Digital and Film and Radiography

Question 1

digital vs film receptors
times they can be used

Answer 1

digital - multi use
film - single use

Question 2

Greyscale bit depth

Answer 2

number of different shades of grey available
radiographs usually 8 bits - 2^8 = 256 shades of grey

Question 3

How are digital receptors arranged

Answer 3

arranged in a grid with the squares of grid known as pixels
more pixels = more accurate image (higher resolution) up to a point*
each pixel can only display one colour
pixels measure intensity of beam (number of photons) reaching it with different intensities corresponding to different shades of grey

Question 4

what effect does increased pixels have on file size and therefore storage (digital radiography)

Answer 4

increased pixels = increased file size = increased storage space required

Question 5

what does PACS stand for

Answer 5

picture archiving and communication system

Question 6

what are the 2 types of digital inta oral receptors

Answer 6

phosphor plates
solid state sensors

Question 7

phosphor plate receptors

Answer 7

used in digital intra oral radiography
they are not connected to anything and must be ran through a separate scanner to create an image
within the patients mouth a latent image is created on the receptor, within the scanner a laser is used to convert this to a digital image

Question 8

solid state sensors

Answer 8

used in digital intra oral radiography
connected to the computer - usually via wire but can be wireless
latent image created on the receptor is immediately read and an image produced on the computer

Question 9

solid state sensors vs phosphor plates
price

Answer 9

solid state are more expensive

Question 10

solid state sensors vs phosphor plates
impact of light

Answer 10

phosphor plate receptors may be damaged by light

Question 11

solid state sensors vs phosphor plates
patient comfort

Answer 11

phosphor plate receptors thinner, less bulky and less rigid
also wireless

Question 12

what is contained within a radiographic film receptor packet

Answer 12

radiographic film - on which actual image is formed
lead foil , lies behind film , to absorb excess photons

Question 13

what 2 types of photons are x ray film sensitive to

Answer 13

x ray photons
visible light photons

Question 14

how is a latent image created on film radiography

Answer 14

film contains silver halide crystals which become sensitised upon interaction with x ray photons
must be chemically processed to become visible - sensitised crystals are converted to particles of black metallic silver

Question 15

what is the impact on having large silver halide crystals on a film rather than small

Answer 15

larger crystals results in faster production and therefore decreased patient dose however the image is of poorer quality

Question 16

what are the 5 stages of film developing

Answer 16

developing
washing
fixing
washing
drying

Question 17

what is done during the developing stage of film developing

Answer 17

sensitised crystals are converted to black metallic silver particles

Question 18

what is done during the washing stages of film developing

Answer 18

removes residual developer and fixer solution

Question 19

what is done during the fixing stage of film developing

Answer 19

removes non sensitised crystals

Question 20

what is done during the drying stage of film developing

Answer 20

removes water so film can be stored

Question 21

digital vs film radiography

Answer 21

digital requires no chemical processing, has easier storage, images can easily be manipulated and added to digital patient records
however they are of poorer resolution and risk data corruption
on the whole digital are superior

Question 22

what would happen to the x ray image if developer solution was old and out of date (film radiography)

Answer 22

less silver halide crystals would be converted so the image would be lighter

Question 23

what would happen if the developer solution was too warm or too concentrated (film radiography)

Answer 23

more silver halide crystals would be converted so the image would be darker

Question 24

what would happen if there was inadequate fixation of an image (film radiography)

Answer 24

decreased contrast of image as excess crystals not removed

Question 25

what would happen if film was exposed to visible light before processing

Answer 25

darker image would be produced as more crystals sensitised as film sensitive to both x ray photons and visible light photons