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Panoramic Imaging
Dental Radiography -- Principles and Techniques
Term | Definition |
---|---|
Panoramic Imaging | wide view of MX and MD |
Purpose | eval impacted teeth eval eruption patterns, growth, and development detect disease, lesions, and conditions of jaw extent of large lesions eval trauma |
Fundamentals | xray tube rotates arounf PT head in one direction while recptor rotates in opposite direction ... creates tomography |
Tomography | allows imaging of one layer/section of body while blurring images of structures in other planes |
Rotation Center | Pivotal point or axis around where the receptor and xray tube head rotate |
3 Basic Rotation Center | 1. dbl center 2. trpl center 3. moving center |
Focal Trough | theoretical concept used to determine where dental arches must b positioned to obtain clearest image |
Vertical Angulation | tube head always rotates behind PT head receptor always rotates in front of PT |
Head Positioner | consists of chin rest, bite-block, forehead rest, and lateral head supports |
Film | blue- sensitive -- paired w screens that produce blue light green-sensitive -- paired w screens that produce green light |
Intensifying Screens -- Calcium Tungstate | emit blue light |
Intensifying Screens -- Rare Earth | -emit green light -require less xray exposure -faster |
Cassette | device that holds extra-oral films and intensifying screens |
Ghost Image | -if not all metallic/radiodense objects are not removed -radiopaque artifact seen on pano image |
Lead ApronArtifact | - occurs if lead apron is improperly placed - radiopaque cone-shaped artifact |
Positioning of Lips and Tongue | - dark radiolucent shadow that obscures ant teeth - if tongue doesnt remain on palate, dark radiolucent shadow appears |
Positioning of Frankfort Plane Upward | - chin too high or is tipped up, frankfort plane is angled upward -- results in reverse smile line |
Positioning of Frankfort Plane Downward | - chin too low or tipped down -- exaggerated smile line |
Aligning Teeth Ant to Focal Trough | - PT teeth too far forward on bite-block or ant to focal trough - ant teeth appear skinny |
Aligning Teeth post to Focal Trough | - Pt ant teeth are aligned too far back on bite-block - teeth appear fat |
Aligning Midsagittal Plane | - PT head not centered - ramus and post teeth appear unequally magnified |
Aligning the Spine | - PT not standing w spine straight - cervical spine appears as a radiopacity in the center of mage |
Advantages of Pano Imaging | field size simplicity PT cooperation Min exposure |
Disadvantages of Pano Imaging | image quality focal trough limitations distortion equpitment cost |