WEEK 8---Film & Film Processing Flashcards by ROGER ALONSO

X-Ray Film
• Film is a media that makes a permanent record of the image.
• Image recorded on film is caused by exposure to __________

photons

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X-Ray Film Cross Section

OVERCOAT
EMULSION
ADHESIVE
BASE
ADHESIVE
EMULSION
OVERCOAT

KNOW LAYERS

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Film Construction-BASE
•Today made of a polyester plastic
–Used to be glass
•Must be clear, strong, consistent thickness
•Tinted pale blue or blue-gray
–Reduces eye strain
•Coated on 1 or 2 sides with \_\_\_\_\_\_\_\_\_

emulsion

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Film Construction-EMULSION

•Film emulsion can be on one side or both sides of base
–(single emulsion or double emulsion)
•Emulsion is the active layer of film
•Emulsion is a ________ containing the film crystals
• Protective overcoat layered on top of emulsion
*Made of mixture of gelatin & silver halide crystals
•Most x-ray film emulsions made of:
–silver _________ (98%)
–silver iodide (2%)
•Photographically active layer
–activated by light & radiation to create image

gelatin

bromide

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Light vs Dark Areas On Film

•________ areas:
–silver halide crystals that have been exposed to
photons
•turn to black metallic silver after processing

•_________areas:
–no crystals exposed
•silver halide is washed away with processing

Dark

Light

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Film Construction

• Film is manufactured to have specific characteristics of speed, contrast & resolution
• Film is also manufactured to be sensitive to specific colors of light:
– This is known as
________________________

SPECTRAL MATCHING

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Image On Film

• Single emulsion = better detail
• Double emulsion = slightly less detail
–\_\_\_\_\_  \_\_\_\_\_\_\_\_ radiation dose needed
•Parallax
–With double emulsion an image is created on both
emulsions
–then superimposed
•Results in slight blurring of edges

MUCH LESS

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Parallax

An image is created on both emulsions
–then ___________
• Results in slight blurring of edges

superimposed

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Film Types X 3

1 •__________-Film
–Most commonly used in diagnostic imaging
–Almost always double emulsion
2 •Direct-Exposure Film
–No screens used = significantly higher patient
radiation dose
3 •Other films for special applications
–Duplication, cineradiography, dental radiography

Screen

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Screen -Film has several characteristics to consider:
–contrast, speed, spectral matching and safe light
requirements.

KNOW X 4

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Film Contrast

A • Manufactured in multiple levels

1 – ______-contrast film (black-and-white image)
• Smaller crystals of uniform size

2 –________-contrast film (more shades of gray)
•Larger crystals with a wide range of sizes

High

Low

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Film Speed
•Greater efficiency = less exposure = faster
-Standard speed ≈ 100
-200 screen speed is twice as fast
• Speeds for \_\_\_\_\_\_\_ work: 200-800
• Speeds for high \_\_\_\_\_\_\_: 50-100

routine

detail

***SO KNOW THAT SLOWER = BETTER DETAIL.

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Film Speed Characteristics

1 • Single vs Double emulsion
• Double =________

2 • Size/Concentration of Crystals
• Larger, more concentrated crystals = ________

3 • Thickness of emulsion
• Thicker emulsion = _______

*** Remember that in general, the faster the speed,
the lower the patient radiation dose and the
lower the _____________________.

faster

RESOLUTION

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Film Speeds

_________ speed -reduces patient exposure
_________ speed -reduces image detail

Faster

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Film Storage

Clean, dry location, light tight location
40-60 % Humidity

KNOW X 6

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Film Handling
• Do not bend or crease
• Hands must be clean
• Film is sensitive to ________ and scratches

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pressure

X-ray Film Sensitivity
• Light
• X-rays
•Gamma Rays
•Gases
•Fumes
•\_\_\_\_\_\_\_\_\_\_\_\_
•Moisture
•Pressure
•Static Electricity
•Age

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HEAT

FILM FOG!!!!

Unintended uniform optical density on a radiograph because of x- rays, light, or chemical contamination that ___________ contrast & affects density.

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reduces

Image formation

Information on film BEFORE processing =________ image

Made visible by chemical processing

AFTER proper chemical processing = __________ image

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LATENT

manifest

_______ = The term applied to the chemical reactions

that TRANSFORM the latent image into a manifest image.

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Processing

•Film passes through:
1–Developer = Changes the silver ions of exposed crystals into metallic silver (black)
2– Fixer = Stops development and treats the film to prevent ________
3– Wash = H2O

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fading

Spectral Sensitivity Or Spectral Matching

Film is designed to be sensitive to the color of light emitted by the intensifying screens

•[Blue–UV] light sensitive film:
–CALCIUM TUNGSTATE screens

•[Green,Yellow-Green] light sensitive film:
–______ ________ screens

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RARE EARTH

Film is either blue-sensitive or green-sensitive

This is known as _____________ film
In the dark room
a. –green sensitive film MUST use a _____ filter
b. –blue sensitive film can use a red or an amber filter

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orthochromatic

red

Cassettes X 3

Cassettes serve 3 important functions:

Protect film from exposure to light.
Protect film from bending and scratching during use.
Contain intensifying screens, keeps film in close contact to screen during exposure

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KNOW X 3

Cassette Or Film Holder The cassette is used to hold the film during examinations. It consist of front and back intensifying screens, and has a _________ backing. •The cassette is light tight

lead (Pb)

Cassette Features-Front Exposure side of cassette is the front. • Made of _________ material–easily penetrated by x-rays,lightweight metal alloy or plastic material made of resin. • Intensifying screen mounted to inside of front.

radiolucent

Cassette Features -Back • Back made of metal or plastic • Inside back is a layer of _____ _______ –prevents _______________ that could fog the film • In front of the foil layer is a layer of padding –maintains good film/screen contact • Back intensifying screen mounted on padding

lead foil BACK SCATTER

Intensifying Screens • Flat surface coated with fluorescent crystals called _____________ that glow, giving off light when exposed to x-rays. • The purpose of intensifying screens is to convert x-ray photons into_________ photons • They are called intensifying screens because they greatly intensify the exposure of the film. • Using intensifying screens is one of the most important patient _______ _________ techniques in radiology.

‘phosphors’ light radiation reducing

Intensifying Screens Phosphors • RARE EARTH–(emits _______ light) –Developed in 1980’s –Most efficient –most common in use today • CALCIUM TUNGSTATE (______ light) –Older technology –Not as efficient

green blue

Intensifying Screens * The light photons generated in the intensifying screen are emitted by__________ crystals. * These crystals are significantly _________ than the silver halide crystals in the film * Use of a screen ________ image sharpness somewhat * Some examinations requiring extremely fine detail use screens with small crystals.

phosphor larger reduces

Intensifying Screens ADVANTAGES: 1. Greatly REDUCED patient exposure 2. INCREASE x-ray tube life DISADVANTAGES: 1. LESS detail than direct exposure

know these

Screen Construction ``` 1 • Polyester plastic base – support layer 2 • Reflective layer – increases screen efficiency by redirecting light headed in other directions 3 • Phosphor layer –active layer –X-ray photons converted into light photons 4 • Protective coating ```

KNOW THIS BULLSHIT | EX...SEE SLIDE 49

_________ = is when the exposure of the emulsion by light is from the opposite side of the intensifying screen • This causes increased_______ on the image ***Crossover is reduced by adding a ____ to the base

Crossover blur dye

Screen Speed * A relative number that describes how efficiently x- ray photons are converted into light. * Ranges from ___ (slow) to______ (fast) * The use of intensifying screen will increase the speed of an imaging system.

50 1200

Screen Speed • Greater efficiency = less exposure = faster - Standard screen speed ≈ 100 - 200 screen speed is twice as fast • Speeds for routine work: 200–800 • Speeds for high detail: 50–100 • Increasing speed also increases image noise •Faster speed-REDUCES patient exposure •Faster speed-REDUCES image detail and INCREASES noise (blurring)

THIS IS A REVIEW OF EARLIER SLIDES

Spatial resolution The use of intensifying screens_____ spatial resolution compared with direct-exposure radiographs. • Spatial resolution is expressed by the number of line pairs per millimeter (lp/mm)

lowers

The ______the lp/mm the smaller the object that can be imaged * Very fast screens = 7lp/mm * Fine-detail screens= 15lp/mm * Direct-exposure screens = 50lp/mm * The Human eye unaided can detect ≈ 10lp/mm

higher

SCREEN FILM "CONTACT" SEPERATION BETWEEN THE SCREEN AND FILM PRODUCES ______ SHARPNESS

LESS | ***SEE SLIDE 57

Care of Screens • Image artifacts can appear if screens are _____________or ______________________ –Dirty screens & screens with small scratches can leave artifacts • Screens should be cleaned once each month with manufacturer’s cleaner with antistatic compounds

DIRTY DAMAGED

WEEK 8---Film & Film Processing Flashcards

(39 cards)