final Flashcards
When measuring a body part of varying thickness the caliper should be placed
along the path of the central ray.
The electrical component that temporarily stores a charge is known as
a capacitor.
The maximum exposure that a back-up timer may legally deliver is
600 MAS.
An ionization chamber consists of
two sheets of metal between which is found air.
When using AEC the technologist surrenders control of
S (time)
In using ionizing chamber AEC devices electrons are sent to a
capacitor.
Selecting the wronged bucky when using AEC will result in
a long exposure time, the need to repeat the image, unnecessary exposure to the patient.
The recommended back- up timer for an exposure expected to be 50 MAS should be
75 MAS (150%)
With a fixed KVP technique chart variation for a patient size is
based upon +/- 20% MAS per cm.
When using AEC, collimating the selected ion chamber out of the exposure field will result in
overexposure of the image.
An increase in film screen speed when using AEC will result in
increase in image density.
When using AEC having a low mA setting will result in
a longer exposure time.
With a variable KVP technique chart variation for patient size is based upon
+/- 2 KV per cm.
It is recommended that the AEC back-up timer be set at
150% the expected MAS.
The cells of an ionization chamber AEC device are found between
patient and image receptor.
When using AEC, decreasing collimation (larger field size) will result in
underexposure of the image.
The technologist
does not need to adjust the AEC density control settings for all patients.
AEC is designed to
compensate for variations of patient thickness and pathology.
A tech can select
multiple photochambers per x-ray exposure.
The technologist has to be extra careful
with positioning when using AEC.
Ionization chamber type AEC devices
are the most common type seen today.
when using the small cassette the technologist should
select only the center chamber.
Changes in KVP result in
changes in image contrast.
Refining a technique chart is a
a never-ending task.
Goal of AEC-
to obtain the same density and quality image with every exposure regardless of patient size and pathology.
Undercutting when using AEC- means
collimating too much therefore not having full selected AEC cell in collimation field.
Anatomically programmed radiography-
radiography where the control console allows you to select for your patients build (sthenic, hypersthenic, asthenic, etc.) and it makes the appropriate technique adjustments for you.
Anthropomorphic phantom-
phantom meant to mimic a human body so that you can get a technique chart started without having to expose humans.
The function of the reducing agents in developer solution is
to change silver ions into black metallic silver.
The device that measures film density is known as
the densitometer.
The sequence of order through an automatic processor is
developer, fixer, washer, dryer.
The addition of an electron to a positively charged silver ion results in
black metallic silver.
Removal of unreduced silver halide crystals happens in the
fixer.
As radiographic film speed decreases film detail
increases.
As radiographic film detail increases film contrast
is not affected.
Developer solution giving up electrons results in
its oxidation.
The addition of an electron to a positively charged silver ion results in
its reduction.
The minimum change in density for the human eye to see is
30%.
The margin for technique error is known as
latitude.
The portion of the sensitometric curve representing minimum optical density is known as
base +fog.
A sensitometric curve will tell you all of the properties of the film in question
except spectral sensitivity
The device that delivers a precise exposure to the film for sensitometry is known as
the sensitometer.
The portion of the sensitometric curve representing maximum optical density is known as
D-max.
The range of grays that a film is capable of recording is
demonstrated by the straight line portion.
As the amount of reduction in a film’s emulsion increases the effect on the film is
increased density.
The latent image is made manifest in
the developer.
The image held in the chemical code within a film’s emulsion is known as
the latent image.
The rate at which sensitometry must be performed is
daily.
As radiographic film contrast increases film latitude
decreases.
The number of density steps in a sensitometric scale is
21.
The acceptable range of variation in sensitometric speed and contrast measurements is
+/- .15 OD
Developer solution is sensitive to
everything.
As radiographic film speed increases film latitude
does nothing because speed and latitude are not related.
An aluminum step wedge used for sensitometric testing is known as
a penetrometer.
Speed and detail are related.
Speed and detail are related.
Latitude and contrast are related.
Latitude and contrast are related
Sensitometry- the amount of light absorbed by a film.
the amount of light absorbed by a film.
Base + Fog-
the whitest a film can get. It is the dyed base plus any environmental energy the film has received.
Film latitude-
the margin for technique error for a given film.
Film speed-
how fast a film can develop an image based on size of crystals.
Larger silver halide crystals make for a faster film speed whereas smaller crystals make for slower film speed.
Larger silver halide crystals make for a faster film speed whereas smaller crystals make for slower film speed.
The smallest component of a radiographic digital image is known as a pixel.
a pixel.
Measuring the distance from the center of a pixel to the center of an adjacent pixel is known as pixel pitch.
pixel pitch.
The laser found in CR imaging processor is helium-neon.
helium-neon.
The exposure indicator for Agfa brand CR imaging products is LGM
LGM
The wavelength of the red laser light used in a CR processor is approximately 600 nm.
approximately 600 nm.
The weakening of a stored latent image within a CR imaging plate is known as
fading
In a CR system, stored electron energy is trapped in the
F centers.
The color of visible light emitted by photostimulated luminescence in a CR system is
purple-blue.
The number of grays that an individual pixel is capable of demonstrating is known as
bit depth.
In a CR system, visible light emitted by the imaging plate is collected and channeled by the
light gate/fiber optics.
The mathematical formula used to process the digital image is known as
algorithm.
With CR digital imaging a “perfect” exposure indicator measures radiation to the IP at a dose of
1 mR.
Measuring the distance from one side of a pixel to the other side is known as
pixel size.
Within a radiographic CR cassette is found an
imaging plate.
The phosphor material found within a CR imaging plate is
europium barium fluorohalide.
The capture element of CR digital imaging is
europium barium fluorohalide.
The process of translating an analog image to a binary code is known as
digitizing.
The coupling element of CR digital imaging is the
light gate/ fiber optics.
The crossed rows and columns that form the framework of a digital image are known as
matrix.
The amount of radiation received by the CR imaging plate is measured and expressed as
exposure indicator.
CR plates are erased and made ready for re-use by
exposure to high intensity visible light.
All of the following terms are synonymous with digital image contrast ability
pixel depth, dynamic range and bit range.
The exposure indicator for Fuji brand CR imaging products is
s number.
Information expressed in variable physical quantities is known as
analog.
In a CR system, the latent image is held within the
photostimulable phosphor.
The 3-D pieces of digital information obtained by CT scan are known as
voxels.
Computers see, store, and transfer information in a language that is known as
binary code.
Information expressed in variable numeric quantities is known as
digital.
The number of pixels per given area is known as
pixel density.
The component in a CR system that converts visible light energy into electrical energy is the
photomultiplier tube.
The input phosphor of an image intensifier is composed of
cesium iodide.
The minimum source to skin distance for a mobile fluoroscopy machine is
12 inches.
KVPxMAxTimexRectification Factor is the
formula for calculating heat units.
The anode of an image intensifier is shaped like a
donut.
The voltage that accelerates electrons from cathode to anode in an image intensifier is
approximately 25-30 KV
The exposure timer used in fluoroscopy must alarm at time increments of
every 5 mins.
The area where electrons impact the anode is known as
the true focal spot.
The component of an image intensifier that converts electron energy into visible light energy is the
output phosphor.
As focal spot size increases
image quality decreases.
Tools that can be used to measure focal spot size include
line pair tool, star pattern tool, and pinhole camera.
The minimum source to skin distance for a fixed fluoroscopy machine is
15 inches.
The component of an image intensifier that converts visible light energy into electron energy is the
photocathode.
The technical factors used in a fluoroscopy machine are
high KVP and low MA.
Lead aprons worn by a technologist in fluoroscopy must have a minimum lead equivalency of at least
.5 Pb/Eq
The photocathode of an image intensifier is composed of
antimony.
The bucky slot cover used in fluoroscopy must have a minimum lead equivalency of at least
.25mm Pb/Eq.
The component of an image intensifier that converts x-ray energy into visible light energy is
the input phosphor.
The rectification factor of a single-phase x-ray generator is
1.0.
The output phosphor of an image intensifier is composed of
zinc cadmium sulfide.
The phosphor material used in medical imaging specifically for its needle like crystals is
cesium iodide.
The lead drapes used in fluoroscopy must have a minimum lead equivalency of
at least .25mm Pb/Eq.
As MAS increases blooming of the focal spot
increases.
The rectification factor of a high frequency x-ray generator is
1.4.
The true focal spot projected towards the patient is known as
the effective focal spot.
the factor which has primary control of image density is
MAS
The addition of a grid will result in
increases contrast
grids should be used with body parts measuring
10cm or more
the factor which has primary control of radiographic contrast is
KVP
The accidental superimposition of 2 grids will result in
moire effect
an increase in KVP will result in
decreased image contrast
grid frequency refers to
the number of lead strips per cm/inch
an increase of OID will result in an increase in
image contrast
the invention of the grid is credited to
Bucky
grid frequency is also known as
strip density
an image that is mainly black and white and possesses few grays exhibits
high contrast
a grid should be labeled with the exception of the
expiration date
the addition of a grid will result in
a decrease in image density
increasing grid ratio will result in
decrease in image density
increasing grid ratio will result in
shorter scale contrast
the interaction most responsible for the production of scatter is
Compton
switching from a low to high ratio grid will result in
higher contrast, and more MAS required
switching from a high to a low ratio grid will result in
lower contrast and less scatter reaching film
as KVP increases, patient bored dose
decreases
an increase in KVP will result in
increase in image density
scatter production varies by
amount of tissue irradiated, kilovoltage, composition of tissue irradiated
the grid error that occurs with CR digital imaging is known as
aliasing
the gird error that occurs when more than one grid is in the path of the primary beam is known as
moire effect
the grid error that occurs when exposure time is too short is known as
stroboscopic effect
the techs best tool for minimizing the production of scatter radiation is
collimator
the techs best tool for minimizing the impact of scatter radiate on the image is
grid
grids used with CR digital imaging systems must have at least
178 lpi
the standard formula for calculating an air gap technique in place of a grid is
10% of the SID
All of the following should be labeled on the grid
grid ratio, direction of grid lines, and strip density
the term grid clean up refers to
the grids efficiency in absorbing scatter
an image that is composed of many shades of try exhibits
low contrast
grid ratio is determined by
the relationship of the height of the lead strips to the distance between the lead strips
Scatter contributes the following to the finished image
grayness or blur can add density, definition of an image
primary benefit of a moving grid over a stationary grid
blur out the lines of the grid
2 materials that might be used as grid interspace material
plastic and aluminum
3 things that can happen to an xray
passes through - good
absorbed - good
scatter - bad
the factor which has primary control of image density is
MAS
Decreasing collimation (larger field size) will result in
longer scale contrast
increasing filtration of the X-ray beam will result in decreasing in
image density
the factor which has primary control of contrast is
MAS
the test performed to evaluate film/screen contacts known as
the wire mesh test
an increase in KVP will result in
increased image contrast
overall image blackness is known as
density
an increase in OID will result in decrease in
image density
increasing collimation (smaller field size) will result in
decrease in image density
to maintain image density when increasing KVP by 15%
the MAS must be decreased by 50%
an image that is mainly black and white and possesses few grays exhibits
high contrast
an increase in film/screen speed will result in
increase in image density
the addition of a grid will result in
decrease in image quality
when chugging rom RS800 to RS100, the size of dots will
decrease
the average photon strength in the polyenergetic primary beams expressed as
KVP
The geometric factors include
detail and distortion
an increase in SID will result in decrease in
image density
as KVP increases patient absorbed dose
decreases
an increase in KVP will result in
increase in image density
increasing collimation (smaller field size) will result in
higher contrast
the primary function of contrast is to make
recorded detail visible
a decrease in OID will result in
decrease in image contrast
the addition of a grid will result in
increased contrast
to maintain image density when decreasing KVP by 15%
the MAS must be doubled
the photographic factors include
density and contrast
when changing from RS200 to RS400 image quality
will not occur
the number of X-rays in the geometric primary beam is expressed as
MAS
all of the following are examples of positive contrast agents except
carbon dioxide
all of the following are examples of positive contrast agents except
KVP
increasing OID will not result in
in decreased penumbra
increasing SID will not result in
in increased penumbra
the area where electrons impact the anode is known as the
focal spot
recorded detail can be improved by
increasing SID
the amount of penumbra seen on a radiographic image is decreased by
a decrease in OID
the combination that will produce the greatest image detail is
long SID, short OID
contrast is not synonymous with detail
correct
the total number of electrons traveling from cathode to anode is measured in
MA
the approximate range of effective focal spot sizes is
.5-2.0mm
the number of electrons thermonically emitted from the filament per second is known as
MA
the true focal spot projected towards the patient is known as
the effective focal spot
the latent image is made manifest in this section of the automatic processor
developer
the modern X-ray imaging with film, the amount of tim exposure due to visible light is
approximately 90-99%
a blue dye is added to a radiographic films base layer to reduce both
glare and crosswalk
the phenomenon of visible light emitted from a phosphor crystal stimulated by X-ray is known as
luminescence
orthochromatic film is sensitive to all colors of visible light except
red
modern intensifying screens have phosphor crystals composed of all the following except
calcium tungstate
the color of visible light emitted by a phosphor crystal is known as its
spectral emission
the speed of a phosphor crystal is also known as its
sensitivity
cellulose nitrate cannot be found in the
films emulsion layer
the efficiency of an intensifying screen in converting X-ray energy to visible light energy is its
conversion efficiency
the invisible image held in chemical code within the films emulsion is known as the
latent image
as the size of a films silver halide crystals increases the films speed
increases
the addition of an electron to positively charged silver ion results in
black metallic silver
the conversion of efficiency of a rare earth phosphor intensifying screen is approximately
15-20%
the temperature of developer solution in an automatic processor should be
approximately 95 degrees F
panchromatic film is sensitive to all colors of visible light except
ALL light
the base modern radiographic film is composed of
polyester
structure mottle in screens or film results from
uneven distribution of crystals
the most commonly foun crystal in radiographic film is
silver bromide
the layer of radiographic film that holds the anatomical image is the
emulsion
in an automatic processor the emulsion is shrunk and the film is sealed in the dryer section by
hot air
the protective layer does not include
gelatin
the color of visible light emitted by a phosphor crystal is known as it
spectral emission
the reflective layer of an intensifying screen is most commonly composed of
titanium dioxide
as radiographic speed increases, film detail and image quality
decreases
the size and distribution of silver halide crystals control all of the film characteristics except
spectral emission
developer solution is sensitive to
changes in contamination, concentration, and temperature
as the size of liver hide crystals increases the films ability to visualize fine atomically structures
decreases
visible light emitted from a phosphor crystal stimulated by X-ray proceeds
in all direction
characteristics of fast intensifying screen include
high speed and thick phosphor layer
the need for chemical replenishment in the automatic processor is due to the effects of
processing films, oxidation of chemicals, and evaporation of chemicals
the area of a silver halide crystals that “captures” liberated electrons and other debris is the
sensitivity speck
the function of reducing agents (electron soup) in developer solution is to
change silver ions into black metallic silver
removal of unreduced silver halide crystals happens in
the fixer
silver halide crystals within the films emulsion are held together
by ionic bonds
the temperature of the dryer section should be approximately
130-135 degrees
as the age of an intensifying screen increases the speed of screen
decreases
the addition of an electron to a positively charged silver ion results in its
reduction
the color of visible light that a radiographic film is most sensitive to is known as its
spectral sensitivity
as the amount of reduction in a films emulsion increases the effect on the film is
increased density
a brown tint that develops in a stored X-ray film is likely due to
hyporetension
stored radiographic film is sensitive to
visible light, high temperatures, and chemical vapors
the wash section of an automatic processor is filled with
filtered water
the function of the wash section of the processor is to
remove fixer from the emulsion
characteristics of high speed radiographic film include
large silver halide crystals
the standard processing time for modern automatic processors is
90 second
developer solution electrons results in its
oxidation
the sequence of order through an automatic processor is
developer fixer, wash, dry
latent image formation occurs in radiographic film due to the
gurney-mott theory
characteristics of high detail radiographic film include
small silver halide crystals and single emulsion
characteristics of detail intensifying screen include
small phosphor crystals, slow speed, and a thin phosphor layer
intrinsic factors of an intensifying screen include
phosphor crystal material, phosphor crystal size and phosphor layer thickness
