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Bushong CH 12

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an easily observable difference between x-ray film and photographic film
the thickness & rigidy of the base
the principal characteristic of emulsion that make it particularly x-ray sensitive is its
sensitivity center
average silver halide crystal surface size in radiographic film if oproximately
1.0 um
the radiographic film base appears blue
so that image viewing is more confortable
radiographic film base of 1914-1920
cellulose nitrate
radiograpghic film base of 1920-1960
cellulose triacetate
the emulsion that is commonly used in x-ray film consist of
silver halide & gelatin
a common base for contemporary x-ray film is
polyester
in the manufacture of radiographic film
direct exposure film contains a thicker emulsion layer with a greater number of silver halide crystals
the adhesive layer of radiographic film
ensures uniform adhesion of the emulsion to the base
the 2 basic parts of parts of radiographic film
base & emulsion
the overcoat usually consists of
gelatin
dimensional stability is the property of maintaining the size and shape of what?
Base
When polyester is compared with cellulose triacetate as a base, what does not apply to polyester?
Thicker
The principal purpose of gelatin in the emulsion is to
support the silver halide crystals uniformly
What property of silver halide is most important in the production of a latent image?
Atomic number
X-ray film is sensitive to what?
Only x-rays, gamma rays and visible light
X-ray film used with radiographic intensifying screens usually has what?
An emulsion coat on both sides of the base
What is usually thinner than 5 um?
Emulsion
What is a principal component o fthe emulsion?
Silver bromide
The latent image actually is formed in the
silver halide crystal
During the photographic process, metallic silver accumulates at the
sensitivity center
The latent image at the crystal level
is a collection of silver atoms
The term latent image actually refers to what?
an unprocessed image
The sensitivity center is usually silver
sulfide
In the manufacture of the emulsion, what molecule is particularly sensitive to visible light?
AgBr
When the latent image is processed, what type of image does it become?
Manifest
What do we call the radiation exiting the patient that is responsible for latent image formation?
Image-forming
What do we call the radiation exiting the patient that is responsible for latent image formation?
Remnant
When x-rays interact directly with film what is most likely involved?
Silver
An ion is an atom
that has electric charge
The interstitial atoms in a crystal of silver halide include what?
Silver, bromine and iodine
X-ray interaction with silver halide can result in formation of all except what?
a radioactive atom
After irradiation, a secondary electron most likely will interact with a silver ion to form
a silver atom
In a silver halide crystal, what is missing an electron?
silver
What statement about processing is true?
It is required for manifest-image formation.
The latent-image center
forms at the sensitivity center
The formation of a latent image follows which interaction with the emulsion?
Photoelectric effect
If one observes a film immediately after exposure, what is seen?
Nothing
What theory best explains the photographic effect?
Gurney-Mott
The most commonly used radiographic image receptor is what?
Screen film
What is not a characteristic the radiographer should consider when selecting film?
Light emission
The contrast of aradiographic film is
inversely proportional to its latitude
High-contrast film has what?
uniform grain size
The difference between fast film and slow film is silver halide crystal
concentration
The spectral response of an emulsion refers to
its absorption of visible light
Calcium tungstate screens emit what?
Blue light
What will not fog film?
Fringe magnetic fields from an MRI
Orthochromatic film is sensitive to what?
Green light
What is the principal result of using rare earth screens with green-sensitive film?
Reduced patient dose
When rare earth screens are in use, what type of safelights are required?
Red
Mammography film
is used with a screen
When comparing 35-mm cine film with 16-mm film, the 35-mm film can be seen to have
Four times the area
Most rare earth screens emit what?
green light
If film is stored near steam pipes, the most likely result will be what?
lost of contrast
What is most likely to fog film?
An improper safelight filter
What are acceptable storage conditions for film?
16 degrees C and 10% humidity
What darkroom condition is not acceptable?
Green-sensitive film, amber safelight
What is the least important characteristic of screen film?
Light emission
What would be considered an image artifact?
A pressure mark
If other factors are equal, what emulsion is fastest?
Large grain
Radiographic intensifying screen speed increases with increasing
Phosphor thickness
Direct-exposure, nonscreen technique
results in better spatial resolution
Afterglow is a property of intensifying screens that
results in image blur
The resolution achievable with radiographic intensifying screens is approximately
5 lp/mm
What factor controlled by the radiologic technologist affects radiographic screen speed the most?
kVp
When screen film is the image receptor, image quality is a trade-off among speed, spatial resolution, and noise. In general...
... as speed increases, so does noise.
At x-ray energies below the K-shell electron binding energy...
...the incident photon does not have sufficient energy to ionize K-shell electrons.
The intensification factor...
is greater for rare earth screens than for calcium tungstate screens.
A phosphor currently used in radiographic intensifying screens is
barium fluorochloride
Screen blur..
is the loss of sharpness of an image when screens are used
With regard to luminescence, what is true?
There are 2 types: flurorescenece and phosphorescenece.
Radiographic intensifying screens are used with radiographic film principally to
reduce patient radiation exposure
Radiographic intensifying screens are used with radiographic film
reduce motion blur
What following property principally determines screen blur?
Phosphor cystal size
Luminescence is a process that
involves outer-shell electrons
Because x-ray interaction with a phosphor produces light isotropically...
the light spreads out.
Mammography conducted with detail screens results in entrance skin exposures (ESE) as low as 300 mR (3 mGya). The intensification factor for these screens is about 30. If such an examination were conducted as a nonscreen procedure, what would be the ESE?
9000 mR
What is a rare earth element?
Gadolinium
In the formula La202S:Tb, the Tb...
improves luminescence
The principal advantage of rare earth screens over calcium tungstate screens is
faster speed
Rare earth screens exhibit higher x-ray absorption than calcium tungstate screens
only a high x-ray screens
What element has the highest atomic number -- Gadolinium, Lanthanum, Molybdenum, Tungsten, Yttrium
Tungsten
What principally contributes to the increased speed of rare earth screens?
conversion efficiency
What following spectra is discrete?
Rare earth emission
Compared with calcium tungstate, rare earth screens...
have higher rates of x-ray absorption in the diagnostic range
When diagnostic x-rays interact with rare earth phosphors...
the lower the x-ray energy, the more probable is photoelectric absorption
When rare earth intensifying screens are used...
... there is an abrupt increase in absorption at an energy equal to the K-shell binding energy.
Compared with calcium tungstate, rare earth screens...
absorb three to five times as many x-rays
Compared with calcium tungstate screens, rare earth screens..
emit more intense light per x-ray interaction
Compared wtih calcium tungstate screens, rare earth radiographic intensifying screens...
result in lower patient dose
What statement is true about radiographic intensifying screens?
All screens have conversion efficiencies greater than one.
What statement is true about radiographic intensifying screens?
Rare earth screens must be used in carbon fiber cassettes
What statement is true about radiographic intensifying screens?
They are used to reduce patient dose.
What is the principal limitation of the rare earth radiographic intensifying screen?
Increased quantum mottle
In the proper design and use of a radiographic cassette...
Scratches on the front cover indicate that replacement is necessary.
In the proper design and use of a radiographic cassette...
The back cover should be made of high Z material to reduce scatter radiation.
In the proper design and use of a radiographic cassette...
The front cover should be made of low Z material to minimize x-ray attenuation.
At what stage in automatic processing is the latent image made visible?
Developing
What is the component of the developer that helps to keep unexposed crystals from the developing agent?
Potassium bromide (restrainer)
What stage of processing involves a synergistic reaction?
Development
Aerial oxidation is controlled by what?
The preservative
The hardeners in a fixer ...
ensure archival quality
What is the most common result of inadequate washing?
Excess hypo retention
Covnersion of the latent image to a visible image occurs...
in the developer
What ingredient of the developer is responsible for producing the blackest parts of a radiograph?
Hydroquinone
During development, silver...
ions are changed to atoms
The archival quality of a radiograph is principally...
established during fixing.
What term does not belong? Clearing agent, fixer, hypo, stop bath, thiosulfate
stop bath
What is not a separate stage in automatic processing?
Wetting
What is the preservative normally used in both the developer and the fixer?
Sodium sulfite
what is a reducing agent?
Hydroquinone
What ingredient in the fixer functions as a stop bath?
The activator
Hypo retention refers to what?
Thiosulfate left in the emulsion
Development fog will increase when what is abnormally low in the developer?
Potassium bromide
What is the component of the developer that is most responsible for archival quality?
Hydroquinone
The wetting agent used in automatic processors is usally what?
Water
The temperature of the washe water should be approximately...
5 degrees F (3 degrees C) below the developer
What is sometimes used as a developing agent?
Phenidone
What is an assembly that consists of one master roller, several planetary rollers and two guide shoes?
A turnaround assembly
Replenishment of what tank in the processing system is most important?
Developer
When a film is inserted into an automatic processor...
the short dimension should be against the rail.
Adequate drying is necessary to...
reduce artifacts
The fastest automatic processors can process a film in...
90 seconds
Between the fixing tank and the wash tank, the film passes through a...
Crossover rack
What is not one of the major systems of an automatic processor?
The development system
The principal purpose of the ciruclation system is to
agitate the chemistry
Which segment of the circulation system is most important to archival quality?
Fixation
Underreplenishment of the developer will result in...
a decrease in contrast
Replenishment tanks should have close-fitting floating lids primarily...
To control aerial oxidation
Dry-to-drop time refers to
Time from feed tray to receiving bin
The segment of the ciruclation system that is most likely to contain a filter is the...
developer
If the power of the drive motor is transferred through a chain, the connecting device is usually at
sprocket
Control of the replenishment system is accomplished by a...
microswtich
The approximate developer conditions in a 90-second processor are...
95 degrees F, 22 s
The transport system does not include what?
Drying chamber
The 3-inch master roller is a part of a
turnaround assembly
What artifact is associated with inadequate processing?
Pi lines
If a radiograph turns yellow during storage, this is most likely the result of what?
Incomplete washing
A radiographic image shows the central region exposed and the sides unexposed. The probable cause is...
An upside-down grid
What best describes an example of preventive maintenance?
Changing motor oil every 3000 miles
What is the limiting factor when an extremely fast image receptor is used?
noise
What is most likely to occur before processing?
A small blur on an otherwise sharp radiograph
What is the likely result of excessively high developer temperature?
Increased fog density
In a 90-second processor, immersion time in the developer is approximately...
20 s
Most facilities would be sure that the automatic processor was...
cleaned weekly.
The classification of artifacts includes all of the following, except: Exposure artifacts, Handling artifacts, Location artifacts, Processing artifacts, Storage artifacts
Location artifacts
What would be identified as a handling artifact/
Kink marks
Motion blur is usually caused by too...
long an exposure time
processor cleaning...
should be done monthly
What would be considered a storage artifact?
Radiation fog
Failure of a system or subsystem of an automatic processor will result in what?
Nonscheduled maintenance
pi lines are so called because they have what characteristics?
They occur at 3.1416-inch intervals.
What is the most distinctive and identifiable?
Pi lines
Artifacts caused by wet pressure sensitization usually occur...
in the developing tank
Where will guide shoe artifacts be found on a radiograph?
Leading and trailing edges
Archival quality is a term that refers to
long-term storage of film