Techniques Flashcards
What relationship is key to the quality of an image?
x-ray source
object
receptor
what are the 2 intra oral radiographic techniques?
bisected angle
paralleling
what is the standard intra oral technique?
paralleling
what makes bisected angle easier for patient?
no holder required - patient holds film in their mouth
when is bisected angle commonly used?
endodontic procedures
how does paralleling create a reproducible image?
holder keeps receptor parallel to tooth and x-ray beam
- accurate geometry
- minimises magnification
what are holders made up of?
bite block (receptor)
indicator arm/ rod
aiming ring
what are the colours of holders?
blue - anterior
yellow - posterior
red - bitewings
green - endo
what is the object that the image is taken on?
receptor
what are receptors?
phosphor plates which are processed, erased and reused
what type of radiology uses phosphor plates?
computed
what are the 4 common sizes of receptors for intraoral?
0 1 2 4
position of vertical plane?
parallel to long axis of tooth
distortion of vertical plane results in?
elongated apex of tooth
roots projected off the top of receptor
horizontal plane positioning?
parallel to dental arch
distortion of horizontal plane results in?
overlapping
position of x-ray beam?
right angle to tooth and receptor
what happens if x-ray beam too angled up?
stretch teeth - elongated
what happens if x-ray beam too angled down?
foreshorten teeth - short stubby appearance
horizontal angulation of x-ray beam causes?
overlapping
what is the rectangle attachment at the end of the x-ray tube?
collimator
what does rectangular collimation do?
reduce dose to patient by up to 50%
what positioning is good magnification?
long distance between x-ray source and receptor
short distance between object and receptor
where should the dot on the receptor be placed?
next to the crown of the tooth
bitewing - next to palate
upwards angulation of x-ray beam results in?
elongated teeth
downwards angulation of x-ray beam results in?
foreshortened teeth
what are bitewings used for?
detect caries
monitor caries progression
assess periodontal status
assess existing restorations
what’s the dose difference between vertical and horizontal bitewings?
vertical 4 times radiation
horizontal 2 times radiation
what happens if there are gaps when aligning collimator and guiding ring?
beam will hit receptor at an angle and cause overlap, elongation or foreshorting
what are the 2 types of holders?
rigid plastic
paper tab
when may you use the paper tab holder?
patient cant tolerate plastic
