Download - Projection Geometry
![Page 1: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/1.jpg)
PROJECTION GEOMETRY
Dr. Kristina Corazon L. Robles
![Page 2: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/2.jpg)
Ideal results:Sharp imageTrue Shape & Size of the object
Principles of Image Formation
![Page 3: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/3.jpg)
Terminologies
Sharpness- measures how well a boundary between two areas of differing density is revealed.
Spatial resolution- measures how well small objects that are close together can be seen
![Page 4: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/4.jpg)
Terminologies
Image size distortion (magnification)1. film and object not parallel to each
other2. smaller focal - object distance. (short
cone)3. central beam not at 90 degrees to
object.
Image shape distortion is the result of unequal magnification of different parts of the same object.
![Page 5: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/5.jpg)
5 Fundamental Principles
1. Small radiation source / focal spot2. Target-film-distance long as practical3. Object-film-distance short as possible4. Parallel film to long axis of teeth5. Perpendicular alignment of beam to
film & objects
STOPP!!!
![Page 6: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/6.jpg)
INTRAORALRADIOGRAPHIC
TECHNIQUES
![Page 7: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/7.jpg)
Types of Intraoral Radiographic Examination
1. Periapical ExaminationPurpose used to examine the entire tooth and
supporting bone Film type- periapical film Technique - paralleling technique and
bisecting angle technique
![Page 8: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/8.jpg)
Types of Intraoral Radiographic Examination
1. Periapical Examination
![Page 9: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/9.jpg)
Types of Intraoral Radiographic Examination
2. Interproximal ExaminationPurpose used to examine the crowns of
opposing teeth on a single film; used in examining adjacent tooth surfaces and crestal bone
Film type- bitewing film Technique-bitewing technique
![Page 10: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/10.jpg)
Types of Intraoral Radiographic Examination
2. Interproximal Examination
![Page 11: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/11.jpg)
Types of Intraoral Radiographic Examination
3. Occlusal ExaminationPurpose used to examine large areas of
maxilla and the mandible Film type- occlusal film Technique- occlusal technique
![Page 12: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/12.jpg)
Types of Intraoral Radiographic Examination
3. Occlusal Examination
![Page 13: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/13.jpg)
![Page 14: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/14.jpg)
Paralleling Technique
![Page 15: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/15.jpg)
Paralleling Technique
Film placed parallel to long axis of teeth
Beam directed perpendicular to film & long axis of teeth
Film holder used to keep film flat & unbent
Long PID or TFD to offset increased magnification due to great OFD
![Page 16: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/16.jpg)
Paralleling Technique
![Page 17: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/17.jpg)
![Page 18: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/18.jpg)
Bisecting Angle Technique
![Page 19: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/19.jpg)
Bisecting Angle Technique
Cieszynski ’ s Rule of Isometry
Rule of Isometry- 2 triangles are (=) if they have two (=) angles and share a common side
Film placement- Lingual surface
![Page 20: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/20.jpg)
Bisecting Angle Technique
1. Horizontal Angulation
Correct- central ray is directed perpendicular to the curvature of the arch and through the contact areas leading to open contact areas
X Incorrect - results in and overlapped interproximal contact areas
![Page 21: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/21.jpg)
Bisecting Angle Technique
2. Vertical Angulation
![Page 22: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/22.jpg)
Bisecting Angle Technique
Video
![Page 23: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/23.jpg)
Foreshortening
![Page 24: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/24.jpg)
Elongation
![Page 25: Projection Geometry](https://reader036.vdocuments.net/reader036/viewer/2022062520/5695d0df1a28ab9b02943415/html5/thumbnails/25.jpg)
Seatwork: (by group)
1. Draw the diagram of paralleling technique and bisecting angle technique
2.State the advantages and disadvantages of each.
3. Draw the components of a dental xray film. Label and describe the functions of each.
4.Indicate the uses of each size of the film. (size 0, 1, 2, 4)
5. Describe the uses of a developer and a fixer.