Cone Beam CT Flashcards
What is cone beam computed tomography?
A form of cross-sectional imaging suitable for assessing radiodense structures. It utilises a process of tacking many radiographs at differenat rotations around the head, and then computor algorithms to generate a 3D reproduction of a persons tissues.
What are the benefits of CBCT over conventional radiography?
No superimposition
Ability to view subject from any angle
No magnification/distoration
Volumetric reconstruction
What are the drawbacks of CBCT over conventional radiography?
Increased radiation dose to the patient
Lower spatial resolution (less sharp)
Susceptible to artefacts
More expensive equipment and costs
More complicated to manipulate and interperate
Requires additional training
What are the benefits of CBCT over conventional CT?
Lower dose
Higher resolution
Cheaper
Smaller footpring
How should a patient be positioned when taking a CBCT?
Usually standing or sitting
Frankfort plane level with ground
Midsagital plane verticle with machine
What are the benefits of viewing a 3D volume reconstruction for clinicans?
May help identify size/shape of disease
Can be informative teaching aid for patient
Can aid in planning surgical procedures
Endo/ortho purposes
Assessing cystic jaw lesions
What are the limitations of viewing a 3D volume reconstruction for clinicans?
It can create misleading images
It is poor at showing thin areas of bone
What are streak artefacts on a CBCT, and what issues can they causes?
Streaks typically caused by high attenuation objects (metal restorations)
Can prevent caries assessment
Can prevent endodontic assessment of canals
What are the aproximate effective doses for the different types of maxillofacial imaging?
CBCT: 13-82 µS
CT: 474-1160 µSv
Panoramic: 3-24 µSv
Intraoral: 4 µSv
What are the contra-indications for CBCT?
If plain radiograpghs are sufficient
If there is pathology requiring soft tissue visualisation
If there is a high risk of debilitating artefacts
Patient factors (neck-shoulder ratio, Parkinson’s disease)
What additional training is required for use of CBCT in practice?
“Level 1”: for all IRMER duty holders
“Level 2”: for those justifying, performing or interpreting CBCT
Recommended refresher training every 5 years
