Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

M4 Radiology > Image receptors 2 > Flashcards

Image receptors 2 Flashcards

1
Q

Why is there an outer plastic wrapping on films?

A

Keeps film dry – saliva free.

Protects film from light damage – fogging.

Indicates the correct orientation of the film in the mouth – white side towards x‐ray tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is there black paper in the film packet?

A

Protect film from light leakage

Stiffens & supports film. This is to prevent crimp/pressure marks on the film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is there lead foil in the film packet?

A
  • Composed of a mixture of lead and aluminium .
  • Readily absorbs x‐rays.
  • Prevents back scatter.
  • Has a distinct pattern embossed into lead.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the flim have?

A
  • Direct action.
  • Base ‐ plastic (polyester or cellulose)
  • Anti‐glare tint – blue
  • Adhesive layer
  • Double emulsion
  • Protective layer of gelatin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the layers of a dental Film?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the Emulsion layer?

A
  • Silver halide crystals suspended in gelatin.
  • Silver bromide, silver iodide or a combination of the two.
  • Gelatin allows even distribution of crystals.
  • Gelatin absorbs liquid readily to allow processing.
  • Adhesive layer “sticks” the emulsion to the base.
  • Super coat – an additional protective layer of gelatin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is the image formed?

A
  • Direct action (intra‐oral)
  • X‐ray photon hits Silver Halide crystal within emulsion of film
  • Silver halide crystal becomes sensitized
  • Latent Image
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a Latent Image?

A

It is the pattern produced within the emulsion by the sensitizing of silver bromide/iodide crystals, either by light or x-rays.

It is not visible to the naked eye but can be made so by the chemical reactions that take place during processing.

The main reaction being the reduction of the silver bromide crystals to black metallic silver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the film speed dependent on?

A
  • Dependent on the size of crystals in the emulsion.
  • Larger the crystals the faster the film speed.
  • Faster the film speed the lower the amount of x‐rays required to produce an image.
  • Larger crystals = reduced detail
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a Direct action film and an Indirect action film?

A

Direct Action Film (Intra‐oral)

Indirect Action Film (Extra‐oral)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an Indirect Film?

A
  • Indirect film
  • Sensitive primarily to light
  • Light produced by intensifying screens inside the cassette.
  • The light produced is in direct proportion to the x‐rays that hit the screens.
  • Reduces exposure required to produce image and therefore the dose received by patient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a Intensifying Screen?

A
  • Base – polyester.
  • Reflective layer.
  • Phosphor layer ‐ fluorescent phosphors, emit light when excited by x‐rays. T
  • he light produced is in direct proportion to the energy in the x‐ray photon.
  • Supercoat – protects phosphor layer from damage

Allow a reduction in exposure and therefore a reduced dose to patient BUT Reduction in detail in image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is an image formed in Indirect Action?

A

Indirect action (extra‐oral)

  • X‐ray photon hits phosphor crystal in intensifying screen.
  • Gives off light.
  • Light hits Silver Halide crystal within film emulsion.
  • Silver halide crystal becomes sensitized.
  • Latent Image
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where do you store film?

A

Cool – not too cool

Dry – not too dry

Away from radiation – x‐rays, heat.

Stock rotation to prevent using old film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the stages of film processing?

A
  • Develop – make latent image visible
  • Wash – stop development and remove dev from film [only in manual processing]
  • Fix – make image permanent.
  • Wash – stop fix and remove residual fixer
  • Dry – easier handled, prevent damage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does the film Develop?

A
  • Sensitized silver halide crystals (silver bromide/iodide) are acted on by the developing agents phenidone and hydroquinone which involves the chemical reduction of silver bromide to silver plus bromide
  • Silver is in the form of black metallic silver
  • Thus giving the blackening on the film
17
Q

What is in the Developer?

(Developing agents, activator, restrainer, preservative and solvent)

A

Developing agents ‐ Phenidone & Hydroquinone

Activator ‐ Calcium carbonate (controls the activity of the developing agents)

Restrainer ‐ Potassium bromide (stops developer working on unexposed crystals)

Preservative ‐ Sodium sulphite (slows down oxidation)

Solvent ‐ Water

18
Q

What is The action of the developing agents on the silver halide crystals is very dependant on?

A
  1. Time: Too long ‐ dark. Too short ‐ light.
  2. Temperature: Too hot ‐ dark. Too cold ‐ light.
  3. Concentration: Too strong ‐ dark. Too weak ‐ light
19
Q

What is film processing?

A

THE REDUCTION OF THE EXPOSED SILVER BROMIDE CRYSTALS TO BLACK METALLIC SILVER AND THEN MAKING THIS IMAGE PERMANENT

20
Q

What is the Developer?

A

making the image visible

21
Q

What is the fixer?

A

Making the image pernament

22
Q

What does the fixing agents do and what is in a Fixer?

A
  • The fixing agents change unexposed silver halide to soluble compound so they can be washed away.*
  • Acid maintains the pH and neutralize the developer.*

Clearing agent ‐ Ammonium thiosulphate

Acidifier ‐ Acetic acid (maintains pH)

Hardener‐ Aluminium chloride

Preservative ‐ Sodium sulphite

Solvent ‐ Water

23
Q

What is The action of the fixing agents on the silver halide crystals is very dependant on?

A

Time, temp, concentration?

Not as critical as developer but if over fixed image will be removed from film.

Under fixed will appear to have green tinge and will not archive well.

24
Q

When do you wash?

A

Manual ‐ between dev and fix and between fix and dry.

Stops action of developer and reduces carryover

Remove unexposed silver halide crystals once made soluble by fixer

Automatic ‐ only between fix and dry

Remove unexposed silver halide crystals once made soluble by fixer

25
Q

What are the different methods of film processing?

A

AUTOMATIC

  • Consistent
  • Less operator dependant
  • Temperature controlled
  • Time controlled
  • Less chance to damage film

MANUAL

  • Very operator dependant
  • Done well can be as good as automatic.
  • Temp must be monitored
  • Time must be accurate

INSTANT

  • Chemicals in pouch attached to film
  • Very quick
  • No large amount of chemicals to be disposed of
  • Convenient
  • Films do not archive well
26
Q

What does COSHH stand for in health and safety?

A

CONTROL OF SUBSTANCES HAZARDOUS TO HEALTH

27
Q

What is the adequate ventilation for recommended handling?

A

Adequate ventilation ‐ 10 or more room volumes per hour

M4 Radiology (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions