Dental Radiology

Front 1

5 Reasons to take a bitewing?

Back 1

1. Detect caries
2. Monitor caries progression
3. Assess restorations
4. Monitor bone levels
5. Other pathology ie impacted teeth

Front 2

12 Properties of X-rays?

Back 2

1. Invisible, longitudinal waves of the EMS that travel as photons
2. Ionising
3. No charge
4. Travel at speed of light
5. Travel in straight lines
6. Damage/kill/mutate cells
7. Effect silver halides
8. Produces photofluorescence in some materials
9. Produced by electrons impacting on matter
10. Shorter wavelength than visible light
11. Emitted at a continuous spectrum - Shortest wavelength determined by tube voltage
12. Differentially absorbed

Front 3

What does BERT stand for? Give an example of it's use.

Back 3

Background Equivilant Radiation Time
1 transatlantic flight = 5 days BERT

1 Chest X-ray = 4 days BERT

PA with E speed film:
Round Collimator: 8 hours BERT
Square Collimator: 4 hours BERT

Front 4

What are the occupational limits on radiation dose?

Back 4

20mSv/year over 5 years with no more that 50mSv in any one year

Front 5

What is the ALARA principle?

Back 5

As Low As Reasonably Achievable

Front 6

How can ALARA be achieved?

Back 6

Lead aprons
Minimsing errors and retakes
Fast speed film (F)
Collimator (square best)
Aluminium filter
Safe distance/Barrier to next worker
Low use of rooms surrounding X-ray room
Timer

Front 7

What does the collimator do?

Back 7

Remove peripheral x-rays therefore minimsing dose to patient. Square is best

Front 8

What does the Aluminium filter do?

Back 8

Remove low wavelength x-rays that would only be absorbed by the patient (increase mean wavelength). This reduces dose.

Front 9

What are the pros of the Parallel technique?

Back 9

Less likely to cone cut
Maxilla and Zygomatic arch doesn't get in the way
No size distortion

Front 10

What are the cons of the Parallel technique?

Back 10

Can't do it everywhere - upper molars, palate in way
More uncomfortable for patient
Apices near edge of film
Film further from tooth therefore poorer image definition

Front 11

What are the pros of the Bitewing technique?

Back 11

Easier
More comfortable for the patient
Adequete for diagnosis, if not ideal

Front 12

What are the cons of the Bitewing technique?

Back 12

Not reproducible
Bone levels poorly shown
Image distortion of the root/crown. Makes caries diagnosis difficult

Front 13

What is SLOB?

Back 13

Same Lingual Opposite Buccal

These are the directions that the said teeth will move in relation to the X-ray TUBE when it is moved.

Front 14

What is the Buccal Object rule?

Back 14

The buccally located object will move in the same direction as the X-ray BEAM

Front 15

What is the 90/Different Planes of Ref method?

Back 15

Taking 2/3 radiographs from different angles to localise an object

Front 16

What film sizes are used for bitewings?

Back 16

Size 0 = children
Size 1 = mixed dentition
Size 2 = adults

Front 17

What film sizes are used for periapicals?

Back 17

Size 0/1 = Vertically placed for anteriors
Size 2 = Horizontally placed for posteriors

Front 18

What can/should be seen on a bitewing?

Back 18

Occlusal plane should be in the middle
Equal amounts of Max/Man crown and roots
Target teeth shown completely
1/3 of Alveolar bone crest
Surrounding tissue

Front 19

How should an image appear?

Back 19

Good sharpness, clarity and contrast
No staples etc covering diagnostic areas
No fingerprints
Minimum distortion
Faults/artifacts no in diagnostic ares
No conecut
No overlap in critical areas

Front 20

Why should you take periapicals? (10)

Back 20

1. Assess periodontal status
2. See root morphology pre-extraction
3. Trauma cases
4. Pre/post op assesment for endodontic treatment
5. Bone assesment for implants
6. Position/prognosis of implant
7. Assessment of apical lesion
8. Assessment of impacted teeth
9. Assessment of lesions on Aveolar bone
10. Assess apical changes due to infection/inflammation

Front 21

What can/should be seen in a periapical?

Back 21

Crown and root of target teeth
3-4mm Apically of tooth
Surrounding tissue

Front 22

What interaction produce X-rays?

Back 22

Braumstralung: X-rays produced via electron/nucleus interaction

Electron to Electron

Front 23

What are the steps in image processing?

Back 23

Developing - Converts exposed silver halide crystals (which contain silver ions) to metallic silver, softens gel emulsion. 4.5 minutes at 20 degrees

Rinsing - 15/20 seconds

Fixing - Halt development, remove undeveloped silver halide, harden gel emulsion

Washing - remove thiosulphates that would otherwise turn the film brown, 10 minutes

Drying

Front 24

Constituants of developer? (SHEPS)

Back 24

DEVELOPER
Reducing agents that donate electrons to silver ions
Elon - Brings out shades of grey quickly. Temp independant
Hydroquinone - Gives contrast slowly. Temperature sensitive

ACTIVATOR
Sodium Carbonate - softens gelatin and maintains alkaline conditions

RESTRAINER
Potassium Bromide - Delays developer effect, reduces fog

PRESERVATIVE
Sodium sulphite - Prevents oxidation of Developer

Developer must be completely changed every 3-4 weeks

Front 25

Constituants of fixer? (SAPS)

Back 25

FIXER
Sodium Thiosulphate - interacts with silver halide making it water soluble and therefore removable

ACIDIFIER
Acetic Acid - Neutralisers residual alkali therefore stoping development. Provides necessary acidic environmnet for hardener

HARDENER
Al Potassium Sulphate - hardens gel emulsion

PRESERVATIVE
Sodium Sulphite - prevents oxidation of residual Developer

Front 26

What is the dental film made of?

Back 26

Base - hard gelatin, tinted slightly blue

Emulsion - gelatin matrix embedded with silver bromide crystals and some silver iodide crystals and sulphur.

Front 27

Voltage from Cathode to Anode effects what? What is the usual voltage?

Back 27

Wavelength/energy of rays. Higher voltage gives higher energy/ shorter wavelength waves

50 to 90 kV

Front 28

Current in the tungsten coil effects what?

Back 28

High current give high number of electrons in wire, therefore x-ray number.

Front 29

Give some errors that cause faulty radiographs?

Back 29

Cone cutting - incorrect beam/film allignment
Insuffient exposure time
Light leakage (film fog)
Too light - underdeveloped
Too dark - overdeveloped
Patient movement
Processing errors: temperature, time, depleted/diluted developer or fixer

Front 30

What is mSv?

Back 30

milli Sievert
Sievert = unit of dose equivalent to 1 J/Kg

Front 31

What are the milliSeivet values for the usual radiographs taken?

Back 31

PA & Bitewings: 1-2 mSv (square vs round collimator)

OPG: 3.4 mSv

Chest film: 30 mSv