Module 3 & 4 : Image Recording and Storage Devices Flashcards
(47 cards)
1
Q
three reasons why having a recording device is important
A
- radiologist/cardiologist is not always present
- required for teleradiography
- images can be used for comparison
2
Q
7 ways to record images
A
- multiformat cameras
- laser imagers
- color thermal printers
- fibre-optic recorders
- video thermal printers
- video tape recording
- computer storage
3
Q
what was the most common means of storing a hard copy of images
A
- film
4
Q
what are the three different types of film
A
- transparency film (negative)
- polaroid film (positive)
- paper film
5
Q
what was the most common type of film used and why
A
- transparency film
- several years of shelf life and infinite resolution
6
Q
disadvantages of film
A
- storage space
- ease of retrieval for viewing
- cost
- chemicals
7
Q
how is transparency film constructed
A
- in layers with an acetate base toped with an emulsion layer that contains silver bromide crystals and a suspension gelatine
- light strikes the crystal to form the latent image and are converted to silver grains with chemical processing
8
Q
with film how are the images made darker
A
- exposure to light increases more silver grains are activated and the darker the image becomes
9
Q
what is film speed
A
- how fast it darkens
10
Q
what two things must be matched to the monitor used for exposure
A
- film speed
- contrast
11
Q
how long did it take to manually process transparency film
A
- 1 hour per film
12
Q
4 steps to automatic processing
A
- development
- fixing
- washing
- drying
13
Q
how long does it take to automatically process film
A
- 1-2 minutes
14
Q
disadvantage to transparency film
A
- variations in density/contrast of processing
- use of chemicals was also expensive and caustic to the environment
- takes a long time
15
Q
what is the multiformat camera
A
- one of the most common devices used to expose transparency film
- essentially a CRT that could fix an image onto the film
- has excellent gray scale and used a shutter and a lens to control the exposure time and position
16
Q
disadvantages to multiformat camera
A
- CRTs have curved screens which could distort the image
- high quality lens increases cost
- one camera per machine
- dust and movement
17
Q
what replaced the multiformat camera
A
- the laser camera
18
Q
what does laser stand for
A
L- light A - amplification by S - stimulated E - emission of R - radiation
19
Q
why are the intensity and size of the laser beam controlled
A
- to improve contrast and detail resolution
20
Q
could more than one machine/modality use one laser camera
A
- yes
21
Q
was the film used by laser camera sensitive or insensitive to light
A
- insensitive
22
Q
what does laser camera film contain
A
- laser sensitive carbon layer that when activated by heat cause the carbon to stick and the back can be peeled off
23
Q
what is polaroid film
A
- requires no special processing
- relatively inexpensive
- spatial resolution poor
24
Q
how did the black and white polaroid film work
A
- exposure to light creates white on the film using silver halide crystals
25
what are the three layers of color polaroid film
- RGB that are activated with exposure
26
what is the video thermal printer
- fairly good quality but not as good as the multi format or laser printer
27
how does a video thermal printer work
- video signal is stored in the memory and transferred to a thermal printing mechanism
- the heat sensitive paper is then passed along a mechanism and the heat creates a gray scale where the shade of gray corresponds to the amount of heat produced
28
what was one of the biggest problems for video thermal printer
- archival stability
| - could not place exposed film near a heat source or image would degrade over time
29
what is the color video printer
- similar to video thermal printer
- uses dye on paper
- if no dye is present then paper is white and RGB together make black
- printing requires single pass of each color which increases printing time
30
what is a magnetic tape recording
- used a lot
| - gave ability to capture a video as opposed to a still picture
31
what is the format of the cassette for magnetic tape recorder and what were they played on
- video home system (VHS)
| - video cassete recorder (VCR)
32
what is a super VHS (SVHS)
- better spatial resolution and used in more hospitals
33
how does a magnetic tape recorder work
- contains magnetic dipoles that can be aligned in a magnetic field where the strength of the signal determines the alignment
34
how is the tape played back
- tape passed through a red head and the fluctuating magnetic field produces a video signal
- an audio track can also be included in sync
35
what is the spatial resolution of a VHS
- 240 lines
36
what is the spatial resolution of a SVHS
- 200 lines
37
can both VHS and SVHS be played on both VHS machines and SVHS machines
- VHS machines = VHS only
| - SVHS = VHS and SVHS
38
what are magneto-optic disks
- combined two technologies
+ magnetic and optics
- large memory space and rewritable
- not susceptible to magnetic damage
39
how are the MO disks created
- laser heats the disk past its currie point so the magnetic crystals can be realigned when placed in a. magnetic field
40
how were the MO disks read
- a weaker laser scatter the light off the disk and the intensity is read to create the signal
41
one advantage and disadvantage to MO disks
- could hold hundreds of MB
| - lack of compatible drives
42
what does PACS stand for
P - picture
A - archiving
C - communication
S - system
43
6 advantages to pacs
- storage
- external viewing
- connection to other modalities
- web access
- image quality
- time factor
44
how does a pacs system work
- electronically transfers digital data from a machine to a workstation
- with the internet images could be sent anywhere
45
what was a challenge with pacs and how was it solved
- manufacturers all use different programming and coding to digitize there images
- set a universal standard for compressing images called DICOM
46
what does DICOM stand for
D - digital
I - imaging
CO - communications in
M - medicine
47
disadvantages to pacs
- large cost investment (but eventually pays off)
| - complexity of equipment and the additional backup require additional staff for upkeep and maintenance
