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86 Cards in this Set

  • Front
  • Back
Why is filtration material added to the fluoroscopy machine
to attenuate low energy X-rays.
What determines the effectiveness of a filter
the HVL (half value layer)
What is the HVL
attenuating material that reduces the beam inten-
sity by one-half at a specified kilovolt peak.
What is the HVL of a filter at 80 kVp
2.3 mm
What if the kVp is greater than 80 kVp
it should be increased
What is the most common filtration material
aluminum
Besides what other fitration is used for x-ray filtering
copper
What are 2 factors that must be considered when designing a table for a flouroscopy machine
patient suppurt
not decreasing the attenuation of the x-rays
Why is it particularly important not to have much attenuation caused by the table in over table xray tube configurations
low attenuation tables decrease radiation dosage
What is a table usually made out of
carbon fiber
Why are grids used in flouroscopy
Anti-scatter grids are used to improve image con-
trast by reducing the scattered x rays that reach
the image receptor.
What is the typical grid ratio for a fluoroscopy table
The grid
ratios for fluoroscopy range from 6:1 to 10:1,
which is generally lower than common radio-
graphic grid ratios (8:1 to 16:1)
What has a higer grid ratio...fluoro or plain film
plain film
Do grids increase the patients exposure to X-ray scatter
yes
What is the benefit of an X-ray grid
better contrast
Is an X-ray grid always required
no
When should the grid be removed
if there is not going to be alot of scatter
When is a grid not needed
a
grid is not needed if a large air gap between the
patient and the image intensifier is required for
geometric magnification, access to the patient, or
access to interventional devices
How much can patient exposture be reduced if the grid is removed
up to 50%
Is removing the grid always feasible
depends on the machine. Sometimes it is easy and sometimes not.
Where is an X-ray grid located
just below the image intensifier
If the patients body part is small or if there is a small field of view what happens to the contrast
it is improved. (might consider no grid)
If the image intensifier is widely seperated from the patient is there need for a grid
no
What does an image intensifier do
The image intensifier converts incident x rays
into a minified visible light image and, in the pro-
cess, amplifies the image brightness by about
10,000 times for better visibility to the viewer.
What are the major components of the image intensifier
input layer
anode
output layer
What is the input layer
converts X-rays to electrons
What is the input layer made of
The input layer is made up of four different
components: the input window, substrate, input
phosphor, and photocathode.
What does the input layer look like
What is the purpose of the electron lense
(this is a main part and was left out of the previous card)
electron lenses to focus the electrons
What does the anode do
accelerates the electrons
What do the electron lense and anode look like
What is the function of the output layer
them, and an output layer to
convert them into a visible image
Are all the components of the image intensifier in an evacuated bottle
yes
What is the path of the x-ray as it moves through the input layer
irst, x rays strike
the input window, which is made of a curved,
thin layer of metal or glass. Next, they pass
through the 0.5-mm-thick aluminum substrate
layer and input phosphor layer, where they are
converted into light photons.
What happens to the light photons as they travel to the photocathode
The light pho-
tons emitted from the input phosphor are then
absorbed in the photocathode and converted into
electrons.
What is the input phosphorus made of
cesium iodide
What happens to the electrons after they emerge from the photocathode
they are accelerated through a vacuum to the output layer by the electon optic system
What does the electrons optic system do
it accelerates the electrons to the output layer
What makes up the electron optics system
three charged electrodes and an anode plate at the output layer
How does the electron optic system do
hese components create an electric potential,
which intensifies and demagnifies the electron
beam to the size of the small output layer
What happens to the electrons at the output phosphorus
At the output phosphor, the electrons are converted into
visible light photons.
What happens to the light photons after the output phosphorus
These photons are then
transmitted out of the image intensifier through a
glass output window.
What happens as a result of the acceleration of the electrons and minification of the image
the illumniation level of the output image compared to the input is greatly increased
What is the illumination level known as
brightness gain and ranges from 5k to 20k
What are the typical input window size for image intensifiers
Image intensifiers are available with different
diameter input windows of 10-40cm
What determines the size of the input windo
The selec-
tion of the diameter depends on the maximum
FOV requirements of the clinical application.
What does size of the image output window do
adjust to field of view
What occurs in the magnificaiton mode
In magnifica-
tion mode, the central circular area of the input
layer is focused onto the full output layer by ad-
justing the voltage of the electron optics electrodes.
What is the function of the optical coupling system
The optical coupling system distributes light
from the image intensifier output window to a video camera and other image recording devices
Where is the optic coupling system located
What does the optic coupling system look like
What is the reason for a partially silverd mirror
to spit the light beam and directs a portion of the light from the image intensifier output window to an accessory device
for image recording and passes the remainder to
the video camera.
What does the beam splitting mirror look like
note some of the light going to the accessory port and some to the video camera
Where is the optical coupling system aperture located
What is the reason for the circular aperture
A circular aperture is also in-
cluded to set the proper light level required by
the video camera. The aperture setting affects the appearance of noise in the fluoroscopic image.
How do the circular aperture and the ABC system work together
When the aperture is set to a small size, much of
the light from the output window is blocked from
reaching the video camera. As a result, the ABC
system increases the radiation exposure to main-
tain the light level at the camera, producing a
fluoroscopic image with low noise.
What happens when the aperture is wide open
the radiation exposure is low and there is more image noise
What happens when the aperature is small
there is more radiation and less noise
What is the advantage of having an analog to digital coverter
digital information can ct processed
What part of the video camera recieves the signal from the optic coupling lens
a 2.5 cm photoconductive target
What is contained in the vacuum tube cylinder
a photoconductive target and a scanning beam
What part of the video camera recieves the signal from the optic coupling lens
a 2.5 cm photoconductive target
What is contained in the vacuum tube cylinder
a photoconductive target and a scanning beam
What does the vacuum tube of the video camera look like
What signal is hitting the photoconductive surface of the video camera
light
What happens to light as it focuses on the photoconductive layer of the video camera
he optical coupling lens focuses
the image intensifier output image onto the tar-
get, forming a latent charge image from the
charge carriers within the photoconductive layer.
Where is the electron beam in the vacuum tube of the video camera
How does the electron beam work
This latent image is read out by the electron
beam, which scans across the target in a series of
horizontal raster lines
What is the horizontal raster scanning pattern
bottom left
What is raster scanning
raster scanning, is the rectangular pattern of image capture and reconstruction in television
What happens as the scanning electron beam moves across the target
As the scanning electron
beam moves across the target, a current signal is
produced that represents the two-dimensional image as a continuous series of raster lines with
varying voltage levels
What is a charge coupled device camera
Charge coupled de-
vice (CCD) cameras consist of a solid-state array
of light sensors, which store the image as pixels
until they are read out as voltage pulses repre-
senting the two-dimensional image
What are the advantages of CCDs
Compared
with traditional video cameras, CCD cameras are
smaller, are more rugged, require less power, and
have a longer lifetime.
What are some additonal devices that a flouroscopy machine may have to record images
5
spot film de-
vices, film changers, photospot cameras, cine
cameras, and digital photospots
What are spot film devices
Spot film devices are used to acquire a radio-
graphic image with a screen-film cassette that is moved into position in front of the image intensi fier
What does an under the table Xray tube RF system look like
What is a film changer
these acquire radiographic film either in front of the image intensifier or with it move out of position
What are some alternative names of a film changer
rapid film changer, se-
rial film changer, cut-film changer, Puck
How does a film changer work
Films are moved rapidly
into position from a supply magazine at a select-
able rate up to four films per second and then
transferred to a take-up magazine for manual
transport to a film processor.
How fast can a film changer wokr
4 films a second
What does the photospot camera do
Photospot cameras record the image intensi-
fier output on rolled or cut film to produce im-
ages about 10 cm in diameter.
Where is the photospot camera mounted
on the optical distributor ac-
cessory device port to record images rapidly dur ing the fluoroscopic examination.
What is a photospot film used for
Photofluorog-
raphy is generally used for the same clinical ex-
aminations as spot film devices
A cine camera
may also be mounted as an accessory image re-
cording device to acquire images on 35-mm film.
Cinefluorography is typically used for cardiac
catheterization procedures to record rapid rate
images of the beating heart
yes
What have all of the imaging methods i just wasted my time making cards for been replaced by
Digital photospots are acquired by re-
cording a digitized video signal and storing it in
computer memory. The operation is fast and
convenient, plus image quality can be enhanced
by the application of various image processing
techniques, including window-level, frame aver-
aging, and edge enhancement. However, the spa-
tial resolution of digital photospots is less than
that of film images
What is a RF table
radiography/flouroscopy table