Bushong CH 12

Created by Phil_R_Conklin Plus

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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

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