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BDS3 Radiology > Digital & Film Radiography > Flashcards

Digital & Film Radiography Flashcards

1
Q

What are the different types of digital receptor?

A
  • phosphor plate
  • solid state sensor
  • all multiple use
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2
Q

What are the different types of film receptor?

A
  • direct action film
  • indirect action film
  • all single use
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3
Q

What are the 3 different sizes of phosphor plates and what are they used for?

A
  • size 0
    • anterior periapicals
  • size 2
    • bitewings
    • posterior periapicals
  • size 4
    • occlusal
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4
Q

What values given to x-ray intensity create black and white on a receptor?

A
  • 0 = black
  • 255 = white
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5
Q

What are the advantages and disadvantages of increasing the number of pixels on a digital radiograph?

A
  • advantages
    • better detail
    • higher resolution
  • disadvantages
    • more storage space required
    • increased cost
    • manufacturing challenges concerning smaller pixels
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6
Q

What is the typical greyscale bit depth?

A
  • 8 bits
    • 256 shades of grey
  • 8 bit is the minimum
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7
Q

What is the format for digital images?

A
  • DICOM
    • digital imaging and communications in medicine
    • also stores patient ID, exposure settings, date of image
  • international standard for handling digital medical images
    • used to transmit, store, retrieve, print, process and display
    • works between different software, machines, hospitals
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8
Q

How are digital images managed?

A
  • PACS
    • picture archiving and communication system
  • medical imaging technology
    • provides storage and access to images
    • input by imaging modalities
    • secure network for transmission of patient information
    • workstations for interpreting and reviewing images
    • archives for the storage and retrieval of images/reports
  • vary in size and scale
    • hospital PACS are not connected to dental practices
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9
Q

In what ways can digital radiographs be altered?

A
  • contrast/windowing
    • darker areas darker
    • lighter areas lighter
  • negative
    • flipping covers
  • emboss
    • makes areas of contrast stand out
  • magnify
    • focus on area of interest
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10
Q

How should digital radiographs be viewed?

A
  • environmental
    • subdued lighting
    • avoid glare
  • monitor
    • clean
    • adequate display resolution
    • high enough brightness level
    • suitable contract level
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11
Q

What is SMPTE test pattern?

A
  • society of motion picture and television engineers
    • available online
  • used to assess resolution, contrast and brightness of monitor
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12
Q

What are phosphor plates?

A
  • also called:
    • photostimulable phosphor plate
    • storage phosphor plate
  • not connected to computer
  • after receptor is exposed to x-rays it must be put in a scanner
    • read to create the final image
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13
Q

How are images created using phosphor plates?

A
  • within patient’s mouth
    • receptor exposed to x-ray beam
    • phosphor crystals in receptor excited by x-ray
    • creation of latent image
  • within scanner
    • receptor scanned by a laser
    • laser energy causes excited phosphor crystals to emit visible light
    • light is detected and creates digital image
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14
Q

What are solid-state sensors?

A
  • two types
    • CCD (charge-coupled device)
    • CMOS )complimentary metal oxide semiconductor)
  • connected to computer
    • usually wired
    • some wireless now available
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15
Q

How are images created using solid state sensors?

A
  • latent image created
    • immediately ready within sensory
    • final image created virtually instantly
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16
Q

What are the components of solid-state sensors?

A
  • back housing and cable
  • electronic substrate
  • CMOS imaging chip
  • fiberoptic faceplate
  • scintillator screen
  • front housing
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17
Q

What are identification dots?

A
  • located in corner of receptor to aid orientation of image
    • helps with orientation of image
    • ensures image has not been flipped
  • only effective if receptor was positioned correctly during exposure
    • should be on the top right or left
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18
Q

How is cross-infection control managed in digital radiography?

A
  • intra-oral receptors have purpose made covers to prevent saliva contamination
    • single-use covered
  • phosphor plates
    - adhesive sealed plastic covers
  • solid state sensors
    - long plastic sleeves
  • receptors additionally disinfected between uses
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19
Q

How is cross-infection control managed in digital radiography?

A
  • intra-oral receptors have purpose made covers to prevent saliva contamination
    • single-use covered
  • phosphor plates
    - adhesive sealed plastic covers
  • solid state sensors
    - long plastic sleeves
  • receptors additionally disinfected between uses
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20
Q

What digital receptors are used for extra-oral radiology?

A
  • larger phosphor plates
  • larger solid state sensors
    • usually build into machine
21
Q

What digital receptors are used for extra-oral radiology?

A
  • larger phosphor plates
  • larger solid state sensors
    • usually build into machine
22
Q

How should receptors be handled?

A
  • held by edges
    • not flat surfaces
23
Q

What are common types of damage to receptors?

A
  • scratches
  • tears
  • fingerprints
  • bending
  • creasing
24
Q

What are common types of damage to receptors?

A
  • scratches
  • tears
  • fingerprints
  • bending
  • creasing
25
Q

Compare phosphor plates and solid state sensors

A
  • phosphor plates
    • thinner, lighter and usually flexible
    • wireless, more stable and more comfortable
    • variable room-light sensitivity
    • risk of impaired image
    • latent image needs to be processed in scanner
    • handling similar to film
  • solid state sensors
    • bulkier and rigid
    • usually wired
    • smaller active area for same physical area of receptor
    • no issues with room-light control
    • arguably more durable
    • replaced less often
    • more expensive
26
Q

What does an intra-oral film packet contain?

A
  • inner paper
  • dental film
  • inner paper wrap
  • lead foil backing
  • outer package
27
Q

What is the function of protective paper in intra-oral film packets?

A
  • protects film
    • light exposure
    • damage by fingers
    • saliva
28
Q

What is the function of lead foil in intra-oral film packets?

A
  • lies behind film
  • absorbs some excess x-ray photons
    • primary beam continuing past the film
    • scattered by patient’s tissues, returning back to film
  • embossed pattern to highlight if receptor was placed wrong way round
    • texture shown on image
    • image will also be pale
29
Q

What is the function of the outer wrapper in intra-oral film packets?

A
  • prevents ingress of saliva
  • indicates which side of the packet is the front
30
Q

What are the properties of the radiographic film in an intra-oral film packet?

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
    • produces latent image
    • only visible after chemical processing
  • structure
    • transparent plastic base
      - supports the emulsion
    • adhesive
      - attaches emulsion to plastic base
    • emulsion
      - layered on both sides of plastic base
    • protective coating of clear gelation
      - shields emulsion from mechanical damage
31
Q

What is the emulsion of a radiographic film made of and how does it work?

A
  • silver halide crystals embedded in a gelatine binder
    • usually silver bromide
  • microscopic crystals that become ‘pixels’ of image
  • become sensitised upon interaction with x-ray photons
    • sensitised crystals converted to particles
      - black metallic silver
      - dark parts of final image
    • non-sensitised crystals removed
      - light parts of final image
32
Q

What is film speed?

A
  • relates tp the amount of x-ray exposure to produce an adequate image
  • higher the speed, the less radiation required to achieve an image
  • affected by number and size of silver halide crystals
    • larger crystals require a faster film
      - poorer image quality
33
Q

How are film speeds adjusted?

A
  • qualified technician converts settings on x-ray unit
  • filter installed to absorb part of primary x-ray beam
    • prevents over-exposure
34
Q

What are intensifying screens?

A
  • used alongside special indirect action films for extra oral
    • too bulky for intraoral use
  • recude radiation dose
    • also reduce detail
      - excitation within screen disperses energy
  • screens release visible light to create latent image on film
35
Q

What is film processing?

A
  • sequence of steps which converts the invisible latent image to a visible permanent image
  • must be carried our under controlled, standardised conditions to ensure consistent image quality
36
Q

What are the different methods of film processing?

A
  • manual
  • automated
  • self-developing film
37
Q

What are the common steps in film processing?

A
  • developing
    • converts sensitised crystals to black metallic silver particles
  • washing
    • removes residual developer solution
  • fixing
    • removes non-sensitised crystals
    • hardens emulsion (contains black metal silver)
  • washing
    • removes residual fixer solution
  • drying
    • removes water so film can be handled and stored
38
Q

What is the manual cycle?

A
  • person dips film into different tanks of chemicals
    • precise concentrations and temperatures
    • specific periods of time
    • washes film after each tank
  • must be carried out in dark room
    • adequate light-tightness (red light)
    • adequate ventilation
39
Q

What is the automated cycle?

A
  • all necessary steps carried out in machine
  • faster and more controlled than manual processing
    • avoids need for dark room
    • more expensive
  • 4 compartments
    • developer
    • fixer
    • wash
    • dryer
  • sponge rollers squeeze developer solution out of film
    - instead of washing with water
40
Q

How are film packets opened for automated processing?

A
  • disinfect surface of the packet
  • hold the packet under the hood of the processor unit
  • peel back flat of outer wrapper
  • fold back lead foil
  • pull back paper flap
  • hold film by edges and slide out
  • insert film into processor
41
Q

What are self-developing films?

A
  • radiographic film and processing solution in same packet
    • squeeze solution into film once exposed
  • not recommended
  • advantages
    • no dark-room or processing facilities required
    • faster
      - around 1 minute
  • disadvantages
    • poorer image quality
    • no lead foil
    • image deteriorates more rapidly over time
    • easily bent
    • difficult to use in positioning holders
    • relatively expensive
42
Q

Why can developer solution cause issues?

A
  • developer solution oxidises in air
    • becomes less effective over time
    • needs to be replaced regularly
      - irrespective of how many films have been developed
43
Q

What are potential causes of a pale image?

A
  • exposure issue
    • radiation exposure too low
  • developing issue
    • film removed from solution too early
    • solution too cold
    • solution too dilute/old
44
Q

What are the potential causes of a dark image?

A
  • exposure issue
    • radiation exposure too high
  • developing issue
    • film left in solution too long
    • solution too warm
    • solution too concentrated
45
Q

What issues can arise as a result of inadequate fixing?

A
  • inadequate fixing means non-sensitised crystals are left
    • image greenish-yellow or milky
    • image becomes brown over time
46
Q

What issues can arise as a result of inadequate washing?

A
  • developer and fixer will continue to act if not washed off
47
Q

What are the challenges of film storage?

A
  • takes up room
  • needs to be easily accessible and safe from damage
  • requires a reliable organisation system
    • allows images to be easily found
    • reduces risk of images being lost/mixed up
48
Q

Compare digital and dilm radiography

A
  • advantages of digital radiography
    • no need for chemical processing
    • easy storage and archiving of images
    • easy back-up of images
    • images can be integrated into patient records
    • easy transferring/sharing of images
    • images can be manipulated
  • disadvantages of digital radiography
    • worse resolution/risk of pixelation
    • requires diagnostic-level computer monitors to optimally view
    • risk pf data corruption/loss (solved by backing up)
    • hard copy print outs generally have reduced image quality
    • image enhancement can create misleading images

BDS3 Radiology (11 decks)

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