Introduction to Radiology Flashcards
What is the significance of Von Kolliker’s Hand
It developed cancerous lesions
Discovery of harm from X-rays
What are the considerations for X rays in the “Dose vs Diagnostic Benefit’
There must be a NEED FOR INFORMATION (cannot be gained any other way)
Consideration of the RISK OF RADIATION DOSE
Must ensure that DIAGNOSTIC YIELD/BENEFIT is as high as possible
How is the diagnostic yield/benefit dependent on
High quality imaging
Our ability to interpret looking at the images
What are the principles for radiation protection
Justification
Optimisation
Dose limitation
What is meant by justification
For every time we want to radiograph that it is justified, this is of benefit to the patient and deciding what is the right examination to do
What does optimization consist of
ALARA
ALARP
What is ALARA
As low as reasonably achievable
The principle means that even if it is a small dose, if receiving that dose has no direct benefit you should try to avoid it
What is ALARP
As low as reasonably practicable
The ALARP principle is that the residual risk shall be reduced as far as reasonable practicable
What is dose limitation
For radiation workers and members of the public, NOT patients
Why dose dose limitation not apply to patients
There is no dose limit for patients, the amount of radiographs taken is dependent on the need
How are X-rays produced
Source of X-rays is the X-ray machine, it produces the X rays
The X-rays are directed at an object (teeth and jaws) and there is an interaction of X-rays with matter
What are image receptors
Image receptors are used to capture the interaction and create an image, there are different types
What are the different types of image receptors
Digital
X-ray film packets (intra-oral)
Screen film combinations
What are different types digital receptors
direct and indirect
What are direct digital receptors
react directly with x ray photons
What are indirect digital receptors
interaction with x-ray photons is still there but there has to be another step after that to see the outcome of that
intra-oral in radiology in level 3
What are X-ray film packets used for
intra oral
They have a piece of x-ray film which directly reacted with the x-rays
Used on level 6
What is screen-film combinations used for
extraction oral
little used now
What is processing
when there is conversion of latent image to permanent visible image
How can images be processed
digitally
chemically
Where do X-rays machines get their electrical supply
domestic electric supply but require convertor
What is the range of kV for a dental machine
60-70
may be higher for some machines including panaromics
Can we sense X-rays?
No
Machine will make a sound on production because it is required to
What is the direction of travel of X-rays
From the point of origin they travel in a straight line but it is diverging so as it moves away from the point it diverges
What are the photographic properties of X-rays
This was what was discovered right back in the 19th century which enabled images to be created which could then be kept
What are the different interactions with matter
no effect
complete absorption
absorption and scatter
What are the properties of X-rays
electromagnetic radiation
straight, diverging beam
photographic
interacts with matter
What is meant if an x ray has no effect on the matter it interacts with
With some materials such as air then the x-ray may pass through without any interaction at all
What is meant if an x-ray is completely absorbed by the matter
Absorption provides an image but it also means that the radiation is transferred to the patient adding to the dose for potential harm Appears WHITE (radiopaque)
What materials completely absorb x-rays
metal fillings
What is meant by absorption and scatter
Only get partial absorption of energy in X-ray beam but individual component of the beam has its direction changed
What is the disadvantage of absorption and scatter
Going to add dose to patient but also has potential for exiting patient and if there is someone else there then it can give a dose to them
What is a radiographic image
A record of the pattern of attenuation of the X ray beam as it passes through the matter
What is attenuation
a combination of absorption and scatter events
What will the image appear as
will show different shades of grey and some white may not be seen if there are no metal restorations
What are the different dental radiographic views
intra-oral, extraoral and conebeam CT
What are the intra-oral radiographs
bitewings
peri-apicals
occlusal
What are the extra-oral radiographs
Panaromic (DPT/DPR/OPT)
Cephalometric
What does a bitewing show
the side teeth
What is the criteria for a good bitewing
Symmetry of upper and lower teeth
Minimal overlap of adjacent teeth (especially not at the ADJ)
Interdental bone
What should a bitewing demonstrate
○ Upper and lower crowns of one side
○ Mesial first premolar contact to most distal contact point or surface
○ None, or minimal, overlap of teeth
○ Enamel-dentine junction
○ Coronal pulp morphology
Interdental bone (unless a lot of bone loss)
How many bitewings should be taken per px
- Take right and left radiographs
- Take one per side unless all premolars and molars are present then 2 will be required
What is the pathology shown on bitewings
○ Interproximal caries○ Cervical caries
○ Occlusal, buccal and lingual caries
○ Restorations - ledges and defects
Interdental bone change
What does a periapical show
full length of at least one tooth
What are the surrounding anatomical features seen on a periapical
○ Inferior alveolar canal
○ Roots
Surrounding bone
What are the pathologies that can be seen on perioapicals
Crown - caries, trauma and other non-carious tooth Surface loss Changes related to restorations Pulpal pathology Root morphology Supporting bone
How is an occlusal radiograph taken
Image receptor (film packet) is put in occlusal plane
Why is an occlusal radiograph larger
image receptor is larger
What is an oblique occlusal radiograph
Gives a large ‘periapical style’ radiograph
Can be taken everywhere
What is a true (cross sectional) occlusal radiograph
○ Gives a cross sectional view of the teeth however nowadays CBCT is used over it
○ Can only be taken for lower
What is a panoramic radiograph
Full view of dentition
An image of a layer, not full thickness of all structures between X-ray source and image receptor
What is a panoramic useful for
Very useful as part of orthodontic planning, quite a common view to take for impacted wisdom teeth
Very different from intra-orals
What is a cephalometric radiographs
- View of facial bones to enable measurement of dental and skeletal relationships
- Usually lateral view (true lateral)
Includes soft tissue profile
- Usually lateral view (true lateral)
