Tomography

1. Definition: specialized technique for producing radiograph of only a slice of the patient

1.1. Each Tomograph has focal trough:3d Image layer tissue in this section sharply defined and in focus and revealed clearly in final image

1.2. Focal plane level: height of focal plane above table

1.3. structures outside are blurred

2. Clinical Applications

2.1. 1. Assessment of jaw height, thickness and texture before inserting implant1.

2.2. 2.Postoperative evaluation of implants

2.3. 3. Assessment of the size, position and extent of antral tumours

2.4. 4. Evaluation of grossly comminuted facial fractures to determine all the fracture sites

2.5. 5. Assessment of the extent of orbital blow-out fracture

3. Machine

3.1. X ray tube

3.2. xray film under table

3.3. rigid connector between them rotates around fulcrum

4. Movements

4.1. Linear • Circular • Elliptical • Spiral • Hypocycloida

5. Tomographic angle

5.1. GREAT angle = thin section; more than 10 = used in high contrast bone

5.2. narrow angle = thick section upto 25mm ;less than 10= zonography in low contrast soft tissue = zonography