2: Radiology Lecture 3: Pano

Front 1

Panorex early model:

1) 3 components?
2) Pattern of movement?
3) Downfall?

Back 1

1) Film cassette, slit collimator, x-ray tube
2) 2 centers of rotation, portion of circle radius = arch.
3) Chair shifts = period of no exposure, but the film continues to move. Unexposed area of anterior film, double images of anterior teeth and double chin

Front 2

3 principles of panoramic radiography?

Back 2

Scannography, tomography, pantomography

Front 3

What happens during the scanning technique?

Back 3

X-ray and film move across patient, x-ray passes through slit collimation, narrow x-ray beam scans patient and thin strip of anatomy is recorded on film - multiple strips = image.

Front 4

What happens during collimated beam scanning?

Back 4

One vertical area at a time, reduces patient exposure area. Composite of all equals final image

Front 5

What is the concept of tomography?

Back 5

Image results from moving x-ray beam and film in opposite directions. Angle = width

Front 6

How many ways can you image a curved arch? What is orthopantomography?

Back 6

Single circle, double circle, triple circle, continuous path. Orthopantomography = triple circle panotmography.

Front 7

What is the focal trough/layer/plane?

Back 7

3D area - mandibular arch, vertical height (inferior orbital rim, below hyoid), horizontal width

Front 8

Compare the focal trough of the panorex, orthopantomograph, panelipse.

Back 8

Panorex - greater focal trough width for greater patient positioning. Unsharpness in TMJ area.

Orthopantomograph+panelipse narrow in anterior, wide in posterior. Little positioning error, good sharpness. Wider areas in front less focused on anterior teeth.

Front 9

What is the objective of the focal trough?

Back 9

Increase image sharpness. Objects may have varying sharpness depending on position in and near focal trough.

Front 10

4 things on the machine that help align the focal tough?

Back 10

1) Incisal guide
2) Head holder
3) Light alignment - midsagittal, canine/cuspid
4) Chin holder

Front 11

Planmeca:

1) What is it?
2) What are the three alignment methods?

Back 11

1) New gen pano macine
2) Midsagittal, vertical (Frankfort plane), canine (focal trough)

Front 12

Focal trough factor 1: XRAY BEAM

1) Angle?
2) Why do you do this?

Back 12

1) Upwards 5-7 degrees
2) to prevent superimposition of occipital region, hard palate, root apices

Front 13

Focal trough factor 2: PATIENT CHIN TIPPED DOWNWARD

Why do you do this?

Back 13

To get the occipital region and hard palate above the root apices

Front 14

FOCAL TROUGH FACTOR 3:

Where should anteriors be?

Back 14

In the focal tough

Front 15

FOCAL TROUGH FACTOR 4:

What is the proper position?

Back 15

1) Slight downward occlusal incline
2) Incisors in focal trough
3) Lower incisors critical for positioning

Front 16

Result of tipping chin too far down?

Back 16

Exaggerated smile, lower incisors pictured out of focus of trough, condyles are project off top of film

Front 17

Chin tipped too far up?

Back 17

Flat smile, palate projected over root apices, condyles low position

Front 18

Teeth anterior to focal trough?

Back 18

Horizontal dimension change, teeth narrow. Minimal vertical distortion

Front 19

Teeth posterior to focal trough?

Back 19

Horizontal distortion, wide and fat teeth, minimal vertical distortion

Front 20

3 areas of anatomical coverage?

Back 20

R+L, vertical (inferior orbital rim, below hyoid), horizontal (occipital to occipital)