OMFPR 2 - Principles of Tomography and Panoramic Imaging (Dr. Ramesh)

Panoramic

_____________ radiography is based on body-section radiography and it blurs out the shadows of superimposed structures

- Broad coverage of facial bones and structures

- Low patient dose

- Simple and convenient

- Can be used on patients with trismus (inability to open mouth)

- Minimal time

What are the five advantages of a panoramic x-rays?

- Critical positioning

- Inherent magnification

- Poor resolution (compared to intraoral radiographs)

- Incorrect interpretation of ghost image

What are the four disadvantages of panoramic x-rays?

All are indications!

Which of the following are an indication for panoramic x-ray?

A) Evaluation of trauma

B) Evaluation of third molars

C) Extensive disease

D) Suspected large lesions

E) Mixed dentition

F) Developmental abnormalities

horizontal

Panoramic radiographs are obtained by rotating a narrow beam of radiation in the __________ plane

narrow

Panoramic radiographs are obtained by rotating a __________ beam of radiation in the horizontal plane

Opposite direction

What direction is the film rotated in while the object (jaw) is stationary?

tomography

Define the following:

Body section radiography

body section radiography

Define the following:

- Technique that blurs out shadows of superimposed structures

- Object of interest less blurred

- Doesn't improve sharpness

focal trough (image layer)

when taking a tomographic image the part of the body that you want to appear the most clearly should be positioned within the _________

focal trough (image layer)

Define the following:

A three-dimensional curved zone or image layer in which structures are reasonably well defined

false (often inaccurate)

t/f: Measurement on a panoramic is often very accurate

true

t/f: Magnification of radiographic structures varies with error in patient positioning

midline

_______ objects may project as single or double images

3

how many centers of rotation are used to take a pano?

double image formation

What has the following characteristics:

- Objects are imaged (intercepted) twice by beam

- One image is mirror image of the other

midline objects

double image formation often occurs with what type of objects?

real image

What type of image is formed when the object is located between the rotation center and film?

ghost image

What type of image is formed when the object is located between the x-ray source and the rotational center?

film

A real image is formed when the object is located between the rotation center and the _____________

x-ray source

A ghost image is formed when the object is located between the rotational center and the _____________

real and double image

the shaded regions will produce what type of images?

ghost image/shadows

the shaded regions will produce what type of images?

3

the shaded region within the blue diamond will produce a total of __ images

2 real

1 ghost

the shaded region within the blue diamond will produce a total of 3 images. What types of images are they?

real image

the following patient has a surgical plate. What type of image is the purple arrow pointing to?

ghost shadows

______________ arise from structures located on the posterior aspect of the head of opposite side

true

t/f: ghost shadows have same general shape and appear on the opposite side

higher

ghost shadows are positioned __________ than real structures

more

ghost shadows are __________ blurred than real structures

more, highly

vertical component of ghost shadows are __________ blurry and __________ magnified

- Antero-posteriorly (too far back or front)

- Supero-inferiorly (chin up or down)

- Mid-sagittal plane (face turned towards right or left)

- Tongue positioning

- Spinal Column positioning

What are five common types of errors with panoramic radiographs?

None - ideal

ID the positional error from the radiograph:

right rotation (pts right side is larger)

(And too far back)

ID the positional error from the radiograph:

left rotation (pts left side is wider)

ID the positional error from the radiograph:

too far front (narrow/elongated incisors)

(And improper tongue positioning)

ID the positional error from the radiograph:

too far forward

when you're looking on a radiograph and the mandibular anteriors look narrow and tall, the pt is ...

too far back

when you're looking on a radiograph and the mandibular anteriors look wider and short, the pt is...

too far back (short/wider incisors)

(and right rotation)

ID the positional error from the radiograph:

chin down

ID the positional error from the radiograph:

chin up

ID the positional error from the radiograph:

none - ideal

ID the positional error from the radiograph:

Improper tongue placement

ID the positional error from the radiograph:

Improper tongue placement

(and too far front?)

ID the positional error from the radiograph:

minification

if a patient is positioned where the incisors are anterior to the center of the focal trough, the image of the incisors will experience ________

magnification

if a patient is positioned where the incisors are posterior to the center of the focal trough, the image of the incisors will experience ________

downward

in order to prevent the cervical vertebrae from appearing on a pano, you can make sure that the patient's chin is tilted slightly _____

ghost image

the blue arrow is pointing to what type of image of the cervical vertebrae?

floor of max. sinus

ID the hard tissue anatomy indicated by the arrow pointing from the red box:

infra orbital canal and foramen

ID the hard tissue anatomy indicated by the arrow pointing from the orange box:

hard palate/floor of nasal fossa

ID the hard tissue anatomy indicated by the arrow pointing from the yellow box:

nasal fossa

ID the hard tissue anatomy indicated by the arrow pointing from the green box:

ant. wall of max. sinus

ID the hard tissue anatomy indicated by the arrow pointing from the light blue box:

coronoid process

ID the hard tissue anatomy indicated by the arrow pointing from the dark blue box:

infra orbital rim

ID the hard tissue anatomy indicated by the arrow pointing from the hot pink box:

pterygomaxillary fissure

ID the hard tissue anatomy indicated by the arrow pointing from the pink/salmon box:

external auditory meatus/ear canal

ID the hard tissue anatomy indicated by the arrow pointing from the brown box:

articular eminence

ID the hard tissue anatomy indicated by the arrow pointing from the white box:

mandibular condyle

ID the hard tissue anatomy indicated by the arrow pointing from the black box:

zygomatic bone

ID the hard tissue anatomy indicated by the arrow pointing from the gray box:

mandibular fossa

ID the hard tissue anatomy indicated by the arrow pointing from the red box:

lateral pterygoid plate

ID the hard tissue anatomy indicated by the arrow pointing from the orange box:

zygomatic process of maxilla

ID the hard tissue anatomy indicated by the arrow pointing from the yellow box:

cervical spine

ID the hard tissue anatomy indicated by the arrow pointing from the green box:

external oblique ridge

ID the hard tissue anatomy indicated by the arrow pointing from the light blue box:

inferior boarder of the mandible

ID the hard tissue anatomy indicated by the arrow pointing from the hot pink box:

mental foramen

ID the hard tissue anatomy indicated by the arrow pointing from the pink/salmon box:

inferior alveolar canal

ID the hard tissue anatomy indicated by the arrow pointing from the black box:

hyoid bone

ID the hard tissue anatomy indicated by the arrow pointing from the white box:

posterior pharyngeal wall

ID the soft tissue anatomy indicated by the arrow pointing from the red box:

soft palate

ID the soft tissue anatomy indicated by the arrow pointing from the orange box:

dorsal surface of tongue

ID the soft tissue anatomy indicated by the arrow pointing from the yellow box:

middle nasal meatus

ID the soft tissue anatomy indicated by the arrow pointing from the green box:

inferior nasal meatus

ID the soft tissue anatomy indicated by the arrow pointing from the light blue box:

inferior nasal concha (turbinate)

ID the soft tissue anatomy indicated by the arrow pointing from the hot pink box:

upper lip

ID the soft tissue anatomy indicated by the arrow pointing from the brown box:

lower lip

ID the soft tissue anatomy indicated by the arrow pointing from the white box:

ghost image of opposite mandible

ID the soft tissue anatomy indicated by the arrow pointing from the grey box:

ala of nose

ID the soft tissue anatomy indicated by the arrow pointing from the red box:

nasal septum

ID the soft tissue anatomy indicated by the arrow pointing from the orange box:

columna (the septum separating the nostrils)

ID the soft tissue anatomy indicated by the arrow pointing from the yellow box:

tragus

ID the soft tissue anatomy indicated by the arrow pointing from the green box:

ear lobe

ID the soft tissue anatomy indicated by the arrow pointing from the light blue box:

- Hard palate

- Epiglottis

-Hyoid bone

- Cervical vertabrae

What midline objects have the ability to project as single/double images? (4)

More (ex: hands on a desk with light above)

The farther the sensor is from anatomy, the ____________ magnification

Buccinator (attaches to the external oblique ridge of the mandible)

What muscle attaches here?