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BDS3 Radiology > Digital and Film Radiography > Flashcards

Digital and Film Radiography Flashcards

1
Q

what is the difference between film and digital radiography

A

they differ in how the x-ray beam acts after it interacts with the patient
digital radiography receptors are reusable whereas film are not

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2
Q

what x-ray receptors are used for digital radiography

A

phosphor plate
solid state sensor

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3
Q

what are the types of film receptors

A

direct action film
indirect action film

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4
Q

what size receptor is used for anterior periapicals

A

size 0

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5
Q

what size receptor is used for bitewings and posterior periapicals

A

size 2

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6
Q

what size receptor is used for bitewings and posterior periapicals

A

size 2

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7
Q

what size receptor is used for occlusal radiographs

A

size 4

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8
Q

what is an x-ray shadow

A

pattern of attenuation after passing through the object

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9
Q

how is x-ray shadow converted to a digital image

A

the receptor measures the x-ray intensity at defined areas (arranged in a grid) and then each wee box in the squarer is given its own value relating to x-ray intensity which then corresponds to a specific shade of grey

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10
Q

what are pixels

A

the grids of square in a receptor
each pixel can only display one coloiur

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11
Q

what gives a higher resolution

A

more pixels

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12
Q

why do we want a higher resolution

A

provides a more diagnostic image but only up to a limit

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13
Q

why can using more pixels potentially be a problem

A

when you increase pixels you increase storage size on computer which is increased costs

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14
Q

what is the greyscale depth

A

number of different shades of grey available

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15
Q

how many shades of grey are processed in radiographs

A

8 bits

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16
Q

what is the real number of shades available for radiography

A

256 (2 to the power of 8) goes from 0-255

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17
Q

what is a massive advantage of digital radiography

A

you can manipulate the image (make it bigger, rotate, change contrast)

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18
Q

what is embossing

A

contrast stands out more easier

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19
Q

how are digital images stored

A

DICOM - digital imaging and communications in medicine - universally acceptable

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20
Q

what other information is stored in DICOM

A

patient ID
exposure settings
date of image

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21
Q

how are digital images managed

A

PACs
picture archiving and communication system

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22
Q

what are not part of PACs

A

dental practices - you would need to email the dental hospital as a GDP to get them

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23
Q

what are the main components of PACs

A

input by imaging modalities
secure network for transmission of patient information
workstations for interpreting and reviewing images

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24
Q

what should the environment be like when viewing digital radiographs

A

subdued lighting
avoid glare

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25
Q

what is the SMPTE test pattern

A

something you can download from the internet asses the resolution, contrast and brightness of your monitor

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26
Q

what are the two types of digital intra-oral receptor

A

phosphor plates
solid state sensors

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27
Q

are phosphor plates connected to the computer

A

no

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28
Q

what is the process for using phosphor plates

A

after the receptor is exposed to x-rays it needs to be put in a scanner and read to create the final image

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29
Q

how are images created using phosphor plates

A

the receptor is exposed to an x-ray beam and the phosphor crystals in the receptor are excited by the x-rays resulting in the creation of the latent image

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30
Q

how are images created after the phosphor receptors are placed in the scanner

A

the receptor is scanned by a laser
the laser causes the excited phosphor crystals to emit visible light
light is detected and creates the digital image

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31
Q

what are the two types of solid-state sensors

A

CCD (charge coupled device)
CMOS (complimentary metal oxide semiconductor)

32
Q

are solid state sensors connected to the computer

A

yes usually by a wire

33
Q

how is the image created using solid state sensors

A

the latent image is created immediately and read within the sensor itself

34
Q

what are the two disadvantages of solid state sensors

A

more expensive
more bulky

35
Q

what is the identification dot

A

small dot which is on corner of receptor that will be on the actual radiograph and helps to re-orientate the image

36
Q

hoe are intra-oral receptors protected by cross-infection control

A

they are concealed by single use covers to prevent saliva contamination

37
Q

what happens to the receptor between uses

A

disinfected

38
Q

what damage might scratches and tears appear as on an x-ray receptor image

A

white lines

39
Q

what might bending or creasing a receptor cause in the final image

A

distortion

40
Q

what are benefits of phosphor plates

A

thinner
lighter
usually flexible
wireless

41
Q

what are the benefits of solid state sensors

A

more durable so you replace less often
no issues with room-light control

42
Q

what is in the middle of the radiographic film packet

A

radiographic film

43
Q

what is around the radiographic film

A

protective black paper which protects from light exposure, damage and saliva

44
Q

what sits under the radiographic film

A

lead foil which absorbs some excess x-ray bea,

45
Q

what covers the whole film packet

A

outer wrapper which protects from saliva

46
Q

how do images process on x-ray film

A

the film is sensitive to x-ray photons and visible light photons and the photons interact with the emulsion on film to produce latent image which only becomes visible after chemical processing

47
Q

what is the structure of a radiographic film

A

transparent plastic base
an adhesive that attaches emulsion to top and bottom of the plastic base
around which is a protective coating of clear gleatin

48
Q

what are embedded in the emulsion layer

A

silver halide crystals embedded in a gelatin binder

49
Q

what effectively become the pixels of the final film image

A

the silver halide crystals

50
Q

why do film images give higher resolution than digital

A

as the silver halide crystals are microscopic and they are what work as the pixels

51
Q

what occurs to the silver halide crystals when processing

A

they are converted into particles of black metallic silver which give the dark parts of final image and the non-sensitised crystals are removed which gives the light areas

52
Q

what is the purpose of the lead foil in the film

A

absorbs excess x-ray photons - those in primary beam continuing past film and those scattered by patients tissues

53
Q

how can you tell on film radiography if you have placed the receptor the wrong way round

A

the lead foil is embossed with a pattern which appears on the final image

54
Q

what does film speed relate to

A

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

55
Q

what is film speed affected by

A

number and size of silver halide crystals

56
Q

what does an increased film speed mean

A

decreased radiation required to achieve an image

57
Q

what must you do if changing to a different film speed

A

convert settings on x-ray unit by a qualified technician
install a filter to absorb part of the primary x-ray beam

58
Q

what are intensifying screens

A

you can reduce radiation dose but also get less detail

59
Q

why is there less detail in intensifying screens

A

because the screen makes the photons spread out to a larger area so instead of a pinpoint accurate image they are larger

60
Q

what are the different methods of film processing

A

manual
automated
self developing

61
Q

what are the five steps of film processing

A

developing
washing
fixing
washing
drying

62
Q

what occurs in the developing stage of film processing

A

converts sensitised crystals to black metallic silver particles

63
Q

what occurs in washing stage of film processing

A

removes residual developer solution

64
Q

what occurs in the fixing stage of film processing

A

removes non-sensitised crystals
hardens emulsion

65
Q

what occurs in the second washing stage of film processing

A

removal of fixer solution

66
Q

what occurs in the drying stage of film processing

A

removes water so film can be handled/ stored

67
Q

what is the manual cycle

A

person dips film into different tanks of chemicals at precise concentrations and temperatures

68
Q

what is the automated cycle

A

all necessary steps carried out in a machine

69
Q

what are self developing films

A

longer cover on it, the chemicals are kept in one end are squeezed down to meet the film - but NOT recommended

70
Q

what is the chemical reaction that turns sensitised silver halide crystals to black crystals controlled by

A

time
temperature
concentration

71
Q

what might cause a pale image

A

exposure issue (too low)
developing solution (too cold, too old)

72
Q

what is fixing

A

a chemical reaction which removes non-sensitised crystals and hardens remaining emulsion

73
Q

what might show on an image if there has been inadequate fixing

A

the image will be greenish-yellow or milky
image becomes brown over time

74
Q

how are film radiographs stored

A

reliable organisation system

75
Q

advantages of digital radiography

A

no chemical processing
easier to store and archive
easy transferring and sharing of images

76
Q

disadvantages of digital radiography

A

worse resolution
requires diagnostic level computer monitors
data corruption or loss

BDS3 Radiology (9 decks)

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