Image Recording & Storage Devices

Question 1

Why are recording devices important?

Answer 1

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

Question 2

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

Answer 2

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

Question 3

Are polaroids and transparency film positive or negative?

Answer 3

Transparency = Negative
Polaroid = Positive

Question 4

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

Answer 4

Transparency film

1. Several year shelf life
2. Infinite resolution

Question 5

What are the disadvantages of film? (4)

Answer 5

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

Question 6

How is film constructed?

Answer 6

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

Question 7

How does film work?

Answer 7

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

Question 8

How does a film image become darker?

Answer 8

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

Question 9

What is film speed?

Answer 9

How fast the film darkens

Question 10

What must film speed and contrast be matched to?

Answer 10

The monitor that is used for exposure

Question 11

How is film quality ensured?

Answer 11

Regular testing

Question 12

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

Answer 12

Manually

1 Hour per film

Question 13

What were the steps processing of film?

Answer 13

1. Development
2. Fixing
3. Washing
4. Drying

Question 14

What were the disadvantages of film processing?

Answer 14

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

Question 15

What is a multi-format camera?

Answer 15

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

Question 16

What were the advantages of a multi-format camera?

Answer 16

1. Excellent grayscale

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

What replaced the multi-format camera?

Answer 20

The laser camera

Question 21

What is laser an acronym for?

Answer 21

Light Amplification by Stimulated Emission of Radiation

Question 22

What was improved with the laser camera? (Advantages)

Answer 22

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

Question 23

Was the film for laser cameras sensitive to light?

Answer 23

No

Question 24

How did the laser camera film work?

Answer 24

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

Question 25

What was the advantage to polaroid film?

Answer 25

1. No special processing | 2. Inexpensive

Question 26

What was the disadvantage to polaroid film?

Answer 26

Poor spatial resolution

Question 27

How did b&w polaroid film work?

Answer 27

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

Question 28

How did the colour polaroid film work?

Answer 28

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

Question 29

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

Answer 29

Good quality but not as good

Question 30

How did the video thermal printer work?

Answer 30

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

Question 31

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

Answer 31

The shade of gray corresponds to the amount of heat produced

Question 32

What was the advantage to the video thermal printer?

Answer 32

Images were available instantly

Question 33

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

Answer 33

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

Question 34

How did the colour video printer work?

Answer 34

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

Question 35

What was the disadvantage of colour video printer?

Answer 35

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

Question 36

What did the magnetic tape recorder allow?

Answer 36

Ability to capture video instead of just a still image

Question 37

What was the format of the magnetic tape recorder?

Answer 37

VHS (Video Home System)

Question 38

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

Answer 38

VCR (Video Cassette Recorder)

Question 39

What type of VHS was preferred and why?

Answer 39

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

Question 40

How did the magnetic tape recorder work?

Answer 40

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

Question 41

How were the magnetic tape recorder tapes played back?

Answer 41

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

Question 42

What was an advantage to the magnetic tape recorder?

Answer 42

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

Question 43

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

Answer 43

``` VHS = 240 lines on the monitor SVHS = 400 lines (greater spatial resolution) ```

Question 44

How did the playback differ between VHS and SVHS?

Answer 44

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

Question 45

How were magneto-optic disks different?

Answer 45

They combined two technologies (magnetics and optics)

Question 46

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

Answer 46

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

Question 47

How were magneto-optic disks used to record?

Answer 47

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

Question 48

How were magneto-optic disks read?

Answer 48

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

Question 49

What was a disadvantage to magneto-optic disks?

Answer 49

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

Question 50

What is PACS an acronym for?

Answer 50

Picture Archiving Communication System

Question 51

What are the advantages of PACS? (6)

Answer 51

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

Question 52

How does PACS work?

Answer 52

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

Question 53

What was the challenge of PACS?

Answer 53

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

Question 54

What is DICOM?

Answer 54

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

Question 55

What did DICOM allow?

Answer 55

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

Question 56

What are the disadvantages to PACS? (2)

Answer 56

1. Large investment (but saves cost of film/chemicals/etc.) | 2. The complexity of the equipment requires additional staff to upkeep, maintain and troubleshoot.