Problens with ORTOPHOS (SIEMENS)
ASingh at PRODIGY.NET
Sat Apr 15 14:08:21 PDT 2000
Hello Dr. Nilson:
A similar question was raised a couple of years ago, which I had responded
to. I am copying the text of that response below:
Your experience is typical of almost any user who tried
to use transversal slicing in a pure panoramic machine.
Regardless of the positioning method or the aiming
device, the underlying problem is the method used to
produce slices in these systems. The typical panoramic
motion is used to produce these slices, which inherit
all the limitations of a pan image: variable and
unpredictable magnifications in horizontal and
vertical directions, very thick slices, unwanted
superimpositions from objects far away from the desired
focal plane, etc. These difficulties are
even more exaggerated in the anterior regions.
Although panoramic images can be called tomographic
images in the general sense of the word, but in the
practical sense the word is used, they don't qualify.
Of course, a pan image is very useful for what it is
intended, but this method falls way short when used
to gather other types of information where true
tomographic images are warranted, e.g. sections of
the mandible or maxilla for implant planning.
Linear tomography is superior to panoramic type
tomography, as the image is produced via a "tomographic"
motion. It lacks some of the crippling limitations of
panoramic type images, however, many limitations still
remain. Some of the limitations are streaking on the image,
unpredictable slice thickness when the bone is oriented
in the same direction as the tomographic motion
(sometimes showing objects far away from the focal plane)
and unwanted superimpositions. The most accurate and "true"
tomographic slices are produced via a "complex"
tomographic motion (e.g. Hypocycloidal and spiral) using
the Grossman Technique. Non-Grossman complex motion systems
are a close second.
An analogy I heard from someone in a cocktail party is
appropriate here: If someone wants to learn about a city,
then there are 3 possible ways: Taking the bypass around
the city is analogous to panoramic tomography, driving
straight through the city on one road is tantamount to
Linear Tomography, and really going around the city taking
various streets and seeing all the important landmarks is
like complex motion tomography.
With the introduction of computer automation and
sophisticated software, the high end complex motion
systems far surpass other modalities in
versatility and quality.
Dr. Nilson: I would like to add that a Dental Radiology
Clinic named "IBRO" provides excellent tomographic imaging
service to area doctors in your city (Salvador, Brazil). This
clinic utilizes the CommCAT Imaging System, which is a
true complex motion tomographic imaging equipment. They
also include an Oral Radiologist's report with the radiographs.
Imaging Sciences has also introduced a smaller, less expensive
and simplified Panoramic and complex motion Tomographic
Imaging System, named Panorex CMT.
Imaging Sciences International
Arun at ImagingSciences.com
From: Nilson Pena Neto Segundo <nilson at IG.COM.BR>
To: ORADLIST at listserv.ucla.edu <ORADLIST at listserv.ucla.edu>
Date: Wednesday, April 12, 2000 12:10 AM
Subject: Problens with ORTOPHOS (SIEMENS)
Does anyone have any experience with ORTHOPHOS PLUS CD (SIEMENS)
We are having problens with the transverse tomography exposure, used in
implantology. The images are bad, and don't permit a reliable diagnostic.
We suppose that our equipment could be damaged, or SIEMENS is selling a
machine that doesn't work properly.
Dr. Nilson Pena
Salvador (Ba) - BRAZIL
nilson at ig.com.br
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