DHG 121 PANORAMIC RADIOGRAPHY Objectives: 1. Discuss the advantages and disadvantages of the panoramic radiograph. 2. Discuss the type of film needed for panorex. 3. Identify by written or oral means, the various parts of a panoramic unit. 4. Discuss the rationale uses for the panorex or panoral. 5. Identify normal anatomic radiographic landmarks on a panoramic radiograph. 6. Define and explain the term focal trough. 7. Discuss the various types of cassettes and the reason for using one. I. IMAGE PRODUCTION II. TYPES A. Split Image B. Continuous Image III. USES IV. FILM AND FILM SCREENS V. ADVANTAGES OF THE PANORAMIC RADIOGRAPH VI. DISADVANTAGES VII. TECHNIQUE VIII. ERRORS IN TECHNIQUE IX. PROCESSING IX. CASSETTES X. INTENSIFYING SCREENS DHG 121 PANORAMIC RADIOGRAPHY Objectives: 1. Discuss the advantages and disadvantages of the panoramic radiograph. 2. Discuss the type of film needed for panoramic radiograph and processing methods. 3. Identify by written or oral means, the various parts of a panoramic unit. 4. Discuss the rationale uses for the panorex or panoral. 5. Identify normal anatomic radiographic landmarks on a panoramic radiograph. 6. Define and explain the term focal trough. 7. Discuss the various types of cassettes and the reason for using one. 8. Explain the use of intensifying screens, types and significance. 9. Discuss the technique of taking panoramic radiographs and errors in technique. 10. Define the two types of panoramic radiographs: split and continuous image. I. IMAGE PRODUCTION based on principle of tomography - recording selected layers of body tissue on radiographic film while blurring out other areas II. TYPES A. Split Image - film has a clear area down middle where cassette stopped and restarted - anterior teeth appear on both sides B. Continuous Image- one continuous image on film - no duplication of anterior teeth III. USES - mass surveys - edendulous - trismus - children IV. ADVANTAGES OF THE PANORAMIC RADIOGRAPH - visualizes entire dentition, tmj - easy to perform - no patient discomfort - less time to expose than a fmx - good tool for patient education V. DISADVANTAGES - lack of detail of the periodontium - overlapping of teeth in anterior - overused - ghost images superimposed over structures VI. FOCAL TROUGH - the area in focus , patient must be positioned within focal focal trough so that teeth and other structures are in focus VII. TECHNIQUE - lead apron position depends on machine (no thyroid collar) - no metal from neck up - remove all removable appliances - must have teeth separated with bite block or cotton roll - frankfort plane must be parallel to floor - patient must be upright - have patient push tongue up against the roof of the mouth VIII. ERRORS IN TECHNIQUE - patient too far forward ( in front of focal trough , which puts them closer to the film) = anterior teeth blurred and diminished in width - patient too far back (behind focal trough, and farther from the film) = anterior teeth blurred and magnified - chin tipped too low = exaggerated smile - chin tipped too high = frown appearance and apices of maxillary teeth cut off - head rotated = one side small, the other magnified - patient slumped = ghost image of spine superimposed over chin - lead apron = clear area - tongue not against roof of mouth = radiolucent image over maxillary apices IX. FILM AND PROCESSING - extraoral, screen film - 5 X 12 and 6 X 12 - in regular solutions - extraoral film sensitive to light, must process in dark or have proper safelight filter X. CASSETTES - purpose is to protect film from exposure to light - can be rigid or flexible and curved or flat XI. INTENSIFYING SCREENS -* purpose is to intensify radiation, thus allowing a decrease in exposure time - image is a result of indirect exposure to x-radiation - radiation hits screen and causes it to fluoresce and emit light which exposes film - coated with phosphorescent crystals 1. calcium tungstate crystals - emit blue light 2. rare earth (Lanex) crystals - emit green light (less exposure time required - important to match screens with film that is sensitive to the light that they omit - screens must be light tight
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