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X-RAY PHYSICS MIDTERM 2 > WEEK 8---Film & Film Processing > Flashcards

WEEK 8---Film & Film Processing Flashcards

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1
Q

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

A

photons

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2
Q

X-Ray Film Cross Section

OVERCOAT
EMULSION
ADHESIVE
BASE
ADHESIVE
EMULSION
OVERCOAT
A

KNOW LAYERS

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3
Q 
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 \_\_\_\_\_\_\_\_\_
A

emulsion

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4
Q

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

A

gelatin

bromide

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5
Q

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

A

Dark

Light

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6
Q

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
________________________

A

SPECTRAL MATCHING

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7
Q

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
A

MUCH LESS

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8
Q

Parallax

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

A

superimposed

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9
Q

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

A

Screen

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10
Q

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

A

KNOW X 4

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11
Q

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

A

High

Low

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12
Q 
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
A

routine

detail

***SO KNOW THAT SLOWER = BETTER DETAIL.

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13
Q

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 _____________________.

A

faster

faster

faster

RESOLUTION

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14
Q

Film Speeds

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

Faster

Faster

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15
Q

Film Storage

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

KNOW X 6

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16
Q

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

A

pressure

17
Q 
X-ray Film Sensitivity
• Light
• X-rays
•Gamma Rays
•Gases
•Fumes
•\_\_\_\_\_\_\_\_\_\_\_\_
•Moisture
•Pressure
•Static Electricity
•Age
A

HEAT

18
Q

FILM FOG!!!!

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

A

reduces

19
Q

Image formation

Information on film BEFORE processing =________ image

Made visible by chemical processing

AFTER proper chemical processing = __________ image

A

LATENT

manifest

20
Q

_______ = The term applied to the chemical reactions

that TRANSFORM the latent image into a manifest image.

A

Processing

21
Q

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

A

fading

22
Q

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

A

RARE EARTH

23
Q

Film is either blue-sensitive or green-sensitive

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

orthochromatic

red

24
Q

Cassettes X 3

Cassettes serve 3 important functions:

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

KNOW X 3

25
Q

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

A

lead (Pb)

26
Q

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.

A

radiolucent

27
Q

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

A

lead foil

BACK SCATTER

28
Q

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.

A

‘phosphors’

light

radiation reducing

29
Q

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

A

green

blue

30
Q

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.
A

phosphor

larger

reduces

31
Q

Intensifying Screens

ADVANTAGES:

  1. Greatly REDUCED patient exposure
  2. INCREASE x-ray tube life

DISADVANTAGES:
1. LESS detail than direct exposure

A

know these

32
Q

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
A

KNOW THIS BULLSHIT

EX…SEE SLIDE 49

33
Q

_________ = 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

A

Crossover

blur

dye

34
Q

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.
A

50

1200

35
Q

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)

A

THIS IS A REVIEW OF EARLIER SLIDES

36
Q

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)

A

lowers

37
Q

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
A

higher

38
Q

SCREEN FILM “CONTACT”

SEPERATION BETWEEN THE SCREEN AND FILM PRODUCES ______ SHARPNESS

A

LESS

***SEE SLIDE 57

39
Q

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

A

DIRTY

DAMAGED

X-RAY PHYSICS MIDTERM 2 (4 decks)

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