wk 5: Panoramic Radiography Flashcards
what are the indications for Panoramic Radiographs
Evaluate trauma, Pathology and third molar location
Mixed Dentition
Evaluate developmental anomalies
Advantages of Panoramic Radiographs
large anatomical area covered
relatively low dose
easy to operate
improved patient cooperation’
used with patients with trismus
short time
Disadvantages of Panoramic radiographs
decreased sharpness
proximal surfaces overlap
slight magnification and distortion
overlapping structures
relatively high cost
may not see objects outside focal trough
When are IOPA preferred over OPG
Caries
periodontal involvement
early periodical pathology
endo treatment
shape of collimator in IOPA vs OPG
IOPA= circle
OPG= Rectangle
what is the focal trough
three dimensional curved zone or image layer which structures are reasonably well defined
what are the dimensions of focal trough
- front to back
- side to side
- up and down
what is the vertical angulation of a panoramic Xray
8 degrees
how much vertical magnification occurs in panoramic xrays
10%
what is a single real image
only one image results from a given anatomical structure.
Located between the rotation centre and the film.
Xray beam only passes through it one time
What is a double real image
two images of a single object are sen on the film
produced by structures in the midline
xray beam passes through twice
what is a ghost image
formed by dense objects located between the tube head and the rotation centre
usually external objects like earrings or commonly the mandible
what are the characteristics of a ghost image
opposite side
same shape
less distinct
larger
projected higher on film
what type of Xray protection is indicated for Panoramic X-rays
Lead apron, Thyroid collars are contradicted
what are the 4 principles of panoramic positioning
- incisors in the notch of bitestick
- Frankfort plane parallel to floor
- midsagittal plane centered
- spinal column straight
