Panoramic Imaging Principles Flashcards
What are the indications for panoramic radiography? (7)
(Evaluation of)
1. overall dentition
2. interosseous pathology (cysts, tumors, etc.)
3. TMJ
4. position of 3rd molars
5. dental development & eruption
6. denomaxillofacial trauma
7. developmental disturbances or syndromes
List the advantages of panoramic radiography: (6)
- Relatively low radiation dose (compared to FMX)
- Broad coverage of facial bones and teeth
- Easier technique
- Can be used in patients with truisms or in patients who cannot tolerate intraoral radiographs (more comfortable & faster)
- Quick and convenient radiograph technique
- Useful visual aid in patient education
List the disadvantages of panoramic radiography: (6)
- Lower resolution areas (not able to detect small carious lesions or early periodontal disease)
- Overlap in premolar area
- Magnification across image is unequal making linear measurements unreliable
- Image superimposition of real, double, and ghost images
- Requires accurate patient positioning (technique sensitive)
- Difficult to image both jaws when patient has severe maxillomandibular discrepancy (class III malocclusion specifically, patient cannot move mandible back to be in line with the maxilla on the bite block)
Because panoramic radiographs have low resolution areas, this does not allow for:
detections of small carious lesions or early periodontal disease
Where do we see overlap in panoramic radiographs?
premolar area
Describe the magnification of panoramic images:
magnification is unequal across the image so making linear measurements is unreliable
Describe when a panoramic may not be indicated due to patient occlusion:
Class III malocclusion (patient cannot move mandible back to be in line with maxillary on bite block)
(would need to do a separate pano of maxilla and mandible)
Label the parts of the panoramic machine:
Blue: Light/Laser localizer (sagittal plane-center)
Orange: Light/Laser localizer (horizontal planevfrankfort)
Yellow: Bite block and handles for patient
Red: X-ray source and tube inside of it
Green: Head supports/guides
Purple: Receptor/sensor of pano machine
What type of panoramic machine does UMKC use?
Orthophos XG Sirona
Label the following parts of the panoramic machine:
B: Light/laser localizer- horizontal plane- frankfurt
C: Light/laser localizer- sagittal plane- center
F: Head supports/guides
I: Receptor/sensor
J: X-ray source & tube inside of it
K: Bite block
M: Bite block handles
When the x-ray source is on the right, the ____ side is being image
left
When x-ray source is on the left side, the ___ side is being imaged
right
Describe the imaging technique of a panoramic machine:
continuous movement imaging
Discuss the collimator location on a panoramic machine:
there is a collimator at both the exit of the source and the entrance of the receptor
In a panoramic machine, there are multiple ____ that are constantly moving:
continuous centers of rotation
Where does the x-ray source start in a panoramic radiograph? Where does it end?
starts on the right and ends on the left
Where does the x-ray source never go in a panoramic radiograph?
NEVER goes in front of the patient
When the source is in the back of the patient, where is the receptor?
In the front of the patient
Where does the head of the patient located at the start of the panoramic radiograph?
between receptor and source
The first image that is created is the patients ____ because the x-ray source starts on the ____
left; right
What is closer to the receptor will be:
imaged
In this image, the x-ray source is on the ____ and the receptor is on the ____.
At what point in time does this occur?
What is being imaged?
right; left
beginning of panoramic
imaging left
In this image, the x-ray source is:
At what point in time does this occur?
Where is the receptor located?
behind the patient
mid-panoramic radiographic
receptor in front
In this image, the x-ray source is:
At what point in time does this occur?
Where is the receptor located?
What is being imaged?
on left side of patient
end of panoramic radiograph
receptor on the right
right side
Instead of ____ receptors, we now use ____ receptors
PSP/Film; CCD
What differs between the CCD receptors we currently use, versus the PSP/Film receptors previously used?
CCD: sensors will be sent to computer and then repeated, exposed on same spot of receptor
PSP/Film: continuously exposed different areas on one receptor
What type of receptor is being described?
Exposure of the same area over and over again and do not need a “new” portion of the receptor
CCD receptor
What type of receptor is being described?
Receptors continuously expose different areas on one receptor
PSP/Film
Area of focus:
focal trough
Describe the focal trough:
an area of focus; a 3D curbed zone in which structures are reasonably and well defined.
Where is the focal trough narrower?
anterior
Is where both dental arches must be positioned to achieve the sharpest images:
Focal trough
Structures positioned in the ___ will result in the clearest images:
center of focal trough
What may occur if objects are placed further from the focal through?
progressively less clear:
- blurred
- magnified
- reduced in size
- distored
How can you ensure sharpness in a panoramic radiograph?
By having both mandibular and maxillary anteriors placed in bite block groove
What does having both mandibular and maxillary anteriors placed in bite block groove ensure in panoramic radiograph?
Ensures sharpness of image
Beams are angulated approximately 4 degrees to avoid projection of:
thick occipital bone
To avoid the occipital bone, beams are angulated approximately:
4 degrees
_____ between the objects in a panoramic radiograph may not be accurate
spacial relationships
Give an example of a spacial relationship that may not be accurate and therefore can be misrepresented on panoramic radiographs
distance between root apex and mandibular canal
Objects closer to the receptor will appear:
narrowed and projected lower on the image
Objects closer to the source will appear:
widened and projected higher up on the image
Objects closer to the ____ will appear narrowed and projected lower on the image
Objects closer to the ____ will appear widened and higher up on the image
receptor; source
Buccal objects will be projected:
lower
Lingual objects will be projected:
higher
_____ objects will be projected lower, while ____ objects will be projected higher
buccal; lingual
Horizontal magnification is determined by:
the position of the object within the focal trough
_____ magnification is determined by the position of the object within the focal trough
horizontal
Magnitude of distortion depends on:
distance of the object from the center of the focal trough
Lingual to the focal trough = closer to the ____ = appears ____
source; wider
_____ to the focal trough = closer to the source = objects appear wider
lingual
Why do objects lingual to the focal trough/closer to the source appear wider?
the beam passes more slowly through it than the speed at which the receptor moved
Buccal to the focal trough = closer to the ____ = appears ____
receptor; narrower
_____ to the focal trough = closer to the receptor = objects appear narrower
buccal
Why do objects buccal to the focal trough/ closer to the receptor appear narrower?
the beam passes at a rate faster than the receptor movement
The green dot would appear ____ while the red dot would appear ____.
Explain
narrower; wider
Green dot is buccal to the focal trough (closer to receptor) and the red dot is lingual to the focal trough (closer to the source)
Image distortions are only in:
the horizontal plane
The image distortions are only in the horizontal plane but varies between:
anterior and posterior regions of the mandible
_____ region = horizontal magnification increases as object moves away from center of focal trough
anterior
What type of horizontal distortions are more severe?
anterior region
____ region = less degree of magnification
posterior region
What type of horizontal distortions are less severe?
posterior region
The magnitude of horizontal distortion varies between:
anterior & posterior regions of the jaw
In the anterior region horizontal magnification increases markedly as the:
object moves AWAY from center of the focal trough
There is less degree of magnification in the:
posterior region
Two identical objects located in the anterior and posterior region may have:
different horizontal magnifications
Horiztonal measurements made on the panoramic radiographs are:
unreliable
Every anatomical structure positioned between the center of rotation & receptor results in:
real images
Where do real images occur?
every anatomical structure between the center of rotation & receptor
This image is describing:
real images
What is depicted by the arrow & dot in this image?
rotation center
Created by objects located between the x-ray source and center of rotation:
ghost images
Describe how ghost images appear:
- on the opposite side
- at a higher level
- blurred and magnified
Anatomical structures that cast a ghost image include: (7)
- inferior border of mandible
- angle of mandible
- ramus of mandible
- hyoid bone
- cervical spine
- jewelry
- palate
Ghost images are created by objects located:
between the x-ray source and center of rotation
- inferior border of mandible
- angle of mandible
- ramus of mandible
- hyoid bone
- cervical spine
- jewelry
- palate
These all have the potential to result in:
ghost images
What does the orange circle represent?
object that would create a ghost image
What does the orange circle represent?
object that would create a real image
List the characteristics of ghost shadows: (4)
- appears on the opposite side
- positioned higher than real structure
- more blurred than real structure
- vertical component is highly magnified
- appears on the opposite side
- positioned higher than real structure
- more blurred than real structure
- vertical component is highly magnified
These are all characteristics of:
ghost shadows
What type of image would this earring create?
ghost image
What can be seen in the panoramic image?
ghost image of inferior border of the mandible and hard palate
What can be seen in this panoramic image?
ghost image of inferior border of the mandible
What can be seen in this panoramic image?
ghost image of nose ring
What can be seen in this panoramic image?
ghost image of necklace
What can be seen in this panoramic image?
ghost image of cervical spine
Objects that lie posterior to the center of rotation and are intercepted twice by the x-ray beam result in:
double images
Double images occur due:
objects that lie posterior to the center of rotation and are intercepted twice by the x-ray beam
What structures may result in double images? (3)
- hyoid bone
- epiglottis
- cervical spine
The hyoid bone, epiglottis, and cervical spine all result in double images, all of which:
cast images on both the right and left side of the image
All double images are:
real images
What is depicted by the orange structure in this image?
object causing double image
What can be seen in this panoramic image?
double image of the hyoid bone
What can be seen in this panoramic image?
double image of the cervical spine
What can be seen in this panoramic image?
double image of the epiglottis
List the steps of positioning for a panoramic x-ray: (9)
- remove jewelry, glasses, & dentures
- place lead apron
- bite in bite block groove
- stand patient upright
- align the center laser line
- align the Frankfurt horizontal plane
- close side guides
- have the patient close their lips, swallow & keep tongue on palate, & hold still
- expose the radiograph
Which image shows the correct body position?
top image
