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PHYS 314 > Image Recording & Storage Devices > Flashcards

Image Recording & Storage Devices Flashcards

1
Q

Why are recording devices important?

A
  1. Rad is not always present
  2. Required for teleradiography
  3. Images can be used for later comparison
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2
Q

What are the types of film that can be used to capture images? (3)

A
  1. Transparency film
  2. Polaroid film
  3. Paper film
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3
Q

Are polaroids and transparency film positive or negative?

A 
Transparency = Negative
Polaroid = Positive
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4
Q

What was the most common type of recording medium and why?

A

Transparency film

  1. Several year shelf life
  2. Infinite resolution
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5
Q

What are the disadvantages of film? (4)

A
  1. Storage space
  2. Ease of retrieval for viewing
  3. Cost
  4. Not environmental
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6
Q

How is film constructed?

A

Layers with an acetate base topped with an emulsion layer that contains silver bromide crystals and a suspension of gelatin that is porous to liquids

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7
Q

How does film work?

A

Light strikes the crystals to form the latent image and are converted to silver grains via chemical processing

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8
Q

How does a film image become darker?

A

As the exposure to light increases more silver grains are activated (image becomes darker)

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9
Q

What is film speed?

A

How fast the film darkens

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10
Q

What must film speed and contrast be matched to?

A

The monitor that is used for exposure

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11
Q

How is film quality ensured?

A

Regular testing

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12
Q

How was film processed historically and how long did it take?

A

Manually

1 Hour per film

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13
Q

What were the steps processing of film?

A
  1. Development
  2. Fixing
  3. Washing
  4. Drying
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14
Q

What were the disadvantages of film processing?

A
  1. Variations in density/contrast of processing
  2. Chemicals were expensive
  3. Chemicals were not environmental
  4. Time to process
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15
Q

What is a multi-format camera?

A

One of the most common devices used to expose transparency film, essentially a CRT that could fix an image onto the film

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16
Q

What were the advantages of a multi-format camera?

A
  1. Excellent grayscale

2. Used a shutter and lens to control the exposure time and position

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17
Q

How fast was automatic processing of film and how was it done?

A

Rollers move the film through the steps in 1-2 mins

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18
Q

What was important about processing film from a multi-format camera?

A

The film was sensitive to light and had to be processed in a dark room with “wet” processing.

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19
Q

What were the disadvantages of the multi-format camera starting with the biggest? (4)

A
  1. One camera per machine
  2. CRT’s have curved screens which could distort the image
  3. High quality lens was needed and expensive
  4. Dust
  5. Bumping wrecked alignment
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20
Q

What replaced the multi-format camera?

A

The laser camera

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21
Q

What is laser an acronym for?

A

Light Amplification by Stimulated Emission of Radiation

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22
Q

What was improved with the laser camera? (Advantages)

A
  1. Intensity and size of beam are precisely controlled to improve contrast and detail resolution
  2. Many machines/modalities could be accommodated with one camera
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23
Q

Was the film for laser cameras sensitive to light?

A

No

24
Q

How did the laser camera film work?

A

The film contains a laser sensitive carbo layer that when activated by heat cause the carbon to stick and the back can be peeled off

25
Q

What was the advantage to polaroid film?

A
  1. No special processing

2. Inexpensive

26
Q

What was the disadvantage to polaroid film?

A

Poor spatial resolution

27
Q

How did b&w polaroid film work?

A

The exposure to light created white on the film using silver halide crystals

28
Q

How did the colour polaroid film work?

A

The film had 3 layers (RGB) that were activated with exposure

29
Q

How did the video thermal printer compare to the multi-format or laser printer?

A

Good quality but not as good

30
Q

How did the video thermal printer work?

A

A video signal is stored in the memory and transferred to a thermal printing mechanism, the heat sensitive paper is passes along the mechanism and the heat creates gray scale

31
Q

What does the gray scale correspond to in a video thermal printer?

A

The shade of gray corresponds to the amount of heat produced

32
Q

What was the advantage to the video thermal printer?

A

Images were available instantly

33
Q

What were the disadvantages to the video thermal printer? (3)

A
  1. Big issue with archival stability
  2. Exposed film could not be placed by any heat source
  3. Image degraded over time
34
Q

How did the colour video printer work?

A

Similar to video thermal, used a dye on paper. No dye = white, mix of RGB = black.

35
Q

What was the disadvantage of colour video printer?

A

The printing requires a single pass of each colour which increased the printing time

36
Q

What did the magnetic tape recorder allow?

A

Ability to capture video instead of just a still image

37
Q

What was the format of the magnetic tape recorder?

A

VHS (Video Home System)

38
Q

What were the VHS tapes from the magnetic tape recorder played in?

A

VCR (Video Cassette Recorder)

39
Q

What type of VHS was preferred and why?

A

S-VHS (Super VHS) because it had better spatial resolution.

40
Q

How did the magnetic tape recorder work?

A

The tape contains magnetic dipoles that can be aligned in a magnetic field where the strength of the signal determines the alignment

41
Q

How were the magnetic tape recorder tapes played back?

A

The tape is passed by the “read head” and the fluctuating magnetic field produces a video signal

42
Q

What was an advantage to the magnetic tape recorder?

A

An audio track could be included in sync with the video signal

43
Q

What was the difference in spatial resolution between the VHS and the S-VHS?

A 
VHS = 240 lines on the monitor
SVHS = 400 lines (greater spatial resolution)
44
Q

How did the playback differ between VHS and SVHS?

A

Both VHS and SVHS could be played in a SVHS machine but SVHS could not be played in a VHS which posed compatibility issues

45
Q

How were magneto-optic disks different?

A

They combined two technologies (magnetics and optics)

46
Q

What were the advantages to magneto-optic disks? (3)

A
  1. Relatively large memory space
  2. Were rewritable
  3. Not susceptible to magnetic damage
47
Q

How were magneto-optic disks used to record?

A

A laser heats the disk part its Curie point so that the magnetic crystals can be realigned when placed in a magnetic field

48
Q

How were magneto-optic disks read?

A

A weaker laser scatters light off the disk and the intensity is read to create the signal

49
Q

What was a disadvantage to magneto-optic disks?

A

They could hold hundreds of MB but suffered with a lack of compatible drives

50
Q

What is PACS an acronym for?

A

Picture Archiving Communication System

51
Q

What are the advantages of PACS? (6)

A
  1. Storage
  2. External viewing
  3. Connection to other modalities
  4. Web access
  5. Image Quality
  6. Time factor (no processing)
52
Q

How does PACS work?

A

Digital data is electronically transferred from a machine to a work station and can be sent anywhere in the world via the internet

53
Q

What was the challenge of PACS?

A

The manufacturers all used different programming and coding to digitize their images.

54
Q

What is DICOM?

A

Digital Imaging and Communications in Medicine is the universal standard in compressing images

55
Q

What did DICOM allow?

A

The images from any machine (by any manufacturer) to be sent to the workstations for tech and physicians to access

56
Q

What are the disadvantages to PACS? (2)

A
  1. Large investment (but saves cost of film/chemicals/etc.)

2. The complexity of the equipment requires additional staff to upkeep, maintain and troubleshoot.

PHYS 314 (5 decks)

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