Image analysis – Applications – Biomedical applications
Reexamination Certificate
2000-07-13
2003-03-11
Johns, Andrew W. (Department: 2621)
Image analysis
Applications
Biomedical applications
C382S154000
Reexamination Certificate
active
06532299
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to scanning anatomical structures for various uses, and more specifically, to scanning anatomical structures to treat and diagnose, as well as develop and manufacture medical and dental devices and appliances.
BACKGROUND OF THE INVENTION
The ability to generate anatomical devices such as prosthetics, orthotics, and appliances such as orthodontics is well known. Current methods of generating anatomical devices is subjective, whereby a practitioner specifies, or designs, the anatomical device based upon subjective criteria such as the practitioner's view of the anatomical structure, the location where a device is to be used, and the practitioner's experience and recall of similar situations. Such subjective criteria results in the development of an anatomical device that can vary significantly from practitioner to practitioner, and prevents the acquisition of a knowledge database that can be used by others.
One attempt to make the development of an anatomical devices less subjective includes taking an impression of the anatomical structure. From the impression, which is a negative representation of the anatomical structure, a positive model of the anatomical structure can be made. However, impressions, and models made from impressions, are subject to distortion, wear, damage, have a limited shelf life, are imprecise, require additional cost to generate multiply copies, and have an accuracy that is not readily verifiable. Therefore, whether an impression or a model of a structure is a true representation of the anatomical structure is not readily verifiable. Furthermore, impression processes are generally uncomfortable and inconvenient for patients, require a visit to a practitioner's office, and are time consuming. Furthermore, where multiple models are needed, either multiple impressions must be made, or multiple molds must be made from a single impression. In either case, no reliable standard reference is available to guarantee the similarity of each of the models. Furthermore, the mold still must be visually interpreted by the solo practitioner, resulting in a subjective process.
Another attempt to make development less subjective includes using two-dimensional images. However, the use of 2-dimensional images as known can not provide precise structure information, and still must be objectively interpreted by the practitioner. Furthermore, the manufacturing of the device is still based upon an objective interpretation.
When an impression is shipped from the practitioner to a manufacturing facility, communication between the practitioner and the technicians about issues pertaining to the model or device being manufactured is impeded, since the three-dimensional model which is being used to design a prosthetic device is available only to the manufacturing facility. Even if multiple molds exist, they can't be viewed simultaneously from the same perspective, as they are physically separate objects, nor is there an interactive way of referencing the multiple models to one another.
Other types of records, in addition to molds and impressions, that maintained by practitioners, such as dentists and orthodontists are subject to being lost or damaged, and are costly to duplicate. Therefore, a method or system that overcomes these disadvantages would be useful.
The use of scanning techniques to map surfaces of objects is well known. Prior art
FIG. 1
illustrates an object
100
having visible surfaces
101
-
104
. Generally, the visible surfaces
101
-
103
form a rectangular shape residing on top of a generally planer surface
104
.
Projected onto the object
100
is an image, which includes the line
110
. In operation, the image of line
110
is received by a viewing device, such as a camera, (not shown) and processed in order to determine the shape of that portion of object
100
where the line
110
resides. By moving the line
110
across the object
100
, it is possible to map the entire object
100
. Limitations associated with using an image comprising a single line
110
is that a significant amount of time is needed to scan the object
100
to provide an accurate map, and a fixed reference point is needed at either the scanner or the object.
FIG. 2
illustrates a prior art solution to reduce the amount of time taken to scan an object. Specifically,
FIG. 2
illustrates an image including lines
121
through
125
. By providing multiple lines, it is possible to scan a greater surface area at once, thus allowing for more efficient processing of data associated with the object
100
. Limitations of using patterns such as are illustrated in
FIG. 2
include the need for a fixed reference point, and that the surface resolution capable of being mapped can be reduced because of the potential for improper processing of data due to overlapping of the discrete portions of the image.
In order to better understand the concept of overlapping, it is helpful to understand the scanning process. Prior art
FIG. 3
illustrates the shapes of
FIGS. 1 and 2
from a side view such that only surface
102
is visible. For discussion purposes, the projection device (not illustrated) projects a pattern in a direction perpendicular to the surface
101
which forms the top edge of surface
102
in FIG.
3
. The point from the center of the projection lens to the surface is referred to as the projection axis, the rotational axis of the projection lens, or the centerline of the projection lens. Likewise, an imaginary line from a center point of the viewing device (not shown) is refereed to as the view axis, the rotational axis of the view device, or the centerline of the view device, extends in the direction which the viewing device is oriented.
The physical relationship of the projection axis and the view axis with respect to each other is generally known. In the specific illustration of
FIG. 3
, the projection axis and the view axis reside in a common plane. The relationship between the projection system and the view system is physically calibrated, such that the relationship between the projector, and the view device is known. Note the term “point of reference” is to describe the reference from which a third person, such as the reader, is viewing an image. For example, for
FIG. 2
, the point of reference is above and to the side of the point that is formed by surfaces
101
,
102
, and
103
.
FIG. 4
illustrates the object
100
with the image of
FIG. 2
projected upon it where the point of reference is equal to the projection angle. When the point of reference is equal to the projection angle, no discontinuities will appear in the projected image. In other words, the lines
121
-
125
appear to be straight lines upon the object
100
. However, where the point of reference is equal to the projection axis, no useful data for mapping objects is obtained, because the lines appear to be undistorted.
FIG. 5
illustrates the object
100
from a point of reference equal to the view angle fleet of FIG.
2
. In
FIG. 5
, delayed the surfaces
104
,
103
and
101
are visible because the view axis is substantially perpendicular to the line formed by surfaces
101
and
103
, and is to the right of the plane formed by surface
102
, see
FIG. 2
, which is therefore not illustrated in FIG.
5
. Because of the angle at which the image is being viewed, or received by the viewing device, the lines
121
and
122
appear to be a single continuous straight line. Likewise, line pairs
122
and
123
, and
123
and
124
, coincide to give the impression that they are a single continuous lines. Because line
125
is projected upon a single level surface elevation, surface
104
, line
125
is a continuous single line.
When the pattern of
FIG. 5
is received by a processing device to perform a mapping function, the line pairs
121
and
122
,
122
and
123
, and
123
and
124
, will be improperly interpreted as single lines. As a result, the two-tiered object illustrated in
FIG. 2
may actually be mapped as a single level surface,
Rubbert Rudger
Sachdeva Rohit
Sporbert Peer
Weise Thomas
Johns Andrew W.
McDonnell & Boehnen Hulbert & Berghoff
Nakhjavan Shervin
OraMetrix Inc.
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