Module 20: Panoramic Radiography

C

1- Which of the following describes a use of a panoramic image? a. diagnosis of caries b. evaluation of periodontal disease c. evaluation of impacted molars d. evaluation of periapical disease

bitewing, periapical impacted eruption diseases extent trauma

1. Describe the purposes and appearance of panoramic film. A panoramic image is often used to supplement ___ and ____ images. The panoramic image is typically used for the following purposes: • To evaluate ___ teeth. • To evaluate ___ patterns, growth, and development. • To detect ___, lesions, and conditions of the jaws. • To examine the ___ of large lesions. • To evaluate ____.

maxilla and mandible extraoral, extraoral individual

1. Describe the purposes and appearance of panoramic film. A panoramic image shows a wide view of the ___ and the ___. Panoramic imaging is an ____ technique that is used to examine the maxilla and the mandible on a single projection. An ___ receptor is positioned outside the mouth during X-ray exposure. In panoramic imaging (also known as rotational panoramic imaging), both the receptor and the tubehead rotate around the patient, producing a series of ____ images. When such images are combined, an overall view of the maxilla and the mandible is created.

defined or sharp, caries, periodontal disease, or periapical lesions intraoral

1. Describe the purposes and appearance of panoramic film. The images on a panoramic projection are not as ____ or ___ as the images seen on intraoral projections. Consequently, a panoramic image should not be used to evaluate and diagnose ___, ___ ___, or ___ ___. The panoramic image should not be used as a substitute for ___ projections.

tomography, tomography

1. Describe the purposes and appearance of panoramic film. The movement of the receptor and the tubehead produces an image through the process known as ____. ___ is an imaging technique that allows the imaging of one layer, or section, of the body while blurring the images of structures in other planes. In panoramic imaging, this image conforms to the shape of the dental arches.

A

10. The collimator is a lead plate with an opening in the shape of a narrow vertical slit. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

B

11. The collimator is a lead plate with a small, round or rectangular opening. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

B

12. The vertical angulation of the tubehead is variable. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A

13. A head positioner is used to position the patient's head. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A or B??

14. A screen film is used. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A

15. A cassette holder with two intensifying screens is used. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A

16. The x ray film must be loaded into a cassette in a darkroom under safelight conditions. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

B

17. A lead apron with a thyroid collar must be placed on the patient. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A or C???

18. All jewelry (earrings and necklaces) must be removed before exposure. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

C

19. The midsagittal plane must be positioned perpendicular to the floor. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

No (but kilovoltage and milliamperage can be changed)

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. Can the exposure time of a panoramic machine be changed?

extraoral, intesnsifying screens,

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. The cassette is a device that is used to hold the ___ film and ___ ___. The cassette may be rigid or flexible, curved or straight, depending on the panoramic x-ray unit: All cassettes must be "light-tight to protect the film from exposure. One intensifying screen is placed on each side of the film and held in place when the cassette is closed. The cassette must be marked to orient the finished image. Before exposure, a metal letter "R" can be attached to the front of the cassette to indicate the patient's right side; the letter "I" is used to identify the patient's left side. Special labeling may also be attached to indicate the patient's name, the dentist's name, and the date. If the cassette is not labeled before exposure, the film must be labeled immediately after processing. A marking pen or adhesive label can be used to label the image.

vertical; narrow, cassette carrier, narrow; upward, behind, front

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. The collimator used in the panoramic x-ray machine is a lead plate with an opening in the shape of a narrow ___ slit. The x-ray beam emerges from the panoramic tubehead through the collimator as a ___ band. The beam passes through the patient and then exposes the receptor through another vertical slit in the ___ ___ (the metal holder that supports the cassette). The ___ x-ray beam that emerges from the collimator minimizes patient exposure to x-radiation. The tubehead of the panoramic unit is fixed in position so that the x-ray beam is directed slightly ___. In addition, the tubehead of the panoramic unit always rotates ___ the patient's head, while the receptor rotates in ____ of the patient.

• x-ray tubehead • Head positioner • exposure controls

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. The main components of the panoramic unit include:

rotation center; • Double-center rotation • Triple-center rotation • Moving-center rotation

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. The pivotal point, or axis, around which the receptor and the x-ray tubehead rotate is termed the ___ ___. One of three basic rotation centers is used in panoramic x-ray machines:

Calcium tungstate, rare earth; less, faster; rare earth

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. Two basic types of intensifying screens are used: calcium tungstate and rare earth. • ______ screens emit blue light, and the ____ screens emit green light. • Rare earth screens require ___ x-ray exposure than do calcium tungstate screens and are considered "____." • Consequently, ____ screens are recommended in panoramic imaging because of less exposure of the patient to radiation.

Screen film, screen film; green, blue, blue, green

2. Describe the radiographic equipment and technique for exposing a panoramic film. Include the purpose and use of an intensifying screen. ___ ____ is used in panoramic imaging; this film is sensitive to the light emitted from intensifying screens. A ___ ___ is placed between two intensifying screens in a cassette holder. When the cassette holder is exposed to x-rays, the screens convert the x-ray energy into light, which, in turn, exposes the screen film. Available in 5X12" or 6X12". Some screen films are sensitive to ___ light (Kodak T-Mat G and Ortho G film), whereas others are sensitive to ___ light (Kodak X-Omat RP and Ektamat G films). ___-sensitive film must be paired with screens that produce blue light, And ___ sensitive film must be paired with screens that produce greenlight.

a

2. The zone in which structures are clearly demonstrated on a panoramic image is termed: a. the focal trough b. the rotation center c. the ghost image d. the midsagittal plane

A

20. The vertebral column must be perfectly straight. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

midsagittal plane

3. Describe and explain what the "focal trough" or image layer is, the midsagittal plane, Frankfort plane an imaginary line that divides the patient's face into right and left sides) perpendicular to the floor. The patient's head must not be tipped or tilted; if the ___ ___ is not positioned perpendicular to the floor, a distorted image results.

arches, defined, blurred; narrower, narrow, wider; teeth, maxilla, mandible

3. Describe and explain what the "focal trough" or image layer is, the midsagittal plane, Frankfort plane. In panoramic imaging, the focal through is a theoretical concept used to determine where the dental ____ must be positioned to obtain the clearest image. The focal trough (also known as the image layer) can be defined as a three-dimensional curved zone in which structures are clearly demonstrated on a panoramic image. The structures located within the focal trough appear reasonably well ____ on the resulting panoramic image. The structures positioned inside or outside of the focal trough appear ____ or indistinct and are not readily visible on the panoramic image. The size and shape of the focal trough vary, depending on the manufacturer of the panoramic x-ray unit. The closer the rotation center is to teeth, the ___ is the focal trough. In most panoramic x-ray machines, the focal trough is ____ in the anterior region and ____ in the posterior region. Each panoramic x-ray unit has a focal trough that is designed to accommodate the average jaw. Each manufacturer provides specific instructions about patient positioning to ensure that the teeth are positioned within the focal trough. The quality of the resulting panoramic image depends on the positioning of the patient's ___ within the focal trough and how closely the patient's ___ and ___ conform to the focal trough designed for the average jaw.

Frankfort plane

3. Describe and explain what the "focal trough" or image layer is, the midsagittal plane, Frankfort plane. an imaginary plane that passes through the top of the ear canal and the bottom of the eye socket) parallel to the floor. When the ___ ___ is parallel to the floor, the occlusal plane is positioned at the correct angle.

c

3. Rare earth intensifying screens are recommended in panoramic imaging because: a. rare earth screens emit a blue light b. rare earth screens provide a more diagnostic image c. rare earth screens require less x-ray exposure for the patient d. the images convert faster in automatic processors

a

4. A thyroid collar is not recommended in panoramic imaging because: a. it blocks the X-ray beam and obscures information b. there is a relatively low dose of radiation to the thyroid gland in panoramic imaging c. it is impossible to sterilize the thyroid collar d. all of the above

Field size Simplicity Patient cooperation Minimal exposure

4. State the advantages & disadvantages of panoramic radiography. Advantages 1. ____. The panoramic image covers the entire maxilla and mandible. More anatomic structures can be viewed on a panoramic image than with a complete mouth radiographic series (CMRS). In addition, lesions and conditions of the jaws that may not be seen on intraoral images can be detected on a panoramic image. 2. ______. Exposure of a panoramic receptor is relatively simple and requires minimal amounts of time and training for the dental radiographer. 3. ____ ____. The exposure of a panoramic image is more acceptable to the patient because no discomfort is involved. For example, children who may not be able to tolerate intraoral projections may find it easier to sit still during the exposure of a panoramic image. 4. ____ ____. A panoramic image involves only minimal radiation exposure of the patient.

Image quality Focal trough Distortion Equipment cost

4. State the advantages & disadvantages of panoramic radiography. Disadvantages 1. ___ ____. The images seen on a panoramic image are not as sharp as intraoral projections because of the intensifying screens. As a result, the panoramic image cannot be used to evaluate dental caries, periodontal disease, or periapical lesions. 2. ___ ____ limitations. Objects of interest that are located outside the focal trough cannot be seen. 3. ____. Certain amounts of magnification, distortion, and overlapping are present on a panoramic image, even when proper technique is used. 4. ___ ____. The cost of a panoramic x-ray unit is relatively high compared with the cost of an intraoral X-ray unit.

One, two; sterilized; carrier

5. Describe & demonstrate the procedures, including patient positioning, involved in exposing and processing a panoramic film & panoramic digital image. Equipment preparation for panoramic imaging 1. If using film, load the panoramic cassette in the darkroom under safelight conditions. ___ extraoral film and ____ intensifying screens must be placed in the cassette, and the cassette must be securely closed. 2. Cover the bite-block with a disposable plastic coverslip. If the bite-block is not covered with an impervious material (e.g., plastic coverslip), it must be ___ between patients. 3. Set the exposure factors (kilovoltage, milliamperage) according to the manufacturer's recommendations. Adjust the machine to accommodate the height of the patient, and align all movable parts properly. The cassette must be loaded in the cassette ____ of the panoramic unit.

thyroid collar

5. Describe & demonstrate the procedures, including patient positioning, involved in exposing and processing a panoramic film & panoramic digital image. Patient preparation for panoramic imaging • Explain to the patient the imaging procedure about to be performed. 2. Place a lead apron, without a ___ ___, on the patient, and secure it. A double-sided lead apron (one that protects the front and back of the patient) is recommended. The lead apron must be placed low around the neck so that it does not block the x-ray beam. A thyroid collar is not recommended for panoramic imaging because it blocks part of the beam and obscures important diagnostic information. 3. Have the patient remove all objects from the head- and-neck area that may interfere with the procedure. The patient must remove eyeglasses, earrings, necklaces, napkin chains, hearing aids, hairpins, and complete or partial dentures. 1. Instruct the patient to sit or stand "as tall as possible" with the back erect. The vertebral column must be perfectly straight. The spinal column is very dense; if the spine is not straight, a white shadow appears over the middle of the image and obscures diagnostic information. 2. Instruct the patient to bite on the plastic bite-block. Maxillary and mandibular anterior teeth must be in an end-to-end position in the groove (notch) on the bite-block. This groove is used to align the teeth to the focal trough. (In an edentulous patient, the radiographer must align the patient's maxillary and mandibular ridges over the notched area on the bite-block. Cotton rolls can be placed on each side of the bite-block to provide stabilization for the patient.) 3. Position the midsagittal plane (an imaginary line that divides the patient's face into right and left sides) perpendicular to the floor). The patient's head must not be tipped or tilted; if the midsagittal plane is not positioned perpendicular to the floor, a distorted image results. 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 to the floor (Figure 22-15). When the Frankfort plane is parallel to the floor, the occlusal plane is positioned at the correct angle. 5. Instruct the patient to place the tongue on the roof of the mouth. You may suggest that the patient "swallow and feel the tongue rise up to the roof of the mouth" and then instruct the patient to keep the tongue in that position during the procedure. Also, instruct the patient to close the lips around the bite-block. 6. After the patient has been positioned, instruct the patient to remain still while the machine is rotating during exposure. 7. Expose the receptor and if using film, proceed with film processing as described in Chapter

b

5. The imaginary line that passes from the bottom of the eye socket through the top of the ear canal is termed: a. the midsagittal plane b. the Frankfort plane c. the vertebral plane d. the orbital plane

CH 22 & 29

6. Review and identify the following common anatomical landmarks that may be possible to view on panoramic radiographs. Palate Orbit and nasal cavity Maxillary sinus Maxillary tuberosity Articular eminence and glenoid fossa Mandibular condyle Coronoid process External oblique ridge/line Angle of mandible Vertebra Mandibular canal Mental foramen

A

6. The receptor and the tubehead rotate around the patient. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

blurred, widened

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. a. Patient is too far forward/too far back on the bite block: Patient too far back: anterior teeth will be ___ and ___.

blurred, narrowed

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. a. Patient is too far forward/too far back on the bite block: Patient too forward in the focal trough: anterior teeth will be ___ and more ___.

downward, mandibular, anterior, condyles, exaggerated, parallel

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. b. Patient's chin is tilted down: Problem. If the patient is positioned such that the chin is too low or is tipped down, the Frankfort plane is angled ___, and the following results: 1. The ___ incisors appear blurred. 2. A loss of detail in the ___ apical region occurs. 3. The mandibular ___ may not be visible. 4. An "___ smile line" (curved upward) is seen on the image. Solution. To prevent such an error, the dental radiographer must carefully position the patient such that the Frankfort plane is ____ to the floor.

upward, superimposed, incisor, blurred, reverse parallel

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. b. Patient's chin is tilted up: Problem. If the patient is positioned such that the chin is too high or is tipped up, the Frankfort plane is angled ___, and the following results: 1. The hard palate and floor of the nasal cavity appear ___ over the roots of maxillary teeth. 2. A loss of detail in the maxillary ___ region occurs. 3. The maxillary incisors appear ___ and magnified. 4. A "____ smile line" (curved downward) is seen on the image. Solution. To prevent such an error, the dental radiographer must carefully position the patient such that the Frankfort plane is ___ to the floor.

blurring, jaw

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. c. Patient moves during exposure or contacts the cassette: causes ___, but not on entire film necessarily. May also cause a discrepancy of the alignment of structures within the ___.

closed, anterior, palate, apices; lips, swallow

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. d. Tongue is not in proper position: Problem. If the patient's lips are not ___ on the bite-block during the exposure of a panoramic projection, it results in a dark radiolucent shadow that obscures ___ teeth. If the tongue is not in contact with the ___ during the exposure of a panoramic projection, it results in a dark radiolucent shadow that obscures the ___ of the maxillary teeth. Solution. To prevent such errors, the dental radiographer must instruct the patient to close the ___ around the bite-block. The patient must then be instructed to ___ once; after this, the patient must be asked to raise the tongue up to the palate and hold it against the hard palate during the exposure of the projection.

radiopaque cone; thyroid collar

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. e. Lead apron artifact: Problem. If the lead apron is incorrectly placed on the patient, or if a lead apron with a thyroid collar is used during the exposure of a panoramic projection, it results in a ___ ____-shaped artifact that obscures diagnostic information. Solution. To prevent such an artifact, the dental radiographer must always use a lead apron without a ___ ____ when exposing a panoramic projection. The lead apron must be placed low around the neck of the patient so that it does not block the x-ray beam.

metallic or radiodense; twice; remove

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. f. Ghost images Problem. If all ___ or ____ objects (e.g., eye glasses, earrings, necklaces, hairpins, removable partial dentures, complete dentures, orthodontic retainers, hearing aids, napkin chains) are not removed before the exposure of a panoramic receptor, it results in a ghost image that obscures diagnostic information. A ghost image, which is a radiopaque artifact seen on a panoramic image, is produced when a radiodense object is penetrated ____ by the x-ray beam. A ghost image resembles its real counterpart and is found on the opposite side of the image; it appears indistinct, larger, and higher than its actual counterpart. For example, a ghost image of a hoop earring appears on the opposite side of the image as a radiopacity that is larger and higher than the real hoop earring. In addition, the ghost image of the hoop earring appears blurred in both horizontal and vertical directions. Solution. To avoid such an artifact, the dental radiographer must instruct the patient to ____ all radiodense objects in the head-and-neck region before positioning the patient for panoramic radiography.

ramus, posterior, magnified; perpendicular, midline

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. g. Patient's head is rotated to the right/left Problem. If the patient's head is not centered, the ___ and ___ teeth appear unequally magnified on the panoramic image. The side farthest from the receptor appears ____, and the side closest to the receptor appears smaller. Solution. To prevent such an error, the dental radio- grapher must position the patient's head such that the midsagittal plane is ___ to the floor while the ___ is centered on the bite-stick. The lateral head supports must then be adjusted to stabilize the position of the patient's head.

radiopacity, straight

7. Describe the appearance of panoramic films when the following common errors are made in exposure. State how to avoid/correct these errors. h. Patient is not erect/straight spine Problem. If the patient is not standing or sitting with the spine straight, the cervical spine appears as a triangular ___ in the center of the image and obscures diagnostic information. Solution. To prevent such an error, the dental radiographer must instruct the patient to stand or sit "as tall as possible" with a ____ back.

A

7. This type of image is used to examine the extent of large lesions. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

A

8. The dental arches must be aligned to the focal trough. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

C

9. The tubehead contains a filament used to produce electrons and a target used to produce x-rays. a. Panoramic imaging b. Intraoral imaging c. Both panoramic and intraoral imaging

vertical, continuous, 4

Explain/compare radiation dose of Pano to BWX films: • The x-ray beam is collimated to a ___ slit that is usually 1-2mmX30mm • A ____ exposure of x-ray is emitted while the tube head is rotating for approx. 15-22 seconds & intensifying screens are used with film • Patient exposure is approximately the same as ___ BWX