Download JCEG V summary statements

Superimpositions2D Superimpositions:
Can be implemented on screen in some commercially
available software such as Dolphin however, some
modifications to existing software systems would insure
that these systems would find use in Orthodontic
departments for the purpose of training residents in
cephalometric analysis and superimposition.
Specifically JCEG would recommend the following
features to insure that a software program would meet
the needs of academic institutions’ teaching mission:
1. The ability to locate four corner Baumrind fiducials
on scanned cephalograms and the ability to place
fiducials permanently on digital cephalometric
images. The technical specifications for fiducials will
be supplied by the CRIL Team.
2. When two tracings are superimposed the
relationships among the four pairs of fiducial
landmarks should be preserved.
3. The ability to use a “Wacom Type” tablet to draw
lines on the computer display much like using a pencil
on tracing paper. In the future, touch screen
technology may eliminate the need for the tablet.
4. The ability to superimpose the tracings on these
lines without regard to actual landmark location. And
the ability to use these free hand lines for regional
as well as Cranial Base superimposition.
5. Free hand lines should be independent of landmark
locations. Thus, cephalometric analysis would use
landmark locations and superimpositions could use
the free hand lines.
JCEG would like to emphasize that traditional
cephalograms generate a prospective image and current
native digitally captured cephalometric images are not
prospective but are orthogonal images. This means that
linear measures from standards generated from
traditional films may not apply. NB It is important to
have machine calibration checked periodically to insure
that the image is not distorted. When generating
cephalograms from 3D CBCT, most systems allow both
orthogonal and prospective images to be created. JCEG
recommends using the orthogonal image if both images
are generated from 3D data. The only reason to use the
prospective image is when you want to compare a
traditional (i.e. plane film not digital cephalogram) to a
CBCT generated cephalometric image. And when creating
a prospective image from CBCT data you need to match
the source object distance and object cassette distance
to match the cepholostat that was used to generate the
traditional cephalogram.
Because the Bolton Standards created by Bill Golden
used the Bolton orientator, the standards are orthogonal
to the extent that the central ray actually passed
through the machine porion axis. (A reasonable
assumption).
Tolerances for research should approach 0.1 mm because
the results of research influence clinical treatment
decision making.
3D Superimpositions:
To the extent possible, 3D superimposition must
incorporate what is known about the biology of facial
growth.
At the present time open source software tools are
available for superimposition but are not “user friendly”.
Commercial software that is more “user friendly” may not
be as accurate or give consistent results.
There are still uncertainties about how to transfer what
is known about accurate 2D superimposition to the 3D
environment.
3D Morphologic StandardsTemplate analysis may find renewed interest in the
digital environment since the limitations of size variation
and saving the superimposition of the template over the
image are both easily solved with digital media.
Linear and angular measures are useful for quantitative
studies.
Registration of images is critical in 3D for comparisons
between individuals within individuals through time. It is
also important that this frame of reference can be saved
and that the origin can be specified within the image
volume and that the origin can be changed to facilitate
different analyses.
Surface 3D scans is the new term for next year for this
working group. This term was changed to include Digital
Study Casts and 3D facial scans.
The technology has evolved rapidly resulting in reduced
cost of hardware bringing the technology within reach of
the average practitioner. CAD CAM orthodontic
appliances are likely to widely used within the next three
years. And, as 3D facial scans approach 300dpi resolution
they are likely to replace digital photography within 5
years.
Nomenclature/Terminology- This working group has been
placed on hold until further notice.
Image Quality and Machine Parameters- What is the role
of 2D imaging in a 3D world?
2D imaging is still valuable. JCEG endorses the “Image
Gently” program and supports the position paper
developed jointly by AAO members and maxillofacial
radiologists.
Database of 3D CT images- Shelly Baumrind and the
Legacy Collection. A formal demonstration of the
Legacy project will be included in next years JCEG
agenda.