Radiology - Image Receptor 2

Question 1

What does the outer plastic wrapping do?

Answer 1

Keeps film dry (saliva).
Protects film from damage (fogging).
Indicates correct orientation of film - white side towards the x-ray tube

Question 2

What does black paper do?

Answer 2

Protects the film from light leakage, stiffens and supports the film

Question 3

What does lead foil do?

Answer 3

Readily absorbs x-rays, prevents back scatter

Question 4

What does film do?

Answer 4

Direct action, adhesive layer, protective layer of gelatin

Question 5

Layers present in dental film?

Answer 5

Emulsion, super-coat, adhesive layer and base

Question 6

What does the adhesive layer do?

Answer 6

“Sticks” emulsion to the base

Question 7

Image formation process for direct action…

Answer 7

Direct action. X-ray photons hits silver halide crystals within emulsion of film. Silver halide crystal becomes sensitized resulting in latent image

Question 8

Latent image formation for direct action…

Answer 8

Silver halide crystals sensitized by x-ray photons and awaiting processing to make visible.

Question 9

What does the speed of film depend on?

Answer 9

Size of crystals in emulsion.

Lager the crystals, faster the film speed

Question 10

What do larger crystals results in?

Answer 10

Reduced details

Question 11

Indirect film are..

Answer 11

Sensitive to light. Light produced by intensifying screen inside the cassette. Light produced is in direct proportion to xray that hits the screen. Reduced exposure required to produce image and therefore dose received by patient.

Question 12

What are the layers in intensifying screen?

Answer 12

Base.
Reflective layer.
Phosphor layer.
Supercoat.

Question 13

What does phosphor layer do?

Answer 13

Fluorescent phosphors.

Emits light when excited by xrays

Question 14

Supercoat layer is responsible for?

Answer 14

Protect phosphor layer from damage

Question 15

Image formation of indirect action..

Answer 15

Extra-oral. Xray photon hits phosphor crystal in intensifying screen. Gives off light. Light hits silver halide crystal within the film emulsion. SHC becomes sensitized producing latent image.

Question 16

Stages of film processing..

Answer 16

i) Develop - make latent image visible.
ii) Wash - Stop development
iii) Fix - make image permanent
iv) Wash - Stop fix and remove residual fixer
v) Dry - easier handled, prevent damage.

Question 17

Components of automatic processor..

Answer 17

Feed in rollers, Developer rack, Fixer rack, Wash rack, Dryer.

Question 18

Process of developing?

Answer 18

Sensitized silver halide crystals acted on by the developing agents phenidone and hydroquinone. Involves chemical reduction of silver bromide to silver plus bromide.
Silver is form of black metallic silver.. giving the blackening on film

Question 19

What are the developing agents?

Answer 19

Phenidone & Hydroquinone

Question 20

Activator of developer?

Answer 20

Calcium carbonate (controls activity of developing agent)

Question 21

Restrainer of developer?

Answer 21

Potassium bromide (stops developer working on unexposed crystals)

Question 22

Preservative of developer?

Answer 22

Sodium sulphite (slows down oxidation)

Question 23

Solvent of developer?

Answer 23

Water

Question 24

What does each developer have?

Answer 24

Has its optimum working temperature

Question 25

3 factors affecting action of developing agent on silver halide crystals are?

Answer 25

i) Time: Too long (dark). Too short (light)
ii) Temperature: Too hot (dark). Too cold (light)
iii) Concentration: Too strong (dark). Too weak (light)

Question 26

How does fixing make image permanent?

Answer 26

Fixing agent change unexposed silver halide to soluble compound so they can be washed away. Acid maintains pH & neutralize developer.

Question 27

What is the cleansing agent for fixer?

Answer 27

Ammonium thiosulphate

Question 28

Acidifier for fixer?

Answer 28

Acetic acid (maintains pH)

Question 29

Hardener for fixer?

Answer 29

Aluminium chloride

Question 30

Preservative for fixer?

Answer 30

Sodium sulphite

Question 31

Solvent for fixer?

Answer 31

Water

Question 32

What does the action of fixing agent on silver halide crystals depends on?

Answer 32

If over fixed - image removed from film.

If under fixed - appear green tinge and will not archive well.

Question 33

When does manual wash occur?

Answer 33

Occurs between develop and fix and between fix and dry. Stop action of developer and reduce carryover. Remove unexposed silver halide crystals once made soluble by fixer.

Question 34

When does automatic wash occur?

Answer 34

Only between fix and dry. Remove unexposed silver halide crystals once made soluble by fixer.

Question 35

What does insufficient washing leads to?

Answer 35

Film feels tacky.
Appear green/silver.
Image will deteriorate.

Question 36

What does drying reduces?

Answer 36

Possibility of damage to emulsion.

Question 37

Automatic - method of film processing properties

Answer 37

Consistent.
Less operator dependent.
Temp & time controlled.
Less chance to damage film.

Question 38

Manual - method of film processing properties

Answer 38

Operator dependent.

Temp monitored and time must be accurate.

Question 39

Instant - method of film processing properties

Answer 39

Very quick.
Chemicals in porch attached to film - no large amount of chemicals disposed off.
Convenient.

Question 40

Steps of correct processing

Answer 40

i) Develop - correct density of image.
ii) Fix & wash - good archiving
iii) Dry

Question 41

COSHH is…

Answer 41

Control of Substances Hazardous to Health

Question 42

Chemical constituents..

Answer 42

Acetic acid.
Hydroquinone.
Phenidone.
Sodium sulphite, etc

Question 43

What are some of the potential health effects?

Answer 43

Skin sensitisation.
Allergic.
Asthma.
Persistent cough.
Headaches.