-made (tv, cell phones, tobacco, nuclear power plants) |
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radiation intensity varies with ___ due to earth's magnetic fields.
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Latitude
*greatest at north and south poles |
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Where does radon come from?
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radioactive noble gas formed from the decay of uranium
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T/F: lead shielding protects from primary and secondary beam exposure.
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false... only secondary--> scatter radiation
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lead sheilding can reduce scatter radiation by how much?
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1/20th
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What is the difference between the radiation absorbed dose and the effective dose
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radiation absorbed dose is only a MEASUREMENT
effective dose takes into account the type of radiation and the susceptibility of the tissue |
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What is the occupational exposure dose limit?
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whole body= 5 rem/yr
extremeties= 50rem/yr |
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what is the fetal dose limit?
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500mrem/ gestation
50mrem/mo |
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What is the LD50 for radiation exposure in humans?
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350 rem
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how many sieverts are in a rem?
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1 rem = 10 mSv
or 100mrem = 1mSv |
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What radiation particle has the highest weighting factor? which one is most hazardous?
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alpha particles
20 (vs 1 for xrays and gamma rays) |
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What tissues are the most sensitive to radiation exposure?
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ones that are highly proliferating... and undifferentiated.
gonads breast tissue GI bone marrow lung thyroid bone surface |
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What is the principle target for the biological effects of radiation?
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DNA
*irradiation leads to breaks in the helix that may or may not be repaired... manifestation of damage is based on the lack of repair or cell death |
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What is the difference between deterministic effects and stochastic effects?
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deterministic effects require a threshold dose
stochastic effects do not |
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At what stage in fetal development will fetal death occur due to radiation?
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0-2 weeks
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at what stage during fetal development is mental retardation most likely to occur due to radiation?
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8-15 weeks
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what does alara stand for?
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as low as reasonably achievable
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what is the inverse square law in reference to radiation?
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double your distance= reduce your radiation by a factor of 4---->
this works in reverse for TAKING radiographs... doubling tube film distance requires increasing radiation by a factor of 4 |
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what is the purpose of a collimator?
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decrease scatter radiation
improve image quality |
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what is the cheapest method of monitoring radiation absorbed dose?
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radiation sensitive film
*less precise, delay between exposure and access to info |
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What are the 3 components of the ALARA principle
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time
distance shielding |
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the vast majority of ionizing radiation energy is deposited as ___.
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heat
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____ discovered xrays in 1895
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wilhelm konrad roentgen
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the first death due to xrays occured in ___
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1904
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in ___, the british roentgen ray society adopted radiation protection recommendations
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1915
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cells can be damaged by radiation via direct injury or indirect injury. explain both.
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direct: ionization of DNA, RNA, or protein
indirect: production of free radicals that cause damage |
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what are the particulate types of radiation?
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alpha
proton electron positron neutron |
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what is a radiation dose equivalent?
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weighted dose based on type of radiation and its biological damage capability
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what is effective dose equivalent and what is it measured in?
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weighted dose equivalent for the WHOLE body
measured in rem |
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what category of radiation sources accounts for about 82% of the average persons radiation dose annually.
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background:
cosmic, thorium, uranium, radon, etc. |
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what determines the biological effects of radiation?
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rate of exposure
amount of body exposed tissue sensitivity |
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an ungloved hand in the primary beam: ___ mrem
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100 mrem
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scatter radiation to uncovered body parts: ____ mrem
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5 mrem
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how do u limit time of exposure?
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increase mAs, speed of film/screen, digital radiography, reduce repeats
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what type of radiation monitoring device can detect raidation down to 1.0mrem?
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optically stimulated luminescent dosimeter
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What level of radiation can a film badge detect?
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down to 20-30mrem... nothing below this.
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what is the goal of radiographic image geometry?
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reduce magnification, distortion, and unsharpness to improve image accuracy
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what are the 3 factors that influence magnification?
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tube film distance
subject film distance object size |
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so we want to maximize/minimize tube film distance and maximize/ minimize subject film distance.
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maximize tube film distance
minimize subject film distance |
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what are the two causes of distortion?
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unequal magnification
location in the beam |
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you can minimize distortion by adjusting
magnification position location views what do u do to each of these things? |
minimize magnification
position: keep objects parallel to film and perpendicular to the xray beam location: center the objects under the beam take 2 orthogonal views |
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edge gradient
rim of partial illumination partial shadow these are synonyms for ___. |
penumbra
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how does the focal spot cause penumbra?
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it has finite dimensions and acts as multiple point sources of xrays each generating a separate definition of the margin of an object
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penumbra can be minimized by decreasing ___ and ___.
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magnification
focal spot size |
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will a ball or a square have more absorption unsharpness?
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ball
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how do we reduce motion unsharpness?
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manual and chemical restraint
reduce exposure time |
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explain the heel effect?
|
the xray beam has greater intensity on the cathode side of the tube and less intensity on the anode side of the tube becauuuusee....
absorption of a portion of the xray bean occurs for those xrays produced deeper in the target because they have to traverse a greater distance to escape. |
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what factors influence the degree of the heel effect?
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angle of the target (steeper is more pronounced effect)
field size (larger fields/films are more noticeable) |
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how can you use the heel effect to your benefit?
|
arrange the patient so that the more intense xrays are aligned with the thicker portions of the animal (thorax)... and the less intense rays are penetrating the thinner portions of the animal(abdomen)
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what are the types of periosteal reactions?
|
solid smooth
lamellated spiculated amorphous *codman's triangle- may form at the edge of the lesion |
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Degenerative joint disease is usually secondary to ___ or ____.
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trauma
abnormal joint |
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_____ new bone occurs when osteophytes result from articular cartilage proliferation in the non-weight bearing areas of the joint in an attempt to stabilize the joint.
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periarticular
* excessive buildup of cartilage outfrows the ability of the synovial fluid to supply sufficient nutrients... cartilage dies... blood vessels invade he dead cartilage and replace it with bone. |
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____ new bone occurs when fibrocartilage elements form at the chodrosynovial junction to form a collar of new bone at the joint capsule attachment
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perichondral
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____ is an increased opacity of the subchondral bone. there is usually a loss of articular cartilage with direct bone on bone contact.
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subchondral osteosclerosis
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mineralization of the joint capsule and ligaments can be due to_____ secondary to chronic inflammation.
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dystrophic mineralization
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what are enthesophytes?
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new bone projections at the attachment of a ligament or joint capsule to bone-- bone spur
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____ is a decreased opacity in the subchondral bone. it can be cuase by necrosis of bone following loss of articular cartilage.
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subchondral osteolysis
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_____ is the proliferation of the synovium invading the subchondral bone. Most commony seen in the canine stifle.
|
subchondral bone cysts
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____ occur when the articular cartilage detaches resulting in free fragments in the articular space.
|
joint mice
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What are the types of bony lysis?
|
geographic lysis
moth eaten lysis permeative lysis |
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what is the difference between metastatic mineralization and dystrophic mineralization? and what is the third type of mineralizatoin?
|
metastatic is due to elevated serum calcium or phosphorus
dystrophic occurs in dead, devitalized or degenerative soft tissue Neoplastic mineralization |
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what are the tell tale signs of intracapsular swelling?
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cranial displacement of the infrapatellar fat pad
displacement of the fascial planes caudal to the stifle |
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what is the difference between endochondral ossification and intramembranous ossification?
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endochondral: mesenchymal cells differentiate into cartilage, takes place at physeal growth plates
intramembranous: mesenchymal cells differentiate into fibrous tissue, takes place on flat bones |
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Why would ultrasound be prefered?
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it has better soft tissue differentiation
it lacks ionizing radiation |
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What is the frequency of ultrasound?
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2-10 million hertz
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what produces the sound wave?
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piezoelectric crystal stimulated by voltages-- produces vibrations = sound wave
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what is the basis of sound wave reflection?
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tissue differences in acoustic impedence (the greater the difference in tissue density, the greater the amount of reflection)
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what would cause acoustic enhancement on U/s?
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soft tissue-fluid intreface
no attenuation of sound wave occurs through fluid. |
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what is M mode image display on U/s?
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one dimensional
displayed along a horizontal axis (time) the vertical axis (depth) *echocardiography |
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What mode of U/s show the pixelated image?
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Brightness (B) mode
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what kind of U/s transducer results in a pie shaped image?
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sector transducer
*good for small window spaces |
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what does anechoic mean?
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no internal echoes (black)
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what is the natural order of organ echogenicity?
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(Most)
renal sinus prostate spleen liver renal cortex renal medulla (least) |
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What are the advantages of using either high or low frequency u/s?
|
low = better penetration
high = better resolution *use the highest frequency that allows adequate penetration of the body part |
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T/F: ultrasound can be used to diagnose a detached retina.
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true
|
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What are some alternate imaging techniques?
|
digital radiography
computed tomography nuclear imaging fluoroscopy magnetic resonance imaging |
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What are the advantages of digital radiography?
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Ad:
no film no processing no storage space faster turnaround decreased need for retakes share images |
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what are the disadvantages of digital radiography?
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expensive purchase/ lease
DDR panels difficult to maneuver and easy to break lower spatial resolution |
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fluroscopy uses ____ and ___ to visualize moving internal structures
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xray energy
image intensifier |
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what alternative imaging technique positions the xray tube BENEATH the table and patient.
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fluoroscopy
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What is the difference between CT and MRI?
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CT uses xray energy
MRI uses magnetic field and pulses of radiofrequency energy |
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How does MRI work?
|
hydrogen atoms in the patient tissues align with the magnetic field
radiofrequency pulse knocks them out of alignment a weak energy signal (resonance) is released from the tissues as the hydrogen atoms realign with the magnetic field |
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what is more sensitive to brain lesions CT or MRI?
|
MRI
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___ is an imaging technique based on the selective accumulation of radioactive chemicals within tissues.
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nuclear imaging
|
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what is the most common radiopharmaceutical used in veterinary nuclear imaging? what is the half life of this product?
|
technetium 99
t1/2= ~6 hours |
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what type of radiation is utilized for nuclear imaging?
|
gamma
|
|
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T/F: a HOTSPOT is DARK on nuclear imaging.
|
true
|
|
|
T/F: a COLDSPOT is WHITE on nuclear imaging.
|
true
|
|
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What are the legal requirements of a radiographic label?
|
premanent
before development ownership of radiograph date patient identification |
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how does a photoprinter radiolabeling system work?
|
there is a blocker of the intensifying screen that protects a corner of the film during patient exposure... afterward the blocked portion is exposed separately to a light source through a card with the ID data (directly on the film)
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What are the disadvantages of leaded tape radiograph labeling?
|
difficult to read
often overexposed (because people don't use the filter backer). |
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What is the purpose of using contrast media?
|
create a differential density interface
enhance contrast |
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|
choice of CM is based on 2 things...
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organ to be studied
suspected abnormalities |
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Negative CM is usually air or CO2. What can this be used for?
|
pneumocystogram
pneumocolon pneumogastrography |
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Why is CO2 safer to use for negative CM studies?
|
more soluble
|
|
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What are the preferred uses of barium paste vs barium liquid?
|
paste -- esophageal
liquid--- GI |
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what are the factors that can cause the barium to drop out?
|
large particle size
blood/mucus/positive ions in lumen poor suspending agents |
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is barium toxic in high doses?
|
only if it leaves the lumen of the bowel.
*do not use if suspect gut perforation |
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what happens if barium gets into the pleural cavity? (reaction)
|
granulomatous inflammation
|
|
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how do you reduce the toxicity of iodinated CM?
|
add a less toxic (organic) molecule to the iodide
|
|
|
what is the chemistry of urographic organic iodinated CM?
|
water soluble
tri-iodinated benzoic acid derivativve |
|
|
what accounts for the physiologic and toxicologic effects of CM?
|
VERY hypertonic
|
|
|
T/F: CM has high protein binding.
|
false
*CM has very low protein binding. |
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|
How is urographic and angiographic CM cleared?
|
renal
|
|
|
What are some of the common side effects of systemic CM?
|
nausea
vomitting |
|
|
What are the advantages and disadvantages of iodinated CM in the GI tract?
|
ad: nontoxic if leaves gut (perforations)
dis: pulls fluid into bowel, accentuates dehydration, dilutes CM, irritates bowel, induces vomiting, rapid transit |
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|
what is acoustic impedence?
|
speed of sound in the tissue (constant) x density of the tissue
|
|
|
What are the new and improved iodinated CM?
|
nonionic
glucose derivatives *iohexol, iopamidol |
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|
Overexposure will " ____" subtle lesions
|
burn out
|
|
|
T/F: the more you can fit onto a single rad the better.
|
false.
*different areas need different positiong and exposure |
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|
What is a hot-light?
|
intense light source used to view overexposed areas on the film
|
|
|
What is the first thing that should be evaluated when you look at a film?
|
film quality... diagnostic or not.
|
|
|
T/F: some abnormalities are obvious but clinicall insignificant.
|
true
|
|
|
a ___ is a list of differential diagnoses that can account for or produce the radiographic findings observed.
|
gamut
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