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. dentomaxillofacial 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 & teeth
- easier technique
- can be used in patients with trismus or in patients who cannot tolerate intraoral radiographs (more comfortable & faster)
- quick & convenient radiographic technique
- useful visual aid in patient education
List the disadvantages of panoramic radiography: (6)
- lower resolution areas (not able to detect small carious lesions of early periodontal disease)
- overlap in premolar area
- magnification across image is equal making linear measurements unreliable
- image is superimposition of real, double & 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 maxilla on bite block)
Because panoramic radiographs have lower resolution areas this does not allow for:
detection of small carious lesions or early periodontal disease
Where do we see overlap in panoramic radiographs?
premolar areas
Describe the magnification of panoramic images:
magnification across image is unequal so linear measurements are unreliable
Describe when a panoramic radiograph may not be indicated due to patient occlusion:
Class III malocclusion (patient cannot move mandible back to align with maxilla on bite stick)
(would need to obtain separate panoramic images of maxilla and mandible)
Label the following parts of the panoramic machine:
Blue: light/laser localizer (sagittal plane-center)
Orange: light/laser localizer (horizontal plane- frankfurt)
Yellow: bite block & handles for patient
Red: X-ray source & the tube inside it
Green: Head support/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
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- handles for patient
When the X-ray source is on the right side, the ____ side is being imaged
left
When the X-ray source is on the left side, the ____ 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 are constantly moving
Centers of rotation
Where does the X-ray source start in a panoramic radiograph?
Where does the X-ray source end in a panoramic radiograph?
Starts on the right
Ends on the left
Where does the X-ray source NEVER go in a panoramic radiograph?
NEVER goes in front of patient
When the source is in the back of the patient, where is the receptor?
In the front of the patient
Where is the head of the patient located at the start of the panoramic radiograph?
Between the receptor and the 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 is what 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 during a panoramic radiograph?
What is being imaged?
right; left
Beginning of panoramic radiograph
Imaging left
In this image, the X-ray source is:
At what point in time does this occur during a panoramic radiograph?
Where is the receptor located?
behind the patient
Mid panoramic radiograph
receptor is in front
In this image, the X-ray source is:
At what point in time does this occur during a panoramic radiograph?
Where is the receptor located?
What is being imaged?
left side of patient
End of panoramic radiograph
receptor is on the right side
imaging right
Instead of ______ receptors we now use _____ receptors
PSP/Film; CCD
What differs between the CCD receptors we use now vs. the PSP/Film receptors previously used:
CCD: Sensors will be sent to computer and then repeated, exposed on same spot of receptor
PSP/Film: receptors continuously expose 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 receptor
Area of focus:
Focal trough
Describe the focal trough:
An area of focus; a 3D curved zone in which structures are reasonable and well defined
Where is the focal trough narrower?
Anteriorly
Is where both dental arches must be positioned to achieve the sharpest images:
Focal trough
Structures placed in the ______ will result in the clearest image
center of focal trough
What may occur if objects are placed further from the focal trough?
Progressively less clear:
-blurred
-magnified
-reduced in size
-distorted
How can you ensure sharpness in a panoramic radiograph?
By having both mandibular and maxillary anteriors placed in blot 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 may not be accurate in a panoramic radiograph
spatial relationships
Give an example of a spatial relationship that may not be accurate, and therefore can be misrepresented on panoramic radiographs:
distance between root apex & mandibular canal
Objects closer to the receptor will appear:
Narrowed & projected lower on the image
Objects closer to the source will appear:
widened & projected higher up on the image
Objects closer to the ____ will appear narrowed & projected lower on the image
Objects closer to the ____ will appear widened & higher up
receptor; source
Buccal objects will be projected:
lower
Lingual objects will be projected:
higher
____ objects will be projected lower, while ____ objected 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 _____
The red dot would appear ____
Explain
narrower; wider
Green dot is buccal to the focal tough (closer to the receptor)
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 & posterior regions of the mandible
____ region = horizontal magnification increases as object moves away from center of focal trough
anterior region
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 the center of the focal trough
There is a less degree of magnification in the:
posterior region
Two identical objects located in the anterior & posterior regions may have:
different horizontal magnifications
Horizontal measurements made on panoramic radiographs are:
unreliable
Every anatomical structure positioned between the center of rotation & the receptor results in:
real images
Where do real images occur?
every anatomical structure positioned between the center of rotation & the 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 & the center of rotation:
Ghost images
Describe how ghost images appear{
- on the opposite side
- at a higher level
- blurred & 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 image are created by objects located:
between the X-ray source & 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
These are all characteristics of:
ghost shadows
What type of image would this earring create?
ghost image
What can be seen in this 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 that are intercepted twice by the X-ray beam result in:
double images
Double images occur due to:
objects that lie posterior to the center of rotation & are intercepted twice by the X-ray beam
What structures may result in double images? (3)
- hyoid bone
- epiglottis
- cervical spine
They hyoid bone, epiglottis & cervical spine, all result in double images, all of which:
cast images on both the right & 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 biteblock groove
- stand patient upright
- align the center laser line
- align the Frankfurt horizontal plane
- close side guides
- Have Pt close their lips, swallow & keep tongue on palate & hold still
- expose the radiograph
What image shows the correct body position?
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