Panoramic Radiography
Content
PANORAMIC RADIOGRAPHY
DR. LUBNA F. ALFALEH
Panoramic means “Wide View”
.
Panoramic radiography:
An Extraoral technique which produces a radiograph with wide view of the maxilla and mandible.
it's also known “pantomography” “Rotational panoramic radiography”
Both film and Tube head rotate around the patient
Purpose and use:
To To To
evaluate impacted teeth
evaluate eruption patterns, growth, and Development.
Detect Diseases , lesions, and conditions of the jaws
Examine the extent of Large lesions
To
To
Evaluate Trauma.
Panoramic film are not as Defined or sharp as the images seen on intraoral films, consequently
a panoramic film should not be used to evaluate and diagnose caries, periodontal disease , or periapical lesions.
Normal anatomic landmarks
In Panoramic radiography the film and xrays Tube head move around the patient. The X-ray tube Rotates around the patient‟s head in one direction, while the film rotates in the opposite Direction and patient ( sit or stand ) in stationary position.
The movement of the film and the tube head produces an image through the process known as tomography, the term tomo means section The change in rotation of the tube head allow producing the image layer that confirms elliptical shape of the dental arches.
Different machines
Focal trough
The focal trough (image layer) is Defined as an
invisible area 3 dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
Focal trough
The shape of the Focal trough varies depending on the equipment manufacturer
The structures (teeth and jaws) located within the focal trough appear reasonably well defined in the panoramic radiograph
Focal trough
Structures positioned inside or out side the Focal trough appear blurred or not visible on the panoramic film
In most x-ray machines, the Focal trough is narrow in the anterior region and wide in the posterior region.
Equipment:
1. 2. 3. 4.
X-ray unit. Intensifying screens Screen film Cassette
1. Panoramic X ray Unit
X-ray tube head Head positioner Exposure controls
X ray tube head
Consists of a tube head which is similar to an intraoral x-ray tube head. The collimator used in the panoramic x-ray machine is a lead plate with an opening in the shape of a narrow vertical slit The Tube head always rotates behind the patient‟s head as the film rotates in the front of the patient.
X ray tube head
Head positioner: consists of chin rest, notched Bite-block, forehead rest and lateral head supports Exposure factors are determined by the manufacturer who suggests the (Kvp and Milliamperage). The Kvp and milliamperage settings are adjustable and can be varied to accommodate patients of different sizes The Exposure time is fixed and can‟t be changed
2.Intensifying screens , cassette
Cassette is the device that holds the Extra oral film and the intensifying screens, and it‟s either rigid or Flexible, curved or straight Depending on the used panoramic x-ray unit.
The Screen film is placed between 2 intensifying screens in a cassette holder. Each intensifying screen contains a phosphor layer that fluoresces when activated by x-radiation which has penetrated the cassette.
2.Intensifying screens , cassette
This Exposure methods differs from conventional intraoral radiographs in which x-rays directly exposes the film. Therefore the amount of radiation needed to produce a high quality film is less when using intensifying screens
The green light intensifying screens require less x-rays exposure then the blue one so it‟s faster, that‟s why it‟s recommended.
2.Intensifying screens , cassette
All cassette should be light tight to protect the film from exposure, one intensifying screen is placed on each side of the film
Before exposure a metal letter R can be attached to the front of the cassette to indicate Right from left side of the patient, around with special labeling of patient name., dentist name and the date.
3.Film
Screen film used in panoramic radiography is sensitive to light emitted from intensifying screens
Some Screen film are sensitive to green light others for blue . The film is available in 2 sizes 5x12 inch6x12 inch.
Step by step preparations
Equipment preparation Patient preparation Patient positioning
A. Equipment preparation: 1.Load the panoramic cassette in the dark room under safelight conditions, one extraoral film and 2 intensifying screens must be placed in the cassette, and the cassette must be securely closed. 2.set the Exposure factors according to the manufacturer‟s recommendations e.g. obese patient or patient with large bone>> use the next highest Kvp or mA 3. adjust the machine to the height of the patient, the cassette is loaded in the cassette carrier in the panoramic unit.
B. Patient preparation: 1.Explain the radiographic procedures to be performed. 2.place lead apron, without thyroid collar not to block the the x-ray beam and also double sided lead apron is recommended ( one that protect the patient from the front and the back.
3.remove all objects from the head and neck area. earrings , necklaces, napkin chain eyeglasses. And complete and partial dentures
C .Patient positioning: 1.instruct the patient to Stand or sit ( as tall as possible) with straight back , the vertebral column must be straight to prevent white shadow to appear over the middle of the radiograph. 2. patient must bite a plastic bite block, the front teeth should be placed in end to end position in the notch found on the bite block, this groove will align the teeth and the jaw in the focal trough area .
3. position the midsagittal plane perpendicular
to the floor, and the head should not be tilted 4.position the Frankfort plane (an imaginary plane that passes through the top of the ear canal and the bottom of the eye socket) parallel with floor so that occluasl plane is in correct angle. 5. Instruct the patient to swallow and feel the tongue rise up the roof of the mouth and keep it in that position and close lips around the bite block. 6. patient should remain stand still.
COMMON ERRORS
A. Patient preparation errors B. patient positioning errors.
COMMON ERRORS
A. Patient preparation errors 1.Ghost images: Radiopaque artifact that appear only if the objects Ex (eye glass, orthodontic retainer.. ) are not removed. 2.Lead apron artifact: only if the dental radiographer used lead apron with thyroid collar.
Ghost image
Lead apron artifact
B. Patient positioning errors
1.positioning of lips and tongue : If patient lips are not closed on Bite blocks during the Exposure, Dark radiolucent shadow results that obscure the anterior teeth. If tongue is not in contact with palate , dark radiolucent shadow will Obscure the apices of maxillary teeth.
2.Positinong of Frankfort plane Upward :
If patient „s chin is too high or tipped up, Frankfort plane is angled Upward the following will result: The hard palate and floor of nasal cavity appear superimposed over the roots of maxillary teeth. there is a loss of detail in the maxillary incisors region The maxillary incisors appear blurred and magnified “A reverse smile line “ will appear on the radiograph
3.Positinong of Frankfort plane Downward :
If the patient „s chin is too low, the Frankfort plane is angled down ward it will result in: the mandibular incisors appear blurred There is a loss if detail in the anterior apical region The mandibular condyles may not be visible A “curved Upward smile line” will appear.
4.Postinong of teeth Anterior to Focal trough (not in the groove in the Bite block) The teeth will appear blurred if too far anterior to the focal trough it will appear “skinny” and out of focus.
Teeth Anterior to the Focal trough
5. Positioning of teeth posterior to Focal trough: The teeth will appear blurred If too far the anterior teeth will appear “Fat”
Teeth posterior to the focal trough
Teeth posterior to the focal trough
6. Positioning of Midsagittal plane: if the patient head is not centered the ramus and the posterior teeth appear unequally magnified on the panoramic radiograph The side farthest from the film appears magnified and the closer appear smaller.
7.Postioning of spine: If patient is not sitting or standing with stright back ,cervical spine appears as radiopacity in the center of the film
END OF LECTURE
ADVANTAGES AND DISADVANTAGES
Advantages:
1.
2. 3. 4.
Field size: coverage of the Entire Maxilla and mandible , so more anatomical structures and lesion can be viewed Simplicity. Patient cooperation (no discomfort) especially children. Minimal exposure: minimal radiation Exposure for the patient.
Disadvantages:
Image quality: not as sharp as intraoral radiographs (because of the intensifying screens). That‟s why You can‟t evaluate Details like ( dental caries , periodontal disease or periapical lesions. 2. Focal trough limitations: any object outside focal trough can‟t be seen. 3. Distortion: A certain amount of magnification, distortion , overlapping is present even if proper technique is used 4. Equipment cost: high compared to intraoral radiography Unit.
1.
DR. LUBNA F. ALFALEH
Panoramic means “Wide View”
.
Panoramic radiography:
An Extraoral technique which produces a radiograph with wide view of the maxilla and mandible.
it's also known “pantomography” “Rotational panoramic radiography”
Both film and Tube head rotate around the patient
Purpose and use:
To To To
evaluate impacted teeth
evaluate eruption patterns, growth, and Development.
Detect Diseases , lesions, and conditions of the jaws
Examine the extent of Large lesions
To
To
Evaluate Trauma.
Panoramic film are not as Defined or sharp as the images seen on intraoral films, consequently
a panoramic film should not be used to evaluate and diagnose caries, periodontal disease , or periapical lesions.
Normal anatomic landmarks
In Panoramic radiography the film and xrays Tube head move around the patient. The X-ray tube Rotates around the patient‟s head in one direction, while the film rotates in the opposite Direction and patient ( sit or stand ) in stationary position.
The movement of the film and the tube head produces an image through the process known as tomography, the term tomo means section The change in rotation of the tube head allow producing the image layer that confirms elliptical shape of the dental arches.
Different machines
Focal trough
The focal trough (image layer) is Defined as an
invisible area 3 dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
Focal trough
The shape of the Focal trough varies depending on the equipment manufacturer
The structures (teeth and jaws) located within the focal trough appear reasonably well defined in the panoramic radiograph
Focal trough
Structures positioned inside or out side the Focal trough appear blurred or not visible on the panoramic film
In most x-ray machines, the Focal trough is narrow in the anterior region and wide in the posterior region.
Equipment:
1. 2. 3. 4.
X-ray unit. Intensifying screens Screen film Cassette
1. Panoramic X ray Unit
X-ray tube head Head positioner Exposure controls
X ray tube head
Consists of a tube head which is similar to an intraoral x-ray tube head. The collimator used in the panoramic x-ray machine is a lead plate with an opening in the shape of a narrow vertical slit The Tube head always rotates behind the patient‟s head as the film rotates in the front of the patient.
X ray tube head
Head positioner: consists of chin rest, notched Bite-block, forehead rest and lateral head supports Exposure factors are determined by the manufacturer who suggests the (Kvp and Milliamperage). The Kvp and milliamperage settings are adjustable and can be varied to accommodate patients of different sizes The Exposure time is fixed and can‟t be changed
2.Intensifying screens , cassette
Cassette is the device that holds the Extra oral film and the intensifying screens, and it‟s either rigid or Flexible, curved or straight Depending on the used panoramic x-ray unit.
The Screen film is placed between 2 intensifying screens in a cassette holder. Each intensifying screen contains a phosphor layer that fluoresces when activated by x-radiation which has penetrated the cassette.
2.Intensifying screens , cassette
This Exposure methods differs from conventional intraoral radiographs in which x-rays directly exposes the film. Therefore the amount of radiation needed to produce a high quality film is less when using intensifying screens
The green light intensifying screens require less x-rays exposure then the blue one so it‟s faster, that‟s why it‟s recommended.
2.Intensifying screens , cassette
All cassette should be light tight to protect the film from exposure, one intensifying screen is placed on each side of the film
Before exposure a metal letter R can be attached to the front of the cassette to indicate Right from left side of the patient, around with special labeling of patient name., dentist name and the date.
3.Film
Screen film used in panoramic radiography is sensitive to light emitted from intensifying screens
Some Screen film are sensitive to green light others for blue . The film is available in 2 sizes 5x12 inch6x12 inch.
Step by step preparations
Equipment preparation Patient preparation Patient positioning
A. Equipment preparation: 1.Load the panoramic cassette in the dark room under safelight conditions, one extraoral film and 2 intensifying screens must be placed in the cassette, and the cassette must be securely closed. 2.set the Exposure factors according to the manufacturer‟s recommendations e.g. obese patient or patient with large bone>> use the next highest Kvp or mA 3. adjust the machine to the height of the patient, the cassette is loaded in the cassette carrier in the panoramic unit.
B. Patient preparation: 1.Explain the radiographic procedures to be performed. 2.place lead apron, without thyroid collar not to block the the x-ray beam and also double sided lead apron is recommended ( one that protect the patient from the front and the back.
3.remove all objects from the head and neck area. earrings , necklaces, napkin chain eyeglasses. And complete and partial dentures
C .Patient positioning: 1.instruct the patient to Stand or sit ( as tall as possible) with straight back , the vertebral column must be straight to prevent white shadow to appear over the middle of the radiograph. 2. patient must bite a plastic bite block, the front teeth should be placed in end to end position in the notch found on the bite block, this groove will align the teeth and the jaw in the focal trough area .
3. position the midsagittal plane perpendicular
to the floor, and the head should not be tilted 4.position the Frankfort plane (an imaginary plane that passes through the top of the ear canal and the bottom of the eye socket) parallel with floor so that occluasl plane is in correct angle. 5. Instruct the patient to swallow and feel the tongue rise up the roof of the mouth and keep it in that position and close lips around the bite block. 6. patient should remain stand still.
COMMON ERRORS
A. Patient preparation errors B. patient positioning errors.
COMMON ERRORS
A. Patient preparation errors 1.Ghost images: Radiopaque artifact that appear only if the objects Ex (eye glass, orthodontic retainer.. ) are not removed. 2.Lead apron artifact: only if the dental radiographer used lead apron with thyroid collar.
Ghost image
Lead apron artifact
B. Patient positioning errors
1.positioning of lips and tongue : If patient lips are not closed on Bite blocks during the Exposure, Dark radiolucent shadow results that obscure the anterior teeth. If tongue is not in contact with palate , dark radiolucent shadow will Obscure the apices of maxillary teeth.
2.Positinong of Frankfort plane Upward :
If patient „s chin is too high or tipped up, Frankfort plane is angled Upward the following will result: The hard palate and floor of nasal cavity appear superimposed over the roots of maxillary teeth. there is a loss of detail in the maxillary incisors region The maxillary incisors appear blurred and magnified “A reverse smile line “ will appear on the radiograph
3.Positinong of Frankfort plane Downward :
If the patient „s chin is too low, the Frankfort plane is angled down ward it will result in: the mandibular incisors appear blurred There is a loss if detail in the anterior apical region The mandibular condyles may not be visible A “curved Upward smile line” will appear.
4.Postinong of teeth Anterior to Focal trough (not in the groove in the Bite block) The teeth will appear blurred if too far anterior to the focal trough it will appear “skinny” and out of focus.
Teeth Anterior to the Focal trough
5. Positioning of teeth posterior to Focal trough: The teeth will appear blurred If too far the anterior teeth will appear “Fat”
Teeth posterior to the focal trough
Teeth posterior to the focal trough
6. Positioning of Midsagittal plane: if the patient head is not centered the ramus and the posterior teeth appear unequally magnified on the panoramic radiograph The side farthest from the film appears magnified and the closer appear smaller.
7.Postioning of spine: If patient is not sitting or standing with stright back ,cervical spine appears as radiopacity in the center of the film
END OF LECTURE
ADVANTAGES AND DISADVANTAGES
Advantages:
1.
2. 3. 4.
Field size: coverage of the Entire Maxilla and mandible , so more anatomical structures and lesion can be viewed Simplicity. Patient cooperation (no discomfort) especially children. Minimal exposure: minimal radiation Exposure for the patient.
Disadvantages:
Image quality: not as sharp as intraoral radiographs (because of the intensifying screens). That‟s why You can‟t evaluate Details like ( dental caries , periodontal disease or periapical lesions. 2. Focal trough limitations: any object outside focal trough can‟t be seen. 3. Distortion: A certain amount of magnification, distortion , overlapping is present even if proper technique is used 4. Equipment cost: high compared to intraoral radiography Unit.
1.
