Radiographic Interpretation & CBCT images Flashcards
What following features should we look at when interpreting a radiograph
- symmetry
- margins
- bone consistency
- dentition
- supporting bone
- other features
What are we looking at when looking at margins
- is it well defined or ill defined
What else do we look at when assessing a well defined margin
- is it corticated or is it non-corticated
What do we look at when looking at a radiopaqueness
- Increased density e.g cortical bone
- Increased thickness e.g overlaps
- Alteration e.g soft tissue calcification
- Soft tissue/liquid within air space
What other features do we look at
radiolucency/radiopaque
size, site, shape
aetiological relationship
effect on other structures
What does a well corticated lesion point to
A corticated margin means it has to keep remodelling so means it is a slow growing lesion
What do we mean when looking at site, size, shape
Site = teeth, alveolus, basal bone, other bones, extra osseous
Shape = circular, oval, unilocular (one obvious lesion which is simple) , multilocular (scalloped margin or internal divisions), irregular
Size = may indicate length of time
What are the possible effect on other structures
- no effect
- displacement
- expansion
- resorption
What does displacement indicate
Indicates something is growing slowly because the bone has to remodel to be able to move teeth
What does expansion indicate
Indicates slow growing because bone has to remodel
What does resorption indicate
- Indicates aggressive as body cannot set up response to this
What type of beam does CT use
- Uses a flat, fan shaped x-ray beam
How does CT scan work
In CT, the radiographic film is replaced by very sensitive crystals or gas detects and these detectors measure the intensity of the x-ray beam emerging from the patient and convert this into digital da
How does CT scan produce slices
- Each set of detectors produces an attenuation or penetration profile of the slice of the body to be examined and then the patient is moved further up the gantry and another slice is is imaged and so on until imaging of that part of the body is complete
What are the main indications for CT
o Investigation of intracranial disease including tumours, haemorrhage and infarcts
o Investigation of suspected intracranial and spinal cord damage following trauma to the head and neck
o Assessment of fractures involving:
o Assessment of site, size and extent of cysts, giant cells and other bone lesions
o Assessment of disease within the paranasal air sinuses
o Tumour staging – assessment of the site, size and extent of tumours, both benign and malignant affecting:
o Investigation of tumours and tumour-like discrete swellings both intrinsic and extrinsic to the salivary glands
o Investigations of osteomyelitis
o Investigations of the TMJ
o Pre-operative assessment of maxillary and mandibular alveolar bone height and thickness before inserting implants
How does CBCT differ from CT
- Field of view varies, can be small (dentoalveolar), medium (maxfax), large (craniofacial)
- Employs a cone shaped x-ray beam
- Uses a special detector and the scanning/image creation process is divided into 3 stages
What are the 3 stages of CBCT
- data acquisition
- primary reconstruction
- secondary reconstruction
What are the main indications of CBCT
o Implant planning
o Impacted teeth (normal and supernumerary)
o Pathology – cystic lesions, infections, benign tumours
o Orthognathic surgery
o Hypodontia (implant planning)
o Cleft palate – bone defects
o Dental abnormalities – dilaceration, double teeth
o Endodontic problems (external cervical resorption v useful)
o Autotransplantation
What principles guide our use of CBCT
EADMFR: basic principles for use of CBCT
What are the most important principles
6, 8, 9, 10
What is principle 6
CBCT should only be used when the question for which imaging is required cannot be answered adequately be lower dose conventional (traditional) radiography
What is principle 8
Where it is likely that soft tissue evaluation will be required as part of px radiological assessment, the appropriate imaging should be conventional CT or MRI
What is principle 9
CBCT equipment should offer a choice of volume sizes and examinations must use the smallest that is compatible with the clinical situation if this provides less radiation dose to the patient
What is principle 10
Where CBCT equipment offers a choice of resolution, the resolution compatible with adequate diagnosis and the lowest achievable dose should be used
