2.1 - Intro to Dental Radiology Flashcards
What must we balance in terms of radiographs (3)?
the need for info
radiation dose
diagnostic yield/benefit
What are the 3 principles of radiation protection?
Justification
Optimisation
Dose limitation
How do we justify if a pt needs a radiograph?
Does the give additional required clinical information that will benefit the pt? or can we dx without
What is optimisation?
This is when we consider ALARP - as low as reasonably practicable - this means that the dose we give to the pt is as low as it can be taking into account potential constraints such as What
What is dose limitation for?
Workers and general public - not the pt
What 3 things do we need to produce a radiographic image?
SOURCE OF X-RAY
OBJECT - TEETH AND JAWS
IMAGE RECEPTOR (can be digital or film)
What is a latent image?
One that is not yet visible and must be converted to permanent image via computer or film using chemicals
What is processing?
This is where we convert latent image to permanent visible image via digital or chemical means
What electricity supply do x-ray machines use?
60-70kV
What are some properties of x-rays? (4)
X-rays are ELECROMAGNETIC RADIATION
They travel as a straight diverging beam
photographic
interacts with matter
What is the inverse square law?
This is where x-ray beam is inversely proportion to the square distance from the source - so if we stand back from source of radiation by 1/2 it quarters the dose to radiologist
if we stand back 1/4 it will 1/8th the dose
What happens if x-rays have no effect?
This means x-ray beams pass straight through with no interaction (ie through air) and image appears black
What happens if x-rays are completely absorbed?
the material completely absorbs the photons and as a result appear white
What happens when x-rays are absorbed and scattered?
This is when there is partial absorption of the x-ray beam but individual components have had a directional change and can exit the pt
What is a radiographic image a record of?
The pattern of attenuation of the x-ray beam after it has passed through matter
What types of dental radiographic views do we have?
Bitewings
PAs
Occlusal
Panoramic
Cephalometric
What are bitewings used for?
To show the U+L pre molars and molars (ideal BW goes from medial of 8 to distal of 4) and should show symmetry of upper and lower teeth with minimal overlap of adjacent teeth (to allow for detection of caries)
What will the ideal bitewing show? (6)
- upper and lower crowns of one side
- medial first pre molar to most distal contact point or surface
- no to minimal overlap of teeth
- enamel dentine junction
- coronal pulp morphology
- ID bone unless lots of bone loss
What can bitewings detect? (5)
IP caries
cervicle caries
O,B,L caries
restorations - ledges and defects
ID bone changes over time
What are PAs?
These are used to show the full length of at least one tooth and bone levels
If we are doing an XLa what must we see in radiograph?
roots
surrounding bone
canal
What can PAs detect?
crown - caries, trauma and nc tooth surface loss
change to restos
pulpal pathology
root morphology
surrounding bone levels
What are occlusal radiographs?
An occlusal radiograph is a radiograph designed to be placed between the occlusal surfaces of the teeth with the central beam directed at 90o or at 50 -60o to the plane of the film depending on what is required to be viewed.
What extra-oral radiographs can we take?
OPT - good for ortho tx planning and showing impacted wisdom teeth
Lateral cephalometric - used to view facial bones and analyse skeletal and dental relationships and look at soft tissue profile
