CBCT Flashcards
what does CBCT stand for
cone beam computed tomography
what type of radiation does CBCT involve
ionising radiation
how does a CBCT machine work
conical/pyramidal x-ray beam
square digital receptor rotate around the head
no more than 1 full rotation
how is the patient positioned for CBCT
machine specific
usually standing or sitting
frankfort plane parallel to floor
mid sagittal plane in the middle
what are the four benefits of CBCT over plain radiography
no superimposition
ability to view subject from any angle
no magnification/ distortion
allows for 3D reconstruction
what are four disadvantages of CBCT over plain radiography
increased radiation dose to patient
lower spatial resolution (not as sharp)
susceptible to artefacts
equipment more expensive
what are two benefits of CBCT vs Conventional CT
lower radiation dose
potential for sharper images
what are the benefits of conventional CT over CBCT
able to differentiate soft tissues better
larger field of view
name four main uses of CBCT in dentistry
relationship between impacted mandibular 8 and IAN canal
measuring alveolar bone dimensions in implant planning
visualising complex root canal morphology to aid endodontic treatment
assessing large cystic jaw lesions
what are the common orthogonal planes
axial
sagittal
coronal
what is the axial plane
looking up through base of skull
what is the sagittal plane
as if skull has been halved at sagittal suture
what is the coronal plane
as if skull has been cut at coronal suture (front view of the face)
what are the three examples of imaging factors/ variables
field of view
voxel size
acquisition time
how are imaging factors/ variables worked out
differs from patient to patient
takes into account ALARP principle
what is the field of view
size of captured volume of data
what is voxel size
the image resolution
voxels = 3D pixels
what does an increase in field of view cause
increase in radiation dose and increase in number of tissue irradiated and increase scatter
what does a decrease voxel cause
increases radiation dose and increased scan time
what are the range of options for voxel size
0.4 mm cubed to 0.085 mm cubed
rate these x-rays by highest dose to lowest :
panoramic, CT, intraoral and CBCT
CT
CBCT
panoramic
intraoral
what are the two main types of artefact
movement artefact
streak artefact
name three contra-indications to CBCT
if plain radiographs are sufficient
high risk of debilitating artefacts
if there is pathology requiring soft tissue visualisation
