Cone Beam CT Flashcards
what is CBCT
cross sectional imaging suitable for assessing radiodense structures
how does CBCT work
radiation x-rays catches many 2D images which are reconstructed into cylindrical 3D image
how is the patient positioned for a CBCT
same as OPT with frankfort plane parallel to floor
what are the benefits of CBCT compared to normal radiography
no superimposition
ability to view subject from any angle
no magnification/distortion
allows for volumetric reconstruction
what are the downsides of CBCT compared to normal radiography
increased radiation dose to patient
lower spatial resolution
susceptible to artefacts
equipment more expensive
images complication to manipulate
requires additional training to justify, operate and interpret
what are the benefits of CBCT to CT
lower radiation dose
potential for sharper images
cheaper
smaller footprint
what are the benefits of CT scans to CBCT
able to differentiate soft tissues better
cleaner images
larger field of view possible
what are the common uses of CBCT in dentistry
clarifying relationships between impacted mandibular third molars and inferior alveolar canal
measure alveolar bone dimensions for implants
visualise complex root canal morphology for endo
investigate external root resorption
assess large cystic jaw lesions
what are the uses of 3D volume reconstruction
help picture extent/shape of disease
can be informative teaching aid for patient
what are the drawbacks of 3D volume reconstruction
modified reconstruction of the data and so can create misleading images
what is used for image resolution instead of pixels
voxels
what does decreased voxels size lead to
increased radiation dose and increased scan time
when would you use smaller voxels
when you need fine detail
what are artefacts
visualised structures on scan that were not present in object investigated
what are movement artefacts
when the patient is not still and leads to blurriness or extra contours
