DENT 506 Panoramic Radiographs
About this set
Created by:
KTay1127 Plus on March 15, 2012
Log in to favorite or report as inappropriate.
Order by
39 terms
Terms | Definitions |
|---|---|
 Focal Trough | Only region that will be in focus Narrower in anterior, wider in posterior -Critical that patient's teeth be located in focal trough -Placement of anterior teeth particularly important |
| Panoramic Radiograph: Narrow Beam | Beam of very narrow width is allowed to rotate about the point where the X-ray source was previously located. |
| Vertical Dimension | In the vertical dimension, the magnification is calculated by dividing the distance from the X-ray source to the film by the distance from the X-ray source to the object. |
| Horizontal Dimension | In the horizontal dimension, since the focus is different, it is calculated by dividing the distance from the intraoral rotation center to the film by the distance from the rotation center to the object. This makes the magnification factor much greater in the horizontal than in the vertical dimension and leads to the peculiar image. |
| Critical steps for producing radiograph of diagnostic quality | Prepare machine Prepare patient Position patient properly Expose film properly Process film properly |
| Prepare machine | -Disinfect all parts touched by patient -Place sterile bite-pin or plastic bag over non-removable bite-pin -Load cassette with film and position appropriately in cassette holder -Adjust height of machine -Select exposure factors |
| Prepare Patient | -Ask patient to remove all jewelry in the head and neck (earrings, lip and tongue rings, necklaces), as well as dental appliances, hearing aids, etc -Drape patient with leaded apron -Tell patient what to expect during procedure |
| Remove All Metal Jewelry and Appliances | Images of metal objects show up as "ghosts" on opposite side of image |
| Drape patient with leaded apron | Two-sided aprons frequently used Thyroid collars are not used because they interfere with image |
| Position Patient Correctly | Anterior-posterior position Occlusal plane Cervical Spine straight Tongue to roof (palate) of mouth -Machine manufacturers try to make this simple and repeatable -Lights shine on face to guide position -Head holders -Must check details for specific machines in owner's manual -Basic principles same for all machines |
| 3 Positioning Lights | 1. Frankfort (horizontal) 2. Midline (midsagittal; look at whole face not just nose) 3. Focal trough (anterior-posterior) |
| Frankfort (Occlusal) Plane | - From floor of orbit (eye socket) to external auditory meatus (ear canal) - Must be parallel to floor - Can also use ala (wing) of nose to tragus (triangle) of ear at 5 degrees downward - Move chin up or down to adjust -Radiograph shows a gentle smile if occlusal plane correct -Keeps roots of maxillary teeth away from shadow of hard palate |
| Midsagittal | Midline, from forehead through nose to chin Must be perpendicular to floor Must be in midline of x-ray machine (head not rotated) |
| Focal trough (anterior-posterior position) | Must put teeth in focal trough Patient bites in groove of bite-pin Midsagittal plane vertical No rotation of head Chin support for edentulous patients |
| Panoramic Positioning Errors | Too Far Anterior Teeth in front of focal trough are shrunken More of a problem in anterior than posterior Too Far Posterior Teeth behind focal trough are enlarged More of a problem in anterior than posterior |
| Incorrect Occlusal Plane: Beam Too Far Down | Patient's head tipped down too much Image is distorted An "exaggerated smile line" is seen on a panoramic film when the patients chin is tipped down. |
| Incorrect Occlusal Plane: Beam Too Far Up | Patient's head not tipped far enough Occlusal plane too flat Image is distorted Maxillary roots covered by palate A "reverse smile line" is seen on a panoramic film when the patients chin is tipped up. |
| Positioning: Spine Straight | -Normal cervical spine is curved -Spine must be straight to minimize shadow on radiograph -Ask patient to move feet forward so spine will straighten -Must hold on to handles on machine to avoid falling -No unwanted spine shadow -Anterior teeth seen clearly |
| Positioning: Spine Not Straight | Unwanted white shadow covering anterior teeth May be a problem for patients with short or stiff neck or patient in wheelchair The more non-straight the larger the ghost image If the patient is not standing erect, superimposition of the ghost image of the cervical spine (arrows) may be seen on the center of the panoramic film. |
| Tongue to roof of mouth | Squeeze air out between tongue and palate "Like peanut butter is holding your tongue up there" Have the _entire_ tongue on the roof of the mouth for the entire exposure |
| Tongue not to roof of mouth | Black air shadow above tongue covers roots of teeth Air spaces will be displayed as black shadows on film |
| Proper Panoramic Exposure | Correct machine settings based on patient size Verify patient positioning Ask patient to swallow and put tongue to roof of mouth Caution patient to hold still Depress exposure switch for entire cycle (15-20 seconds) Cannot change the exposure time. What we can change is the kVP and Ma. |
| Ghost Images | Larger Blurrier Opposite side Higher up Closer to the midline |
| Incorrect Lead Apron Block | On a panoramic radiograph, a lead apron artifact appears as a large cone-shaped radiopacity obscuring the mandible. |
| Incorrect Tongue Placement | If the tongue is not placed on the roof of the mouth, a radiolucent shadow will be superimposed over the apices of the maxillary teeth. |
| Patient Positioning: Too Far Forward | The anterior teeth appear narrowed and blurred on a panoramic film when the patient is positioned too far forward on the bite-block. |
| Patient Positioning: Too Far Back | The anterior teeth appear widened and blurred on a panoramic film when the patient is positioned too far back on the bite-block. |
| Patient Positioning: Head Not Centered | The patients posterior teeth and ramus appear to be magnified on a panoramic film when the head is not centered. |
| Panoramic Concepts: Midline | Midline structures may be projected as single and/or double images Diamond shaped midline area that produces double images |
| Real vs. Ghost Image | Real: located between film, center of rotation Ghost: located between center of rotation, x-ray source |
| Soft Tissue in Panoramics | Soft palate Tongue Lips Nasolabial fold Earlobe Turbinates |
| Air Spaces | Between tongue and hard palate -Nasopharynx -Oropharynx --May not be symmetrical if patient swallows during scan! |
| Anatomic Variants: Medial sigmoid depression | Osseous depression in medial portion of ramus at sigmoid notch May be unilateral or bilateral |
| Anatomic Variants: Hyperplastic Tonsils | Soft palate looks much larger than normal elliptical shape |
| Anatomic Variants: Panoramic anterior median radiolucent pseudolesion | "president's tumor" Prominent midline depression located in focal trough |
| Anatomic Variants: Spine of sphenoid bone | Special TMJ program seen here Radiopacity on top of condyle |
| Anatomic Variants: Ear Canal & Condyles | Ear canal superimposed over condyles Verified with open mouth view Condyle moved, "lesion" did not Condyle has air in it so will show a radioleucency |
| TMJ Gross Changes Can Be Observed | Flattening Erosion Subchondral sclerosis Osteophytes Fractures Tumors Asymmetry (hypo- or hyperplasia) |
| Maxillary sinus findings | Cloudiness / opacification (sinusitis) Mucous retention pseudocysts Mucoceles Polyps (may even erode the floor of sinus walls) Sinus pneumatization (floor scallops between roots) Look for symmetry, follow the floor of the sinus! |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.