Image receptors 2

Question 1

what are the two types of film?

Answer 1

direct action film
indirect action film

Question 2

what is direct action film used for?

Answer 2

intra-oral radiographs
peri-apical, bitewing, occlusal

Question 3

what is direct action film sensitive to?

Answer 3

x-rays

Question 4

what is indirect action film used for?

Answer 4

Extra-oral radiography e.g. DPTs, lateral ceph

Question 5

why is direct action film placed in a sealed plastic barrier when used?

Answer 5

infection control

Question 6

what are the 4 layers of a direct action film packet from outer to innermost?

Answer 6

outer layer
black paper
lead foil
direct action film

Question 7

what is the purpose of the outer layer in direct action film packet? 3

Answer 7

Sealed to protect from saliva -> keep dry

Keep film light tight to prevent fogging as photosensitive

Indicates correct orientation: one side is white which goes next to x ray machine, the bump goes at the crown of the tooth

Question 8

what is the purpose of the black paper in direct action film packet? 2

Answer 8

Protects from light leakage

Supports the film to prevent crimp/pressure marks

Question 9

what does this image show?

Answer 9

fogging due to light exposure

Question 10

the lead foil in a direct action film packet is composed of what?

Answer 10

mix of aluminium and lead

Question 11

what is the purpose of lead foil in direct action film packet?

Answer 11

Absorbs back scatter -> x-rays may hit other structures then bounce back

Has a pattern in the lead which will show if film placed wrong way

Question 12

what are the layers of direct action film from innermost to outer? 4

Answer 12

base layer of polyester plastic

adhesive layer containing anti-glare tint

emulsion layer -> silver halide (bromide) crystals in gelatine

gelatine layer

Question 13

what is the function of the adhesive layer in direct action film?

Answer 13

Stick emulsion layer to base layer

Question 14

what is the function of the emulsion layer in direct action film?

Answer 14

Reacts with the x-rays to form the image

Question 15

what is the function of the gelatine layer in direct action film?

Answer 15

protection from physical damage (super coat)

Question 16

How is the image formed in direct action film

when x-ray photons hit ??? they become sensitised and produce a ??

Not visible to naked eye but can be made visible during ?

Answer 16

silver halide crystals
latent image

processing

Question 17

what are the 2 speeds of direct action film?

Answer 17

slow = less sensitive to x-ray photons
fast = more sensitive to x-ray photons

Question 18

direct action film

The larger the crystals in the ? the ? the film speed and the ? the amount of x-rays required to produce an image

However larger crystals = ? detail = ? resolution

Answer 18

emulsion
faster
lower

less
lower

Question 19

what are the sizes for direct action film?

Answer 19

0124

Question 20

what is size 0 direct action film used for?

Answer 20

anteriors and children

Question 21

what is size 1 direct action film used for?

Answer 21

canines

Question 22

what is size 2 direct action film used for?

Answer 22

adult posterior and bitewings and children over 10

Question 23

what is size 4 direct action film used for?

Answer 23

occlusals

Question 24

what is indirect action film sensitive to?

Answer 24

light
(not x-rays so differs from direct action film)
X-rays react with intensifying screen which produces light and exposes the film

Question 25

where is the intensifying screen located in indirect film?

Answer 25

On either side of the film forming a cassette

Question 26

what are the 4 layers of an intensifying screen

Answer 26

base layer - plastic/polyester reflective layer phosphor layer super coat

Question 27

what is the function of the reflective layer in intensifying screens?

Answer 27

reflect light to film

Question 28

what is the function of the phosphor layer in intensifying screens?

Answer 28

reacts with x-rays to produce light

Question 29

what is the function of the super coat in intensifying screens?

Answer 29

protects phosphor layer from damage

Question 30

indirect action film How it works X-ray photons hit ?? in ?? and produces ? ? reflected back towards ? and reacts with ?? in ?? Crystals sensitised producing a ??

Answer 30

phosphor layer intensifying screen light light film silver halide film emulsion latent image

Question 31

indirect action film Intensifying screen is very efficient so allows a reduction in ?? however has reduction in ? as 1 x-ray photon will produce ? light photons.

Answer 31

radiation exposure resolution multiple

Question 32

Film handling It is very sensitive to ? and ?

Answer 32

pressure bending

Question 33

what is the mark on the film caused by?

Answer 33

Film handling It is very sensitive to pressure and bending

Question 34

how is the latent image made visible?

Answer 34

through processing using chemicals Reduction of the exposed silver bromide crystals to black metallic silver

Question 35

what are the 5 stages in film processing?

Answer 35

develop wash fix wash dry

Question 36

what does developing stage do in film processing?

Answer 36

make the latent image visible

Question 37

film processing -> developing Developing agents phenidone and hydroquinone act on the crystals reducing them to ??? causing the visible blackening Calcium carbonate - ? - controls the activity of the developing agents Potassium bromide - ? - stops developer working on unexposed crystals Sodium sulphite - ? - slows down oxidation Water - ? - dilutes the chemicals Action of developer is determined by: ?, ? and ? (higher = darker)

Answer 37

black metallic silver activator restrainer preservative solvent time temperature concentration

Question 38

what does the first wash stage do in film processing?

Answer 38

stop development and remove excess developer (only in manual processors)

Question 39

what does the fix do in film processing?

Answer 39

make the image permanent

Question 40

film processing -> fix Fixing agents change ??? to ?? so they can be washed away Clearing agent - ammonium thiosulphate Acidifier - acetic acid - maintains the pH and neutralises the developer Hardener - aluminium chloride Preservative - sodium sulphite Solvent - water End left with only ?, ? and ? silver halide crystals Action of fixing agents are determined by ?, ? and ?

Answer 40

unexposed silver halide soluble compound exposed developed fixed time temperature concentration

Question 41

film processing what does an underfixed image look like?

Answer 41

has a green/brown tinge

Question 42

what does the second wash in film processing do?

Answer 42

stop the fix and remove the residual fixer Remove unexposed silver halide crystals once they have been made soluble by the fixer

Question 43

what is the function of drying in film processing?

Answer 43

easier handled (not sticky) and prevent damage

Question 44

name 3 methods of film processing

Answer 44

automatic manual instant

Question 45

Health and safety COSHH - control of substances hazardous to health All manufacturers must supply Material Safety Data Sheets for potentially hazardous substances Protection: ventilation, PPE, change chemicals every 2 weeks