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BDS3 Radiology > Digital and film radiography > Flashcards

Digital and film radiography Flashcards

1
Q

What X ray receptors are used in dentistry for digital radiographs?

A
  • phosphor plate
  • solid-state sensor
    all can be used multiple times
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2
Q

What X ray receptors are used in dentistry for film radiographs?

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

outline how X-ray shadows are converted to images

A
  • when x-ray beam passes through an object some of the x-ray photons are attenuated. creating an x-ray shadow
  • x-ray shadow contains ‘information’ held by the x-ray photons after an x-ray beam has passed through an object
  • image receptor detects this x-ray shadow and uses it to create an image
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4
Q

Image creation using phosphor plates within the patients mouth

A
  • receptor exposed to x-ray beam
  • phosphor crystals in receptor excited by x-ray energy
  • results in creation of a latent image
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5
Q

Image creation using phosphor plates within the scanner

A
  • receptor scanned by laser
  • laser energy causes excited phosphor crystals to emit visible light
  • which is detected and creates an image
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6
Q

phosphor plates properties

A
  • thinner, lighter and usually flexible
  • wireless
  • variable room light sensitivity - risk of impaired image
  • latent image needs to be processed separately in scanner
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7
Q

Advantages and disadvantages of solid state sensors

A
  • bulkier and rigid
  • usually wires
  • smaller active area
  • no issues with room-light control
  • moe durable = replaced less often
  • more expensive
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8
Q

function of lead foil in intra-oral film packet

A

absorbs excess x-ray photons

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9
Q

Function of protective black paper in intra-oral film packet

A

protects film from light exposure, damage by fingers and saliva

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10
Q

function of outer wrapper in intra-oral film packet

A
  • prevents ingress of saliva
  • indicates which side of packet is in the front
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11
Q

constituents of an intra-oral film packet

A
  • lead foil
  • protective black paper
  • outer wrapper
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12
Q

What is radiographic film?

A
  • material in which the actual image os formed
  • sensitive to x-ray and visible light photons
  • photons interact with emulsion on film producing latent image which becomes visible after chemical processing
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13
Q

outline the structure of radiographic film

A
  • transparent plastic base
  • adhesive
  • emulsion
  • protective coating of clear gelatine
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14
Q

Function of radiographic emulsion in radiographic film

A
  • contains silver halide crystals in a gelatine binder
  • crystals effectively become ‘pixels’ of the final image
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15
Q

Properties of silver halide crystals

A
  • usually silver bromide
  • become sensitised upon interaction with x-ray and visible light photons
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16
Q

what happens to silver halide crystals during processing?

A
  • sensitised crystals are converted to particles of black metallic silver (dark parts of final image)
  • non-sensitised crystals are removed and form the light parts of final image
17
Q

Outline the steps of film processing

A
  • developing
  • washing = removing residual developer solution
  • fixing = removal of non-sensitised crystals - hardens emulsion
  • washing = removes residual fixer solution
  • drying = removes water to allow handling and/or storage of film
18
Q

Advantages of self-developing films

A
  • no darkroom or processing facilities required
  • faster - approx. 1 minute
19
Q

disadvantages of self-developing films

A
  • poorer image quality
  • image deteriorates over time
  • no lead foil
  • easily bent
    = relatively expensive
20
Q

Advantages of digital radiography

A
  • no need for chemical processing
  • images can be stored and archived easily
  • easy back-up of images
  • images can be integrated into patient records
  • easy transfer and sharing
  • images can be manipulated
21
Q

Disadvantages of digital radiographs

A
  • worse resolution
  • requires diagnostic level computer monitors for optimal viewing
  • image enhancement can create misleading images
  • hard copy print-outs generally have lower image quality
22
Q

developing issues with film radiographs

A
  • involves chemical reaction, which is affected by time, temperature and solution concentration
  • developer solution oxidises in air, making it less effective over time
23
Q

Potential causes of pale film radiograph image

A
  • radiation exposure factors too low
  • film removed from solution too early
  • solution too cold
  • solution too dilute
24
Q

potential film processing issues in fixing stage

A
  • involves chemical reaction which removes non-sensitised crystals and hardens remaining solution
  • inadequate fixing means some remain
  • greenish-yellow or milky image
  • become brown over time

BDS3 Radiology (9 decks)

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