Image Receptors 2

Question 1

what is the purpose of the films outer plastic?

Answer 1

keeps film dry, saliva free
protects film from light damage and fogging
ensures orientation is correct

Question 2

what is the purpose of the film black paper?

Answer 2

protects film from light leakage
stiffens and supports film
prevents crimp and pressure mark

Question 3

what is the purpose of the lead foil?

Answer 3

composed of mixture of lead/aluminium
readily absorbs xrays
prevents back scatter
has distinct pattern embossed in lead

Question 4

film components?

Answer 4

base - plastic - polyester 
blue antiglare tint
adhesive layer
double emulsion
protective gelatin layer

Question 5

what is in the emulsion?

Answer 5

silver halide crystals in gelatin
silver bromide/silver iodide/combo of two
gelatin allows even distribution
gelatin absorbs liquid readily allowing processing

Question 6

what is the purpose of the adhesive layer?

Answer 6

sticks emulsion to base

Question 7

what does the super coat provide?

Answer 7

additional gelatin protective layer

Question 8

how is an image produced on film?

Answer 8

xrays hit silver halide crystals in emulsion
silver halide crystal becomes sensitised
latent image produced

Question 9

what is a latent image?

Answer 9

a pattern produced in the emusion by the sensitising of the crystals by xrays
not visible to the naked eye but becomes visible by chemical reactions during processing

Question 10

what is the main reaction during processing?

Answer 10

the reduction of silver bromide crystals to black metallic silver

Question 11

what is the film speed?

Answer 11

the sensitivity of the film to the xrays

larger crystals = larger speed

Question 12

what would the dose be like for a fast film?

Answer 12

lower amount of xrays required to produce the film

Question 13

what size of crystals give reduced detail?

Answer 13

large crystals/ fast film

Question 14

what are the layers of an intensifying screen?

Answer 14

base, reflective layer, phosphor layer, supercoat

Question 15

what is the base layer made from?

Answer 15

polyester

Question 16

what happens in the phosphor layer?

Answer 16

fluorescent phopshors emit light when excited by xrays

Question 17

what is the purpose of the supercoat?

Answer 17

protects phosphor layer from damage

Question 18

what is the consequence of the reduced dose used?

Answer 18

less detail

Question 19

sequence of image production in indirect film?

Answer 19

xray hits phosphor crystal in intensifying screen and gives off light
light hits silver halide crystals in film emulstion
silver halide crystals are sensitised
latent image

Question 20

what is the light produced from the intensifying screen in proportion to?

Answer 20

directly proportional to the energy in the xray phtoton

Question 21

how to store film?

how to prevent use of old film?

Answer 21

cool dry place away from radiation

stockroom rotation

Question 22

3 methods of film processing?

Answer 22

automatic, manual, instant

Question 23

steps of processing?

Answer 23

develop - make latent image vis.
wash - remove developer from film
fix - make image permanent
wash - stop fix and remove residual layer
dry - easier handled, prevent damage

Question 24

stages in a automatic processor?

Answer 24

feed in rollers
developer rack
fixer rack
wash rack
dryer

Question 25

what stages in the automatic processor uses squeeze rollers?

Answer 25

developer rack, fixer rack, wash rack

Question 26

what happens during developing?

Answer 26

sensitised halide crystals are acted upon by developing agents, phenidore and hydroquinone reduction of silver bromide to silver +bromide

Question 27

what are the activator agents?

Answer 27

calcium carbonate - controls activity of developing agents

Question 28

what is the restrainer agent?

Answer 28

potassium bromide - stops development of unexposed crystals

Question 29

preservative agent?

Answer 29

sodium sulphite- slows down oxidation

Question 30

solvent?

Answer 30

water

Question 31

what is the temp of a developer?

Answer 31

each developer has its own optimum working temperature

Question 32

too long in developer? | too short in developer?

Answer 32

dark | light

Question 33

too hot in developer? | too cold in developer?

Answer 33

dark | light

Question 34

concentration too strong? | too weak?

Answer 34

dark | light

Question 35

what does the fixing agent do?

Answer 35

fixing agents change unexposed silver halide to soluble compound so they can washed away acid maintains the pH and neutralises the developer

Question 36

what is the cleaning agent?

Answer 36

ammonium thiosulphate

Question 37

what is the acidifier?

Answer 37

acetic acid - maintains pH

Question 38

what is the hardener?

Answer 38

aluminium chloride

Question 39

what is the preservative?

Answer 39

sodium sulphite

Question 40

an over fixed image?

Answer 40

image is removed from the film

Question 41

an under fixed image?

Answer 41

green tinge- does not archive

Question 42

when does wash happen in a manual processer? | automatic processer?

Answer 42

dev/fix, fix/dry | between fix and dry

Question 43

what does wash do?

Answer 43

stops action of developer, reduces carry over of material | removes unexposed crystals once made soluble by the fixer

Question 44

what happens when there's insufficient washing?

Answer 44

film will feel tacky green/silver appearance dont archive well - image deteriorates

Question 45

drying film reduces possibility of what?

Answer 45

damage to emulsion

Question 46

why is an automatic processor good?

Answer 46

its consistent less operator dependent temp controlled, time controlled less damage to film

Question 47

why is a manual process good | downsides?

Answer 47

done well = as good as automatic | very operator dependent, time needs to be accurate

Question 48

advantages of instant processor? | disadvantages of instant processor?

Answer 48

quick, convenient | large amount of chemicals to be disposed of, films dont archive well

Question 49

what is COSHH?

Answer 49

control of substances hazardous to health regulation

Question 50

danger with fixer?

Answer 50

corrosive and can release sulphur dioxide/ammonia on contact with strong acid/alkali

Question 51

make sure what is in place when using a processor?

Answer 51

ventilation - 10 room volumes/hour