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96 terms

PF Vet Tech Diagnostic Imaging

STUDY
PLAY
x-rays are a form of
electromagnetic imaging
radiograph
is the sheet of plastic and emulsion with an image on it
scatter radiation
radiation that changes direction when it hits the patient or table
collimator
is an apparatus that's located directly under the x-ray tube. it helps limit the size of the radiation beam coming out of the tube
if radiation damage showed up within the lifetime of the recipient, it would be called _____damage
somatic
what is a voltage compensator
a control used to manually adjust the transformer to compensate for inconsistent electrical output
the thickness requirement for radiographic protective apparel is _____lead equivalent
.5mm
what is the most common cause of x-ray tube failure
filament evaporation
the ____helps us to center the x-ray beam using light
collimator
what is the purpose of the aluminum filter, located between the x-ray tube and the collimator
eliminates the soft x-rays, which cause skin damage
the area hit by electrons after they pass across the x-ray tube is called the
target
due to the heel effect, the thickest part of an animal's abdomen should be placed
under the cathode side of the tube
to help dissipate heat, the x-ray tube contains
oil
changing the anode target angle from 20 degrees to 15 degrees will
increase the heel effect
a radiograph is an
image
what are radiation logs
radiation logs help track techniques used on repeat patients and radiation exposure of staff
what is the recommended way to check lead safety apparel
radiograph it at least annually
in the x-ray machine, the particles that are emitted by the heated filament are called
electrons
which of the following is a type of collimation device
diaphragm
mAs
milliamperage-seconds
kV
kilovoltage
when you take a radiograph does it make the items in the room radioactive
No radiation that comes from the xray tube loses its energy doesn't stay in the room to make objects radioactive
why is the xray tube enclosed in glass
the xray tube is enclosed in glass so a vacuum can be created
what is the purpose of a rotating anode
to dissipate heat more quickly and prevent damage to the anode
what determines the amount of absorption of the x-rays as they pass through an object
the atomic number of the material, the physical density of the object, andt he energy of the x-rays
the x-ray tube consists of a/an _____and a/an_____
anode;cathode
name 2 functions of the collimator seen on most stationary small animal machines
to limit the area covered by the primary beam, to prevent scatter radiation
what is a collimator made of
lead
what does a control panel do
the control panel allow the operator to control the x-ray machine and adjust the settings as needed
what is the minimal radiation exposure safety protection necessary when in the room during x-ray exposure
gowns and gloves of 0.5 mm lead equivalent are mandatory. It is recommended that eye and thyroid protection also be worn
what is a film badge and what is it used for
a film badge is a device worn at neck level outside the gown during radiation procedures to monitor how much radiation the worker is exposed to
What is the difference between primary and scatter radiation
primary radiation is radiation found in the x-ray beam leaving the machine. Scatter radiation is any radiation found outside the primary beam
why is it important in veterinary radiology to keep the mA setting as high as possible
when the mA is as high as possbile it means the time can be as low as possible. this is important due to animal movement. also shorter exposure times decreases radiation exposure to personnel
where is the grid located
the grid is located under the table and above the cassette holding tray.
List three functions of a cassette
A cassette is used to hold the intensifying screens, keep the film clean, and keep light away from the film
what is a latent image
The latent image is the image that's on a piece of film once the film is exposed to radiation; however, this image can't be seen because film development hasn't yet occurred
what is the difference between nonscreen film and regular film.
Screen film is placed in the cassette for use. Nonscreen film isn't placed in a cassette but is in its own lighttight paper envelope. Screen film is sensitive to light. Nonscreen film is sensitive to x-rays. Nonscreen film give a higher detail than screen film but also requires much more radiation to produce an image
when storing film, what three factors must be considered
The film storage must be lighttight, dry, and cool. It must also be free from radiation and must not have fumes from chemicals in sufficient amounts to be a detriment to the film
explain how a bone should be oriented to the casssette during a radiographic exposure. What happens if the orentation of this bone isn't as it should be
All bones should be parallel with the cassette and as close as possible to the cassette when the radiograph is taken. If one end of the bone is farther off the cassette than the other-or if t he entire bone isn't close to the cassette-then the end that's lifted will appear enlarged and less detailed
What stops scatter readiation from causing fog on the film
a grid
When the SID is changed, what happens to the image
its detail changes
When measuring an animal body part with a caliper to set the technique, the unit used is the
centimeter
You've just radiographed the leg of a dog and now need to radiograph the abdomen. For the film to be exposed correctly, the
kV setting needs to be increased
when developing, films should spend
twice as long in the fixer as in the developer
after placing the film into the tank for developing
gently shake the film to remove air bubbles
True of False. Fixing agents is part of the developing solution
False
Film thats used without intensifying screens takes more or less radiation for the exposure
more
the automatic processor takes less time to process film than hand developing because
it uses special chemicals and a higher developing temperature
when preparing the hand tanks for use, which of the following should you not do
add developer solution to the third tank
as a bone is pulled farther away from the film, what happens to the image
it gets larger on the resulting radiograph
which of these materials will allow the greatest amount of x-rays to be absorbed. Muscle, Air, Fat or Bone
Bone
According to the inverse square law, if you double the subject's distance from the x-ray tube, the x-ray exposure is
cut to one quarter
A special film must be used with an intensifying screen using rare-earth phosphors because
the crystals emit light in the green spectrum, which silver halide film won't absorb
to be sure a safelight stays safe, the light should be no closer than
four feet from the countertop
when radiographing a large dog using a grid, the radiograph comes out with poor density and white lines in some areas. you check you settings, and they're all correct. what could be the cause
the beam was misaligned with the grid's focus
a radiograph that was developed with exhausted developer solution would look too
light
what is the best way to remove hair and dust from an intensifying screen
dampen a gauze pad with cleaning solution and carefully wipe the surface
which type of film is made using larger crystals and requires less exposure by x-rays or fluorescent light from intensifying screens
Fast film
Name the five techinique charts that are normally kept for each x-ray machinge
Abdomen, thorax, extremities, pelvis/spine combo, avian/exotic
List 3 possible causes in the darkroom for a dark radiograph
Overdeveloped; fog due to improper lighting or light leak
List 3 possible causes in the radiology room for a light radiograph
not enough radiation; tube is too far away from the cassette; cassette was placed in the tray when it should have been placed on the tabletop
Which takes more radiation to make a good image, a cassette on the tabletop or a cassette placed in the holding tray
it takes more radiation to make an adequate film when the cassette is in the holding tray. More radiation is needed to penetrate the table and grid
What happens when the x-ray tube is moved closer to the table than the technique chart it is designed for
When the x-ray tube is moved closer to the film and the same amount of radiation is used, the film will come out too dark
When the film is placed in t he cassette but doesn't come into good contact with the intensifying screens, what happens to the image in that area
any area where the film doesn't come into good contact with the intensifying screens won't be as detailed as the rest of the film where good contact has been established
why is it necessary to check the collimator light against the x-ray beam
it is possible for the x-ray beam to be exposing an area different than what the light covers. this can be a great danger to the handler, who is relying on the beam being where the light indicates it will be
what causes the classic artifact that looks like a crescent moon
the crescent moon is a pressure mark made when a film is grasped between the thumb and forefinger. the film is bent at this point and a black artifact occurs.
You just took and processed a radiograph. It came out too dark. What could the problem be
overexposed or overdeveloped
A yellow radiograph could be caused by which of the following errors
residual fixer left on the film due to insufficient washing
The change in mAs that corresponds to a 15 percent change in kV is
50 percent
what should you consider when determining the technique for an animal body part
the thickness of the area and the part of the body
what is the correct way to view a lateral radiograph of a large dog
the head toward the left, the spine at the top
when formulating a technique chart, what is the effect of different intensifying screens
The mAs must be decreased for a fast screen
you were supposed to put the film in the tray but instead put it on top of the table. How will it look
Dark
The kV on a technique chart will change according to the
thickness of the animal part
Which grid-technique chart would require the least radiation for any given thickness?
Thorax
a black spot on a film could be caused by
static electricity
if a film is too light, what could be wrong
some part of the technique needs to be increased
for most veterinary clinic technique charts, exposure time usually need to be -------
doubled
the grid is used with all measurements on all technique charts for dogs and cats except for the
extremity/skull
define positioning
positioning is a description of how the animal is sitting and what body part, if any is stretched out or pulled on when the radiograph is taken.
define landmark
a landmark is something on the animal that can be palpated or seen that can help to tell us what to include in a radiograph, such a a bony protrusion, the end of a bone and so forth.
which skull view requires the x-ray tube to be tilted and why
an open-mouth nasal view or ventro-dorsal open mouth view. It is tilted to help prevent the mandible from superimposing over the nasal area.
name two ways the tympanic bullae can be evauated. give the positioning for each.
if both tympanic bullae need to be evaluated, two oblique lateral radiographs can be used. the animal is placed ina lateral position, and the head is rotated to the affected side. the open-mouthed typanic bullae view can also be used to evaluate the tympanic bullae. the animal is placed in dorsal recumbency, the nose is pointed toward the ceiling, the lower jaw is slightly opened and the beam is centered in the back of the mouth.
explain why most films are taken on expiration.
on expiration the exposure can be taken during a covenient little pause in respiration that the animal takes just after exhaling.
what films are not taken on expiration and why
in the case of the thorax we take the fim on full inspiration to see if its lungs are fully expanding
explain the bone rule
it states that when radiographing a bone, be sure to include the joint on each end of the bone to mae sure you've radiographed the full bone in between
explain the joint rule
when radiographing a joint, be sure to center directly over the joint and include only one to two inches of each of the bones that make up the joint
when radiographing the pelvis in a lateral position the legs should be
staggered for better viewing
to determine if a lateral skull view is truly lateral or not, the ______should be superimposed
top and bottom canine teeth
which of the following is a landmark for spinal radiographs
greater trochanter
when naming views, which of the following is correct
the first part of the word is where the beam enters the body
when does reticulation of the fil occur
reticulum occurs in the deveoping process when a film is moved from a chemical of one temperature to another chemical at a different temperature. the change in temperature causes reticulation
where in the darkroom is there most likely to be a light leak
around the door or seams in a suspended ceiling
what is meant by the wet side and the dry side of a darkroom
one area should house the wet materials like the hand-processing tanks and hangers. another should house materials that aren't supposed to get wet like cassettes and film.
why is it important ot keep the wet and the dry side of the darkroom separated
if film gets wet before it's ready to be placed in the developer solution it will be damaged. if intensifying screens are allowed to become wet of splashed with chemicals they could be ruined
what are the steps in the manual processing procedure
developer-wash-fixer-wash-dry