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BDS3 CLINICAL Radiology > Digital & Film Radiography > Flashcards

Digital & Film Radiography Flashcards

1
Q

How do digital and film forms of radiography differ

A

they differ in how the x-ray beam is dealt with after it has interacted with the patient

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2
Q

What are the type of digital receptors

A

phosphor plate
solid sensor

both multiple use

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3
Q

What are the types of film receptors

A

direct action
indirect action

both single use

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4
Q

What aerate different measurements for the receptor size for phosphor plates

A

size 0 - anterior periapicals
size 2 - bitewings; posterior periapical
size 4 - occlusal radiographs

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5
Q

What is an x ray shadow

A

it is a pattern of attenuation that you see if you pass the x ray beam through an object

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6
Q

How does the x ray shadow get turned into an x ray density

A

the receptor measures the x-ray intensity at defined areas that are arranged in a grid

each area is given a value relating to x ray intensity

each value corresponds to a different shade of grey

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7
Q

What are the values relating to x ray intensity

A

range from 0-255
255 means that very few x ray photons are reaching the area

0 = black
255 = white
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8
Q

How is the digital image displayed

A

as a grid of squares called pixels

each pixel can only display one color at a time

more pixels you have the more accurate the image

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9
Q

What is the benefit of more pixels

A

better detail and a higher resolution

increasing the resolution will provide a more diagnostic image up to a limit

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10
Q

What is the issue if there’s too many pixels

A

digital image will require more storage space resulting in increased costs

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11
Q

Why are digital receptors limited in how small they can make the pixels

A

due to manufacturing challenges

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12
Q

How are radiographs typically processed in regards to greyscale bit depth

A

the radiographs are typically processed in at least 8 bits which refers to the different number of shades of grey available

you do 2^8 giving 256 meaning 256 shades of grey

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13
Q

How can a digital image be modified

A

contrast/widowing
negative
emboss
magnify

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14
Q

What is the format for digital images

A

DICOM - digital imaging & communications in Medicine

international standard format for handing digital medical images used to transmit, store, retrieve, print, process and display images

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15
Q

What are the benefits of DICOM

A

allows imaging to work between diff software, machines, manufacturers, hospitals and countries without compatibility issues

also stores other important data alongside the image

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16
Q

What is PACS

A

picture archiving and communication system

a medical imaging technology which provides storage and access to images (typically in healthcare organization)

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17
Q

What are the main components of PACS

A

input by imaging modalities e.g plain radiography, CT, MRI, US

secure network for transmission of px info

workstations for interpreting and reviewing images

archives fo rate storage and retrieval of images and reports

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18
Q

What environment should digital radiographs be viewed

A

subdued lighting

avoid glare

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19
Q

How should the monitor be prepared for viewing digital radiographs

A

should be

clean
adequate display resolution
high enough brightness level
suitable contrast level

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20
Q

What is the SMPTE test pattern

A

society of motion, picture and television engineers
available online
can be used to assess the resolution, contrast and brightness of your monitor/monitors

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21
Q

Describe phosphor plates

A

not connected to computer

after the receptor is exposed to X-rays it must be put in scanners and read to create the final image

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22
Q

Describe image creation using phosphor plates within the patients mouth

A

the receptor is exposed to the x ray beam

the phosphor crystals in the receptor are excited by the x ray energy resulting in the creation of a latent image

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23
Q

Describe image creation using phosphor plates within the scanner

A

receptor scanned by a laser

the laser energy causes the excited phosphor crystals to emit visible light

this light is detected and creates the digital image

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24
Q

What are the types of solid state sensors

A

charged couple device (CCD)

complimentary metal oxide semiconductor (CMOS)

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25
Q

Describe solid state sensors

A

connected to computer - usually wired but can be wireless

latent image created and immediately read within the sensor itself meaning final image is created virtually instantly

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26
Q

What are the components of a solid state sensor

A

black housing + cable

electronic substrate

CMOS imaging chip

fibre-optic face plate

scintillator screen

front housing

direction of the x ray beam

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27
Q

What is the point of the identification dot

A

it is located in the corner of the receptor to aid orientation of the image

only effective if the receptor was positioned correctly during exposure

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28
Q

How is cross infection control done for digital receptors

A

intra oral receptor have purpose made single use covers to prevent saliva contamination

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29
Q

What are examples of cross infection control covers

A

adhesive sealed plastic covers

long plastic sleeves

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30
Q

Why do receptors require careful handling

A

both digital and film receptors can be damaged

for digital, if certain types of damage happen they will impact every subsequent image obtained from that receptor and this reduces their diagnostic value and may render the receptor unusable

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31
Q

How should receptors be handled to prevent damage

A

hold it by their edges, not by their fault surface

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32
Q

What are types of damage you can get

A

scratches and tears
fingerprints
bending and creases

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33
Q

What are the features of phosphor plates

A

thinner, lighter and flexible

wireless so mores table and comfortable

variable room light sensitivity meaning there is risk of an impaired image

latent image needs to be processed in scanner separately

handling similar to film

34
Q

What are the features of solid state sensors

A

bulkier and rigid
usually wired
smaller active area for same physical area of recpetor
no issue with room light control
arguably more durable and so they’re replaced less often
more expensive

35
Q

What are the components of an inter oral film packet

A 
Inner paper
dental film
inner paper wrap
lead foil backing
outer package
36
Q

What is the function of the protective paper surrounding the film

A

it protects the film from light exposure, damage by fingers and saliva

37
Q

What is the function of the lead foil in the intra oral film packet

A

it absorbs some excess x ray photons

38
Q

What is the function of the outer wrapper

A

it prevents ingress of saliva

indicates which side of the packet is in the front

39
Q

What is radiographic film

A

material in which the actual image is formed

sensitive to both x ray photons and visible light photons

photons interact with emulsion on film to produce latent image which only becomes invisible after chemical processing

40
Q

What is the structure of radiographic film

A

transparent plastic base on inside
adhesive surrounding
emulsion on top
protective coating of clear gelatin

41
Q

What is the function of a transparent plastic base

A

supports the emulsion

42
Q

What is the function of the adhesive

A

attaches the emulsion to the plastic base

43
Q

Where is the emulsion

A

layered on both sides of the plastic base

44
Q

What is the function of the protective coating of clear gelatin

A

shields the emulsion from mechanical damage

45
Q

What is radiographic emulsions made of

A

it is silver halide crystals embedded in gelatin binder

crystals are microscopic and they are what become the pixels of the final image

46
Q

What are the silver halide crystals

A

usually silver bromide

they become sensitized upon interaction with x-ray (& visible light) photons

47
Q

What happens to silver halide crystals during processing

A

the sensitized crystals are converted to particles of black metallic silver and these lead to the dark parts of the image

the non sensitized crystals are removed resulting in the lighter parts of the image

48
Q

Where is the lead foil seen

A

it lies behind the film and absorbs photons behind the primary beam and also x ray photons that scatter in the patient smooth and bounce back to hit the film

49
Q

What can be seen if the receptor is put back to front

A

you see a embossed pattern as the x ray photons have to pass through the lead before the emulsion

50
Q

What is film speed

A

relates to the amount of x ray exposure required to produce an adequate image

51
Q

What does increased film speed mean

A

increased speed means reduced radiation required to achieve an image

52
Q

What is film speed affected by

A

number and size of the silver halide crystals

larger crystals have a faster film but poorer image quality

53
Q

If you change to a different film speed what must u do

A

convert settings on x-ray unit which has to be done by a qualified technician

install a filter to absorb part of the primary x ray beam

54
Q

What are intensifying screens

A

used alongside special indirect action film for extra oral radiographs

too bulky fr intra oral use

REDUCE RADIATION DOSE BUT ALSO REDUCE DETAIL

55
Q

Describe how intensifying screens work

A

the film is placed inside the cassette with an intensifying screen on either side

the screens release visible light upon exposure to x ray and this visible light creates latent image on film which can be converted using film processing

56
Q

What is film processing

A

sequence of tests which converts the invisible latent image to a visible permanent image

57
Q

Where must film processing be carried out

A

must be carried out under controlled standardized conditions to ensure consistent image quality

58
Q

What are the different methods for film processing

A

manual
automated
self developing films

59
Q

What are the common steps for film processing

A 
developing 
washing
fixing 
washing
drying
60
Q

What happens in developing

A

converts sensitized crystals to black metallic silver particles resulting in darker areas

61
Q

What happens in washing

A

removes residual developer solution

62
Q

What happens in fixing

A 
removes non sensitized crystals
hardens emulsion (which contains the black metallic silver)
63
Q

What happens in washing

A

removes residual fixer solution

64
Q

What happens in drying

A

removes water so that the film is ready to be handled/stored

65
Q

Describe what happens in the manual or wet cycle

A

person dips film into different tanks of chemicals at precise concentrations/temperatures for specific periods of time and washes the film after each tank

66
Q

Where must the manual cycle be done

A

in a dark room with absolute light-tightness and adequate ventilation

67
Q

What is the automated cycle

A

all necessary steps carried out within a machine

exposed film goes in one end and processed film comes out the other

68
Q

What is the benefits and disadvantages of the automated cycle

A

faster and more controlled than manual processing and avoids need for a dark room

more expensive

69
Q

In the automated cycle, how is the washing cycle done

A

sponge rollers squeeze developer solution of the film

70
Q

How do you open a film packet for automated processing

A

disinfect the surface of the packet and wipe off

hold the packet under the hood of the processor unit

peel back flap of outer wrapper

fold back lead foil

pull back paper flip

hold film by edges (NOT SURFACES) and slide out

insert film into processor slot/shelf

71
Q

What are the advantages of self developing films

A

no darkroom or processing facilities required

faster

72
Q

What is the disadvantage of self developing films

A

poor image quality - important

image deteriorates more rapidly over time

no lead foil - important

easily bent

difficult to use in positioning holders

relatively expensive

73
Q

What are processing issues in developing

A

it involves a chemical reaction (sensitized silver halide crystals -> black silver)

reaction affected by time, temp and solution conc

developer solution oxides in air - becomes less effective over time, needs to be replaced regularly (irrespective to how many films have been developed)

74
Q

What are the potential causes of pale image

A

exposure issue

developing issue

75
Q

What are exposure issue that can lead to a pale image

A

radiation exposure factors too low

76
Q

What are developing issues that can lead to a pale image

A

film removed from solution too early

solution too cold

solution too dilute/old

77
Q

What are issues that come form inadequate fixing

A

means non desensitised crystals are left behind

image is greenish-yellow or milky

image becomes brown over time

78
Q

What are issues that come from inadequate washing

A

developer and fixer solution will continue to act if not washed off

79
Q

What are issues with film storage

A

takes up room

needs to be easily accessible and safe from damage

requires a reliable organization system to allow images to be found easily and reduce risk of images being lost and mixed up

80
Q

What are advantages of digital radiography

A

no need for chemical prcoesinsg

easy storage and archiving of iamages

easy back up of images

images can be integrated into patients records if digital

easy transfer/sharing of iamges

images can be manipulated

81
Q

What are disadvantages of digital radiography

A

worse resolution and risk of pixelation

requires diagnosis level computer monitors for optimal viewing

risk of data corruption / loss which is solved by backing up

hard copy print outs have lower image quality

image enhancement can create misleading images

BDS3 CLINICAL Radiology (16 decks)

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