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1. COMPUTERISED CEPHALOMETRIC
SYSTEMS:
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2. The manual technique of tracing a cephalogram is time
consuming and tedious.
In comparison computerized cephalometry is very fast and takes
just 10% of the time a manual tracing requires.
Due to direct digitization of the landmarks the process removes
human errors except those of landmark identification.
In addition to speed computerized cephalometry also facilitates
the use of double digitization of landmarks thus significantly
increasing the reliability of the analysis.
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3. Other benefits of this method include:
•Easy storage and retrieval of cephalometric values and tracings
•Intergration of the cephalometric registrations within an office
management computerized sytem.
•Combinationof the cephalometric data with patients files photos and
dental casts.
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4. Three possible approaches may be used to perform a cephalometric
analysis.
1. The most common method is by manually placing a sheet of
acetate over the cephalometric radiograph, tracing salient
features, identifying landmarks, and measuring distances and
angles between landmark locations.
2. Another approach is computer aided. Landmarks are located
manually while these locations are digitized into a computer
system. The computer then completes the cephalometric
analysis.
3. The third approach is completely automated. The cephalometric
radiograph is scanned into the computer. The computer
automatically locates landmarks and performs the
cephalometric analysis.
(Rudolph, Sinclair,AJO 1998)
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5. Currently, several commercially available systems can perform
basic cephalometric analysis tasks.
The user locates landmarks manually with a mouse cursor on
the display monitor on some systems. Other systems digitize
landmark locations on a digitizing pad. In either case a
computer algorithm performs a cephalometric analysis by
calculating distances and angles between landmark locations.
In addition, the algorithm connects these landmarks with line
segments to produce a tracing. Some systems are capable of
moving the tissues to simulate treatment effects, growth
effects, and surgical prediction. Finally, some of these systems
also are able to produce a time series of images using landmark
locations, not superimposition contours, to register images.www.indiandentalacademy.com

6. Generally, these systems do not save time, are expensive,
and require technical training. The accuracy of these
computer-aided programs has been demonstrated to be
similar to that of manual digitization, and because manual
landmark identification programs require subjective user
point identification, they are limited in scope.
In addition, the number of landmarks required are high; this
tends to negate any time saved using this method. Although
the analysis uses a computer, the process of manual point
digitization can be time-consuming and error-prone.
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7. Automatic Landmark Identification
A third approach to cephalometric
analysis is completely automated. The
cephalometric image is scanned into a
computer and both landmark
identification and cephalometric
analysis are automated.
The process has the potential to
increase accuracy, provide more
efficient use of clinicians' time, and
improve our ability to correctly
diagnose orthodontic problems.
Additionally, this process may provide mathematical descriptions
of landmark locations that could be applied to new ways of
evaluating cephalometric radiographs to derive clinically
important information.www.indiandentalacademy.com

8. Digitized cephalometry
– Dentofacial planner
– Quick ceph image
– Por dios
– Digigraph
– Rocky mountain orthodontics – JIFFY
orthodontic evaluation
– Prescription planner.
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9. DIGITAL RADIOGRAPHY
• A digital image is a matrix of square pieces or picture elements (pixels), that
form a mosaic pattern from wherein original image can be reconstructed for
visual display.
Analog Image Digital Image
• 1) Conventional radiographic 1) a) Light sensitive
Image elements to record
the image.
b) Shades of gray to
display the Image
• 2) Silver halide grain 2) Light sensitive
elements
• 3) Randomly dispersed 3) Regular grid of rows
and Columns
• 4) Continuous Spectrum 4) Numeric and Discrete.
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10. PIXELS AND VOXELS
• Pixel
2-D Digital Images – Composed of Picture elements.
• Voxel
3-D Digital Images – Composed of volume elements.
PRODUCTION OF DIGITAL IMAGE
Analog to Digital conversion (ADC).
• Sampling - Small range of voltage values grouped
together.
• Quantization - Every sampled signal is assigned a value.
Pixels are arranged in proper locations and given a
shade of gray corresponding to quantization
number.
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11. Advantages;
• It is very fast.
• It is only necessary to digitise the points directly on
the cephalogram and calculations are done in
seconds.
• It removes human error
• Facilitates use of double digitisation of landmarks,
thus increasing reliability.
• Easy storage and retrieval of values.
• Simultaneous demonstration of anatomical
structures of different thickness--i.e., bone and soft
tissues--and its lower exposure dose make digital
radiography the diagnostic procedure of choice in
cephalometrics.
• Filmless imaging.
• Patient education.
• Better treatment planning.
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