Digital Camera Patent AbstractThe invention relates to a digital camera, an imaging device and
a method for dental digital imaging. One sensor is used for tomographic
imaging and at least one sensor is used for transillumination imaging.
The sensors are arranged to overlap each other. This arrangement
provides a multiple use and a relative inexpensive camera compared
with the ones using one sensor with a large area. Additionally,
it is possible to arrange at least two separate electric connection
structures for the different imaging modes. Further, its connection
arrangements can be arranged in such a way that the mechanical connection
structures of the camera are separated from the electrical connection
structures.
Digital Camera Patent ClaimsThe invention claimed is:
1. A digital camera for dental imaging comprising: an image forming
surface; a first sensor module arranged on said image forming surface,
said first sensor module being structured and arranged for receiving
tomographic imaging information; a second sensor module arranged
on said image forming surface, said second sensor module being structured
and arranged for receiving transillumination imaging information;
wherein said first sensor module has a bottom edge and said second
sensor module has a top edge, said bottom edge of said first sensor
terminating vertically below the top edge of said second sensor
module.
2. The digital camera according to claim 1, further comprising:
means for forming an image information signal from said tomographic
imaging information received by said first sensor module.
3. The digital camera according to claim 1, further comprising:
means for forming an image information signal from said transillumination
imaging information received by said second sensor module.
4. The digital camera according to claim 1, further comprising
means for receiving the imaging information received by said first
sensor module and said second sensor module and forming a transillumination
image corresponding to an area covered by both of said first and
second sensor modules.
5. The digital camera according to claim 1, wherein each of said
first and second modules have a sensor surface and each of said
sensor surfaces are arranged on a y-z plane of a right angled x,
y, z coordinate system, said first and second sensor modules being
arranged such that a projection of the sensor surface of the first
sensor module taken along the x-y plane intersects with a projection
of the sensor surface of the second sensor module taken along the
x-y plane.
6. The digital camera according to claim 5, further comprising
a plurality of additional sensor modules, each one of said additional
sensor modules being arranged such that a projection of the sensor
surface taken along the x-y plane intersects with a projection taken
along the x-y plane of the sensor surface of a previous one of said
plurality of additional sensor modules.
7. The digital camera according to claim 5, wherein a peripheral
perimeter edge of an area defined by a projection of the sensor
surface of the first sensor module taken in the x, z plane is spaced
from a peripheral perimeter edge of an area defined by a projection
of the sensor surface of the second sensor module taken in the x,
z plane.
8. The digital camera according to claim 1, further comprising:
at least a third sensor module; wherein each of said first, second
and third modules have a sensor surface and each of said sensor
surfaces are arranged on a y-z plane of a right angled x, y, z coordinate
system, said first, second and third sensor modules being arranged
such that a projection of each sensor surfaces taken along the x-z
plane intersects with at least one other projection of the other
sensor surfaces taken along the x-z plane.
9. The digital camera according to claim 8, wherein at least two
of said first, second and third modules are arranged in a first
column in the x-y plane and the other one of said first, second
and third modules is arranged in a second column in the x-y plane.
10. The digital camera according to claim 1, wherein said first
and second sensor modules are substantially the same size.
11. The digital camera according to claim 1, wherein said first
module is arranged vertically above said second module.
12. The digital camera according to claim 1, further comprising:
means for operably connecting said camera to a display device.
13. The digital camera according to claim 12, wherein said means
for operably connecting said camera to said display device includes
a first signal path for transmitting image data to and from said
first sensor module and a second branched signal path for transmitting
image data to and from said first sensor module and to and from
said second sensor module.
14. The digital camera according to claim 12, wherein said branched
signal path includes means for combining partial images produced
by said first and second sensor modules to produce a transillumination
image.
15. The digital camera according to claim 12, wherein said means
for operably connecting said camera to said display device includes
separate means for mechanically connecting said camera to said display
device and means for electrically connecting said camera to said
display device.
16. The digital camera according to claim 15, wherein said means
for mechanically connecting said camera to said display device includes
means for positioning said camera.
17. The digital camera according to claim 12, means for operably
connecting said camera to a display device includes structurally
distinct first means for connecting said camera to said display
device for tomographic imaging and second means for connecting said
camera to said display device for transillumination imaging.
18. The digital camera according to claim 17, wherein said first
means for connecting said camera to said display device and said
second means for connecting said camera to said display device are
located on different physical surfaces of said camera.
19. An imaging device for dental imaging comprising: a radiation
source for producing a radiation beam; an imaging station; a collimator
structure for limiting the beam received from the radiation source;
means for mounting a camera; means for positioning the object to
be imaged; means for receiving image data from the camera comprising
a first sensor module arranged on an image forming surface, said
first sensor module being structured and arranged for receiving
tomographic imaging information and a second sensor module arranged
on said image forming surface, said second sensor module being structured
and arranged for receiving transillumination imaging information;
wherein said first sensor module has a bottom edge and said second
sensor module has a top edge, said bottom edge of said first sensor
terminating vertically below the top edge of said second sensor
module whereby portions of the first and second sensor are partially
overlapping.
20. The imaging device according to claim 19, further comprising:
means for forming an image information signal from said tomographic
imaging information received by said first sensor module.
21. The imaging device according to claim 19, further comprising:
means for receiving the imaging information received by said first
sensor module and said second sensor module and forming a transillumination
image corresponding to an area covered by both of said first and
second sensor modules.
22. The imaging device according to claim 19, wherein each of said
first and second modules have a sensor surface and each of said
sensor surfaces are arranged on a y-z plane of a right angled x,
y, z coordinate system, said first and second sensor modules being
arranged such that a projection of the sensor surface of the first
sensor module taken along the x-y plane intersects with a projection
of the sensor surface of the second sensor module taken along the
x-y plane.
23. The imaging device according to claim 19, wherein said first
module is arranged vertically above said second module.
24. The imaging device according to claim 19, wherein the collimator
structure is structured and arranged to enable the limitation of
the beam exclusively to the first sensor module during a tomographic
imaging.
25. The imaging device according to claim 19, further comprising:
means for taking a transillumination image by carrying out the scanning
movement of the beam by keeping the focus of the radiation source
steady and by moving the collimation arrangement limiting the beam
in a synchronized way with the movements of the camera.
26. The imaging device according to claim 19, wherein said imaging
station is a tomographic imaging station, said imaging device further
comprising: a transillumination imaging station; and wherein said
tomographic imaging station is arranged nearer to said radiation
source than said transillumination imaging station.
27. The imaging device according to claim 26, wherein said collimator
structure comprises a primary collimator structure located in the
vicinity of the radiation source and a secondary collimator structure
located at a distance from said radiation source in the vicinity
of said transillumination imaging station.
28. The imaging device according to claim 27, wherein said primary
collimator structure is structured and arranged to enable the limitation
of said radiation beam to essentially match the form and size of
said first sensor module, and said secondary collimator structure
is structured and arranged to enable the limitation of said radiation
beam to essentially match the overlapping portions of said first
and second sensor modules.
29. The imaging device according to claim 26, further comprising:
means for operably connecting said camera to said tomographic imaging
station. means for operably connecting said camera to said transillumination
imaging station.
30. The imaging device according to claim 29, wherein one of said
means for operably connecting said camera to said tomographic imaging
station and said means for operably connecting said camera to said
transillumination imaging station comprises separate electrical
and mechanical connection means.
31. The imaging device according to claim 30, wherein said separate
electrical and mechanical connection means are structured and arranged
such that said mechanical connection must be connected prior to
a connection of said electrical connection means.
32. The imaging device according to claim 30, wherein said mechanical
connection means comprises separate positioning means and means
for locking the connection means in a connected state.
33. The imaging device according to claim 30, wherein said camera
and said mechanical and electrical connection means are structured
and arranged such that during a mounting procedure of said camera
the camera must be mounted following a compulsory sequence in which
said mechanical connection is connected, said means for locking
the connection means is locked, and the said electrical connection
means is connected.
34. A method for dental digital imaging comprising the steps of:
arranging a radiation source to emit a radiation beam at an area
to be imaged; arranging a collimator structure to limit said radiation
beam; arranging a sensor assembly such that the same sensor assembly
is utilized for taking both tomographic images and transillumination
images, wherein said sensor assembly includes a first sensor module
structured and arranged for receiving tomographic imaging information
and a second sensor module structured and arranged for receiving
transillumination imaging information, and wherein said first sensor
module has a bottom edge and said second sensor module has a top
edge, said bottom edge of said first sensor terminating vertically
below the top edge of said second sensor module whereby portions
of the first and second sensor are partially overlapping.
35. The method according to claim 34, further comprising: forming
an image information signal exclusively from the information received
by said first sensor module.
36. The method according to claim 35, further comprising: removing
said information obtained from said second sensor module to thereby
form said image information signal exclusively containing information
received by said first sensor module.
37. The method according to claim 34, further comprising: combining
image information received from said first and second sensor modules
to form a transillumination image signal.
38. The method according to claim 37, further comprising: reading
image information from different stages of a scanning movement receiving
by said first and second sensor modules and then combining said
information received from said first and second sensor modules to
form said transillumination signal; and removing any duplicate information
obtained from both said first and second sensor modules from said
transillumination signal to thereby from a complete transillumination
image.
39. The method according to claim 37, further comprising: limiting
said beam by said collimator structure before said area to be imaged
such that a projection of said beam on said area to be imaged is
substantially equal in size to a projection of said first and second
modules on said area to be imaged.
40. The method according to claim 34, further comprising: providing
means for operably connecting said camera to said display device
including a first signal path for transmitting image data to and
from said first sensor module and a second branched signal path
for transmitting image data to and from said first sensor module
and to and from said second sensor module.
41. The method according to claim 34, wherein each of said first
and second modules have a sensor surface and each of said sensor
surfaces are arranged on a y-z plane of a right angled x, y, z coordinate
system, said first and second sensor modules being arranged such
that a projection of the sensor surface of the first sensor module
taken along the x-y plane intersects with a projection of the sensor
surface of the second sensor module taken along the x-y plane.
42. The method according to claim 34, wherein said first module
is arranged vertically above said second module.
43. The method according to claim 34, further comprising: limiting
said radiation beam to match said first module during a tomographic
imaging and limiting said radiation beam to match said first and
second modules.
44. The method according to claim 34, further comprising: conducting
a transillumination scan by maintaining said radiation beam and
an object to be scanned stationary; and moving said collimator structure
and the sensor assembly in a synchronized manner. Digital Camera Patent DescriptionThis invention relates to a digital camera according to the preamble
of claim 1, to an imaging device according to the preamble of claim
23, and to a method according to the preamble of claim 38 for digital
imaging.
In particular, one of the objectives of the invention relates to
dental panoramic and other tomographic imaging, and to a digital
camera and imaging device used in cephalometric imaging, in which
the area covered by means for receiving the image information is
essentially smaller than the projection of the object to be imaged
on the image-forming surface. In this context, the image-forming
surface denotes the virtual plane or surface on which the projection
of the object to be imaged is formed.
Further, the invention relates to a method for digital imaging
in which method the object to be imaged is radiated and the radiation
is detected by means for receiving the image information, the area
covered by which being essentially smaller than the projection of
the object to be imaged on the image-forming surface.
Various tomographic and transillumination imaging methods are used
in many kinds of applications. Among others, in the medical and
biotechnological imaging applications, it is typical to direct x-ray,
gamma, or beta radiation through the object to be imaged and further
to the image-forming surface. Digital imaging methods have been
developed at the side of the traditional film-based imaging methods,
and in these methods semiconductor sensors, such as CDD sensors
(Charge-Coupled Device) or CMOS sensors (Complementary Metal-Oxide
Semiconductor) are used as image-forming surfaces. Typically, in
such semiconductor sensors, x-rays are first converted to radiation
the wave-length of which is in the region of visible light but the
developing technology is also introducing sensors in which x-rays
can be directly converted to electric form.
Despite the many advantages offered by the digital imaging devices,
they have not become as generalised as expected in so many visions.
The prices of digital cameras have been one of the essential factors
having had influence on this. The semiconductor sensors used in
the cameras are typically made of silicon and, along with the growth
of the size of the sensor, its manufacturing costs per surface area
grow exponentially. This is why, in the applications requiring a
wide imaging surface, cameras comprising of one semiconductor sensor
will become very expensive.
The invention presented in this application has been developed
in view of the needs of dental x-ray imaging, and thus, it will
be illustrated below primarily in the light of the applications
of this field. Naturally, the invention is also suitable for use
in connection with many other imaging forms.
The dental x-ray imaging is divided in three main sections, out
of which in the so-called intraoral imaging it is typical to image
individual, or a few teeth, in the so-called panoramic imaging the
dental arch is imaged to a plane as a layer, i.e. as a tomographic
image, and in the so-called skull or cephalometric imaging the skull
area as a whole is imaged as a transillumination image. Further,
many devices used for panoramic imaging are suitable for taking
even other cross sectional images of various areas of the dental
arch. The present invention is particularly suitable for use in
connection with the panoramic and other tomographic imaging forms
and with the skull imaging, all of which being typically made by
the same imaging device. Particularly in the cephalometric imaging,
the need for image information receiving means with large surface
area has appeared problematic from the point-of-view of the commercialisation
of the digital imaging applications. Taking a skull image with a
sensor having a directly matching size with the area to be imaged
would require use of tens of times bigger sensors as typically used
in panoramic imaging.
As the dental skull image is a transillumination image it is traditionally
taken by using so wide a beam and film that the desired area has
been able to be imaged as one single shot. On the other hand, in
panoramic imaging a tomographic image is typically produced by using
a narrow beam and the area to be imaged is scanned by it, whereby
the tomographic effect for imaging the desired anatomic layer is
created by continuously changing the entry angle of the beam in
relation to the object as the beam travels over the area to be imaged.
In this so-called narrow beam tomography method, the movement of
the imaging means (the radiation source and the image information
receiver) is implemented in a controlled way so that the receiver
is moving in relation to the beam with a transversal speed corresponding
the vertical scanning speed of the beam in the area to be imaged,
multiplied with a magnifying factor, i.e. a coefficient that is
the relation between the distance from the image information receiver
of the focus of the beam (=radiation source) and the distance from
the area to be imaged. In this definition, the detector primarily
refers to the radiographic film, whereby, in the digital imaging,
the movement of the image information receiver in relation to the
anatomic layer to be imaged can be replaced by a suitable electric
function, as a charge transfer on the surface of the semiconductor
sensor. Mathematically, this imaging equation can be presented in
the following form: V.sub.F=(L.sub.FF/L.sub.OF).times.V.sub.O where
V.sub.F=speed of film transfer, or an electric function by the sensor
corresponding to it, L.sub.FF=distance of film or any respective
element from the focus of the radiation source, L.sub.OF=distance
of the object to be imaged from the focus of the radiation source
and V.sub.O=forward speed, parallel to the image-forming surface,
of the beam in the object. Therefore, the precondition to a successful
panoramic imaging is that, during the imaging, the respective positions
of the means to receive the image information, of the area to be
imaged, and the radiation source in relation to each other, continuously
remain, as precisely as possible, in compliance with this theoretical
imaging equation.
In the digital panoramic imaging, the scanning movement of the
beam is followed by a narrow sensor from which the image data is
read out during the scan. As the panoramic and cephalometric images
have typically been taken by the same x-ray imaging device, it has
been a natural idea to use the so-called scanning slot imaging technology
also for taking the transillumination images of the skull area (e.g.
"Direct digital extraoral radiology of the head and neck with
a solid-state linear radiographic detector", McDavid, W. D.
et al., Oral Surg Med Oral Pathol 1992; 74:811 7). This is how the
sensor surface area needed for imaging has been able to get considerably
reduced. In some of such applications, however, the scan has been
implemented in a way causing at least theoretical errors in the
image, i.e. as the beam is positioned to meet the image information
receiver perpendicularly and the scanning of the object is carried
out by either conveying the object perpendicularly through the beam,
or by positioning the object in a fixed position and by moving the
radiation source and the image information receiver with a parallel
synchronized movement past the object. These kinds of imaging modes
do not produce genuine transillumination images but, as a matter
of fact, tomographic images where the size of the tomographic effect
depends on the width of the beam used. In addition to this, interpreting
of the images obtained in this way is not familiar to the doctors,
as their projection geometry is different in the horizontal and
vertical directions, thus deviating from the traditional geometry
of a transillumination x-ray image.
From the point-of-view of practical applications, use of the same
sensor both in the cephalometric and panoramic imagings would be
desirable, among others regarding the administration of the camera
production and the sensor storage solutions, as the costs of starting
the production and, as the manufactured numbers would get larger,
the costs per unit, could thus be reduced. In digital panoramic
imaging the height of a typically used sensor is, regarding the
cephalometric imaging, however, sufficient only in a few special
applications, which is why two different sensors have to be manufactured
for the market. Therefore, the scanning slot imaging as such does
not provide a solution based on which one could manage with only
one single sensor.
A feasible possibility as such would be to use a cephalometric
imaging sensor in panoramic imaging in such a way that the sensor
height would be utilized only partly, but even this solution is
problematic from the commercial point-of-view. The sensor that is
sufficiently high for cephalometric imaging is more expensive than
two panoramic sensors, i.e., with today's prices, the camera needed
for cephalometric imaging might cost even more than the rest of
the imaging equipment altogether. As typically only about one third
of the panoramic devices are provided with means for cephalometric
imaging, regarding this and the points presented above, it is very
understandable that the digital cephalometric imaging applications
have not become significantly more general.
Use of the same digital camera for panoramic and cephalometric
imagings has been considered e.g. in the U.S. Pat. No. 5,579,366.
This publication primarily discusses one dimensional digital cameras,
to the evident idea of using a sensor that is high enough even for
cephalometric imaging applications, i.e. a camera that is expensive
and overdimensioned from the point-of-view of the needs of mere
panoramic imaging. In the scanning cephalometric imaging, a longer
sensor than in the panoramic imaging is needed, in any case, whether
the imaging scan is made horizontally or vertically.
The actual invention according to the said U.S. Patent Publication
concerns the camera interface arrangements that seem to be easy
to use as such but that also include potential sources for problems.
Use of the same camera in different imaging positions requires its
repeated transfer between the panoramic and the cephalometric imaging
stations and these measures will always imply a risk of damaging
the expensive camera, e.g. as a consequence of dropping it. Often
repeated removals and attachments set requirements of their own
also to the mechanical, and particularly to the electric interface
solutions of the camera. In practice, the problem of the interface
solution according to the the publication might prove to be the
precise and steady positioning of the camera in the imaging device,
which is critical, in particular, in scanning slot imaging.
Also in connection with other imaging applications, different solutions
have been developed to solve the surface area/price problem of the
semiconductor sensors. Typically in these solutions, sensors covering
only a part of the image-forming surface are used, which are then
moved or transferred during the exposure, or between, individual
exposures. E.g. in the mammographic devices different mosaic or
chessboard pattern built sensors have been used, which are then
moved between two or several different exposures. Typically, the
different modular realisations are expensive and to make them function
in practice, too, the combination of the modules has to be carried
out with extreme precision--especially when the intention by combining
them is to construct a uniform sensor surface based on modules.
The Patent Publication WO 95/12133 presents a modular sensor arrangement,
based on the formation of a kind of zig-zag pattern, to be used
in different radiographic and tomographic imaging applications.
This as such technically excellent solution has not, however, been
shown to become a commercial success, at least not in connection
with medical imaging--probably at least partly due to the fact that,
e.g. a uniform panoramic image cannot be achieved by this kind of
a sensor. In the sensor arrangement according to the Publication,
the sensor modules are all the time moving, in the direction of
the scanning movement, in different stages, i.e. in relation to
the rotational centre they are in each moment of time in different
positions and are continuously imaging the object from different
projections, i.e. they form images based on different imaging geometries.
Therefore, such a sensor arrangement creates an image formed of
stripes of the different projections, parallel with the scanning
movement, where on the borders of them there may be points of incontinuency.
In particular, in the (dental) medical radiographic imaging, these
kinds of faults in images are not acceptable.
Therefore, the objective of this invention is to develop digital
imaging technology to reduce the problems presented above. In particular,
the objective is to develop a camera that is relatively inexpensive
to manufacture and to acquire, suitable for scanning slot imaging,
an imaging device for the use of this kind of camera, and an imaging
method based on a corresponding technology. In this way, the investments
to digital technology, become more justifiable and the threshold
for its introduction lower. The digital technology, among other,
will make the doctor's work easier as it enables getting images
of better quality, and thus more precise diagnoses, but even saving
the pictures and administration of them in electric form--together
with the rest of the documentation concerning the patients and the
adminstration of the reception.
One of the objectives of the invention is to provide such a camera
that it can be used in more than one form of imaging, particularly
in both tomographic and transillumination imagings, especially in
the same imaging device, and possibly in its different imaging positions.
Further, the objective of the invention also is to provide such
a method for digital imaging according to which the same camera
can be used to take both tomographic images and transillumination
images--even of objects of different sizes.
Further, one of the objectives of the invention is to provide a
camera the sensor surface of which could simply and with moderate
cost be modified, implying that one of the objectives of the invention
is to provide this kind of a camera using a modular sensor arrangement.
One of the additional objectives of the invention is to provide
a modular sensor arrangement for the camera in such a way that the
characteristics of the camera can be easily changed, without the
need to change its basic structure, when one further additional
objective of the invention is to provide the modular sensor arrangement
for the camera so that it will be easy to add modules to the camera
in order to increase the sensor surface of the camera, or so that
the way it is used can be altered so that different imaging modes
and imaging of objects of different sizes will be possible with
the same camera.
A particular objective of the invention is to provide such a camera
suitable for dental panoramic and other tomographic imaging, that
can be used, or that can be relatively easily and economically be
modified so that it will also be suitable for dental cephalometric
imaging.
Further, one of the objectives of the invention is to provide a
modular sensor arrangement for the camera so that the camera can
be used utilizing only a part of it, especially in tomographic imaging
utilizing only one module, that of the sensor arrangement.
One of the additional objectives of the invention also is to implement
the sensor arrangement so that the possibly broken individual sensor
module could easily be replaceable by a new one, possibly by a module
that is identical with the other modules.
A further additional objective of the invention is to provide such
a modular sensor system for the camera that the sensor surfaces
of the modules and/or the circuit boards belonging to the modules
can be positioned also on different levels.
One of the special objectives of the invention is to provide an
imaging device in which the same camera according to invention can
be used for both tomographic and transillumination imaging, in particular,
for both dental panoramic and cephalometric imaging.
Further, one of the additional objectives of the invention is to
provide such an imaging device whereby a camera according to the
invention can easily and safely be moved from one imaging station
to another and positioned precisely in its correct imaging position.
Further, one of the additional objectives of the invention is to
implement the camera connection arrangement so that it will consist
of at least two structurally different connectors, to connect the
camera correctly to its imaging stations for at least two different
imaging purposes.
Further, one of the additional objectives of the invention is to
provide such an imaging device in the imaging positions of which,
designed for at least two different imaging purposes, there are
structurally different connecting arrangements for connecting the
camera to the imaging device.
Further, one of the additional objectives of the invention is to
utilize the connection arrangements of the camera to direct the
image information received from certain modules of the camera out
from the camera via signal paths exclusively assigned to these modules--in
particular, to direct the image information from one module for
tomographic imaging out from the camera via a connection arrangement
exclusively suitable for a tomographic imaging station.
One of the additional objectives of the invention is to realize
the usability of the camera in more than one point of use so that
the removal and connection of it would include as few risks as possible
for damaging the camera itself, as well as its connecting structures.
Further, one of the additional objectives of the invention is to
realize the connecting arrangement of the camera so that its electric
connecting parts would be as little vulnerable as possible to mechanical
stress that might, in time, damage them and lead to intermittent
power contact failures, or even to a permanent failure.
Further, one of the additional objectives of the invention is to
realize the connection arrangement of the camera so that it can
be positioned to its imaging station relatively simply but in the
same time as precisely and for being as non-movable as possible.
Further, one of the additional objectives of the invention is to
realize the connection arrangement of the camera so that it will
ensure a stable and safe mounting of it in the imaging device, in
order to minimize the electrical safety risks that could be caused
by e.g. unusually strong external forces upon the camera. These
forces can be caused by e.g. stumbling on the camera so that the
connection structures would bend and cause shortcuts and thus potential
damages to the imaging device and the camera, or even personal injuries
as a consequence of an electric shock.
Further, one of the additional objectives of the invention is to
provide such an imaging device where the connection arrangements
intended for the camera have been realized by using separate mechanical
and electric connection structures.
Further, one of the additional objectives of the invention is to
realize the connection arrangement so that its mechanical and electric
connection structures have been separated from each other, e.g.
placed physically on different surfaces of the camera housing.
Further, one of the additional objectives of the invention is to
realize the connection arrangement so that fixing of the camera
will take place in a compulsory sequence of--positioning--locking
of the mechanical connection--electric coupling.
The essential characteristics of the invention have been presented
in detail in the attached claims. One of the main characteristics
of these is a modular sensor arrangement of a digital camera that
consists of, in view of sensor surfaces or their projections on
a certain plane, in particular, the point projections in relation
to the focus of the radiation source, an overlapping assembly formed
by at least two sensor modules--or of a structure including at least
the first module, and with means arranged for connecting at least
another module functionally to the structure to provide this kind
of an assembly; whereby the first module has been arranged to be
used for scanning tomographic imaging, and whereby this said module
has been arranged to be available for scanning transillumination
imaging together with at least another sensor module. In the same
way, in the method according to these characteristics, particularly
one module unit of the modular sensor assembly is used for tomographic
imaging, whereby this same module, together with at least another
module belonging to this sensor assembly, is also used for transillumination
imaging, whereby imaging of even larger areas than the areas that
can be imaged by this first module will become possible.
In particular, the overlapping module assembly according to this
invention means a sensor arrangement whereby the sensor modules
have been positioned, in relation to each other, in an overlapping
position so that
considering the sensor surfaces of the sensor modules, or their
projections on the plane formed by the axles y, z of a right-angled
set of coordinates x, y, z,
whereby a projection here indicates, in particular, the point projection
which is imaged to said plane via the focus of the radiation source
used in the imaging and the said sensor surface,
each of them covers a different area on this plane, and that,
when proceeding in the direction of the axle y,
the projection, or the said point projection of the sensor surface,
of each subsequent sensor surface placed on the plane formed by
the axles x, z, will cover a different area from the previous projection,
and that the projection, or the said point projection of the sensor
surface, of each subsequent sensor surface placed on the plane formed
by the axles x, y, will meet that of the previous projection--possibly
by at least partially covering the same area.
The modular structure according to this definition can therefore
be implemented so that, when proceeding in the direction of the
axle y, each subsequent projection, on the plane formed by the axles
x, z, covers a different area from the previous projection so that
the borders of these areas meet.
When the camera with the sensor arrangement according to the invention
is positioned in the imaging device using scanning slot technology
according to this invention, the direction of the scanning movement
of the beam is the direction of the axle z of the definition above.
Thus, the sensor assembly can consist of only the first sensor
module used for tomographic imaging and, in addition to this, the
means, such as the space required and the means attached to it for
connecting at least one another sensor module functionally to this
arrangement, in order to form an overlapping modular structure.
In the following, the invention will be described in more detail,
using its preferred embodiments and referring to the attached figures,
out of which
FIG. 1 shows a typical traditional panoramic and cephalometric
imaging device,
FIG. 2 shows a structure of a camera housings according to the
invention,
FIGS. 3A 3E show some sensor module arrangements according to the
invention,
FIG. 4 shows a collimator system according to one preferred embodiment
of the invention used to limit the beam of an imaging device,
FIGS. 5A and 5B show one way according to one preferred embodiment
according to this invention to connect the camera to the panoramic
and cephalometric imaging device, and
FIG. 6 shows a camera holder-connector structure in an imaging
device according to one preferred embodiment according to this invention.
FIG. 1 shows one typical, traditional film-based panoramic and
cephalometric imaging device comprising a body part 1, another body
part 2 movably attached to it, with further a suspension arm 3 movably
attached to the second body part 2, at the essentially opposite
ends of which the radiation source 4 and the image information receiver
5 used in panoramic imaging are located. In the device according
to FIG. 1, this image information receiver 5 is a film cassette,
but it could also, respectively, be a digital camera attached to
the suspension arm 3. In addition, positioning means for the object
to be imaged are also typically used in panoramic imaging; their
position in FIG. 1 is referred to by reference number 6. To control
the functions of the device, it also typically comprises a user
interface 7.
To the device according to FIG. 1 are attached means for taking
cephalometric images, when it also comprises another suspension
arm 8 with positioning means 9 for the object to be imaged in cephalometric
imaging attached to it, as well as means 10 for positioning and
attaching the image information receiver, which in the device according
to FIG. 1 is a film cassette.
In addition, considering the digital application of this kind of
device, a panoramic 11 and respectively a cephalometric 12 imaging
station of the camera 5 have been indicated by reference numbers
11 and 12 in FIG. 1. These imaging stations will be later referred
to in connection with the embodiments of the invention according
to FIGS. 5 and 6.
When using the imaging device shown in FIG. 1, the object to be
imaged is positioned either in a desired tomographic imaging position,
in the area indicated by reference number 6, between the radiation
source 4 and the image information receiver 5, or in a desired cephalometric
imaging position, by the positioning means 9 used in the cephalometric
imaging. In tomographic imaging, a layer of the desired anatomy
is imaged by moving the radiation source 4 and the image information
receiver 5 in a controlled way on the essentially opposite sides
of the object to be imaged so that at the same time the area to
be imaged is scanned by a narrow beam. On the other hand, for cephalometric
imaging, the radiation source 4 is positioned to direct the beam
towards the positioning means 9 used in cephalometric imaging, and
further towards the image information receiver not shown in FIG.
1. The traditional film-based devices have typically had to be constructed
so that the structures that remain between the radiation source
4 and the cephalometric imaging station 12, as the holder structures
of the panoramic film cassette 5, or the like, have had to be moved
aside when the device has been changed from panoramic imaging mode
to cephalometric imaging mode. In particular, in applications using
the same digital camera 5 this problem can simply be solved by producing
such a panoramic imaging station 11 of the camera 5 that removal
of the camera 5 is sufficient to leave a free path for the beam
towards the camera 5 moved to its cephalometric imaging station
12.
FIG. 2 shows a structure of a camera housings 51 of a digital camera
5 according to the invention. In this embodiment of the invention,
respective apertures 53, 53' matching the form of one of the sensor
module arrangements according to the invention have been arranged
to the actual housing part of the camera 5, which is covered by
an upholstery surface which is permeable to the radiation used for
imaging. In addition, camera 5 comprises means 60 for positioning
and mechanical fixing of the camera 5, to be later shown in more
detail in connection with FIG. 6, and means 70 for electric connection
of the camera, which means can be implemented so that there are
separate connecting means in the camera, on one hand for different
imaging modes, and on the other for electrical and mechanical connections
of the camera to the imaging device.
FIGS. 3A 3E show some of the sensor module arrangements according
to the invention. In this context, by sensor module is meant any
structure forming an essentially uniform sensor surface. The sensor
module 20 may e.g. have the structure shown in FIG. 3A, of the sensor
structure 21 formed by four CCD microchips, optical fibre 22, scintillating
material 23, housing 24 of the sensor structure 21, cover 25 and
a printed circuit board (PCB) 27, or the like, coupled to this structure
by electric interface surfaces 26, but it may also consist of, e.g.,
a single monolithic CCD chip.
The sensor module arrangement according to the invention may be
implemented in innumerable different ways out of which some have
been shown in FIGS. 3B 3E. These figures show the structure of camera
5 seen from the direction of the focus of the radiation source,
when the radiation containing image information is directed via
the apertures 53, 53' of the camera housing 52, essentially corresponding
to the form of the sensor module arrangement of camera 5, to the
sensor modules 20, 20', 20'', 20''' that have been placed on the
opposite inner wall in relation to the apertures 53, 53'0 of the
camera housing. A right-angled set of coordinates x, y, z according
to the definition used above has been added to the FIGS. 3B 3E,
where the direction of the axle z is the same as the direction of
the movement of the camera, i.e. the scanning direction of the beam,
when the camera is used for scanning slot imaging.
FIG. 3B shows the simplest embodiment, consisting of two modules
20, 20', of the sensor module arrangement according to the invention.
With a camera 5 consisting of this kind of a structure one is able
to take a tomographic image using one module 20, and a larger transillumination
image by using also the other sensor module 20' positioned in overlapping
relation to the first module 20. The stripe-forming effect encountered
in tomographic imaging, where at any moment of time during the imaging
scan the sensors are at different stages, can be controlled without
problems in transillumination imaging. When the focus of the radiation
source and the object to be imaged are held stationary and the scanning
movement of the beam is implemented by collimators limiting the
beam, the modules moving synchronized with the scanning movement
form a true transillumination image, each of them at a certain stage
of the scanning movement, i.e. e.g. when using the sensor arrangement
according to FIG. 3B, when the modules pass the object from left
to right, the upper part of the transillumination image will be
completed later than the lower one. Even a long distance between
the modules 20, 20' in the direction of scanning movement is not
problematic from the point-of-view of the formation of the final
integrated image but, naturally, e.g. due to the possibly uneven
radiation output of the radiation source 4, or regarding the physical
dimensions of the camera, this distance should, however, be left
as short as will be reasonable, regarding the other solutions of
the camera arrangement. And, as in all slot imaging applications
of this type, it would also be preferred, in view of the object
not to move, to be able to have as short imaging time as possible,
i.e. to keep the distance in between the modules scanning direction
as short as possible for this reason, too.
If the projections of modules 20, 20', on the plane formed by axles
x, y at least partly cover the same area this will not cause any
problems in the formation of a transillumination image, as the overlapping
parts can be integrated by the image processing methods evident
to those professed in the art, to appear as if they had been taken
by one sensor. The partial images can be combined e.g. so that the
image information corresponding to the part of the object that has
possibly been imaged more than once, due to the overlapping of the
sensor surfaces, is either removed from the information produced
by all the modules except one, or, in particular, so that all of
the information received is used in forming the image and the part
having been imaged more than once is scaled to correspond the image
information that would have been received from only one sensor module.
On the other hand, overlapping is also useful regarding the fact
that then there will certainly not be left any gaps between the
partial images formed by the separate modules. In some special imaging
modes it may even be appropriate to arrange two ore more modules
to image, even totally, the same area, i.e. to arrange the modules
so that, according to the definition used above, the projections
of the sensors cover the same areas on the plane formed by the axles
x, y.
According to the invention, the camera 5 may also include three,
four, or even more sensor modules to form e.g. an over-lapping line
according to FIG. 3C, a structure formed by sensor modules of different
sizes according to FIG. 3D, or a structure formed by two columns
according to FIG. 3E. Then, FIGS. 3D and 3E illustrate the possibility
that, according to the definition used above, when proceeding in
the direction of the axle y, the border of the area covered by each
successive projection on the plane formed by the axles x, z can
be at a distance in different directions from the border of the
area covered by the previous projection, compared with the previous
projection and the one before it, and that these projections may
cover, partly or even totally, the same area. This kind of covering
the same area cannot, however, be present when proceeding in the
direction of the axle y for any two successive projections.
FIGS. 3B to 3E only show some simple basic structures that cap
be combined and extended in many different ways within the basic
idea of the invention. Further, according to the invention, the
sensor module arrangement can also be realized e.g. by arranging
the modules 20, 20', 20'', 20''', and, in particular, their surfaces
23 receiving the image information, on different planes, i.e. at
different distances from the focus of the radiation source. This
can be realized e.g. by using connecting surfaces 26 of different
lengths. On the other hand, using connecting surfaces of different
lengths, it is possible to create a structure where the sensor surfaces
are at the same level but where the printed circuit boards 27, or
the like, are at different levels. These types of arrangements allow
more latitude for the implemention of the electronics arrangements
of the camera. The marginal magnification error caused by the position
of the sensor surfaces at different distances from the objects to
be imaged can, if desired, be corrected e.g. by the image processing
methods known as such.
In order to achieve as effective sensor surface as possible in
transillumination imaging using the sensor module arrangement according
to the invention, it would be preferred to leave the possible overlapping
portion of the sensor surfaces, naturally even for cost reasons,
as short as possible. In principle, the sensor module arrangement
could be realized so that, according to the definition used above,
the projections of the sensor surfaces on the plane formed by the
axles x, y, would not overlap at all, i.e. that the distance between
them would be zero. A so precise physical positioning of the modules
is, however, technically more difficult to achieve than e.g. an
arrangement where the modules are positioned at least a little overlapping
and the possible extra overlapping will be taken into account in
the imaging process, e.g. by using a suitable collimation of the
beam. Furthermore, an overlapping of the size of at least one row
of sensor pixels is preferred also because the combination of images
is then more easily feasible, using means offered by many as such
known electronic and/or image processing software solutions. Especially
if the effective height of the sensor arrangement does not belong
to the critical development criteria, the use of overlapping and
its optimal magnitude can be considered in the light of any particular
characteristics of the respective application.
Regarding the needs of dental imaging, it is preferred to arrange
the module used for tomographic imaging as the lowest module of
the sensor module arrangement, as in all other cases especially
the imaging of the lower jaw onto the panoramic image is difficult
to arrange. In these type of applications, it is also preferred
to implement the sensor module arrangement according to the invention
so that two identical modules, possibly in overlapping positions,
are used, and the physical and electronic arrangements of the camera
are implemented so that the modules can be easily removed and/or
connected to the camera. Expressed more precisely, this means that
it will be possible, in the first stage, to arrange in the camera
housing only the module needed for tomographic imaging, and the
physical space needed for the transilllumination imaging module
plus the necessary means for its positioning and functional connection
to the camera. In this way, a panoramic camera is provided with
a relatively inexpensive acquisition price, and to which, however,
another module needed for cephalometric imaging can later be connected
in a simple way. In addition to this, thus a damaged module can
easily be replaced by a new one and if the damaged module happened
to be one used only for cephalometric imaging, the camera can still
be used for panoramic imaging purposes even during the time the
acquisition of a new module takes. The price of this type of a panoramic
camera can be made to match the price of a conventional panoramic
camera, i.e. the camera will be significantly cheaper--due to its
smaller sensor surface--than a panoramic camera consisting of one
sensor module that could as such also be used for cephalometric
imaging. In addition, even price of a camera according to this invention,
extended suitable also for cephalometric imaging, consisting of
two relatively small sensor modules will, however, remain clearly
lower than that of a one module camera of comparable size. Even
in a more general consideration, a sensor arrangement according
to the invention can thus be realized so that, for whatever single
module or several modules used only for transillumination imaging,
only the physical space and the necessary means for connecting the
module functionally to the camera are arranged to the camera housing,
in which case the sensor arrangement can by simple connection measures
be arranged to form a larger overlapping modular structure.
According to the invention, there are numerous ways to remove or
discard the signal produced by other modules than that used for
tomographic imaging from the image information used for creating
the tomographic image. E.g. the electronics arrangements of the
camera can be implemented so that the signal path to the transillumination
imaging modules can be cut, or so that the image is formed, or the
image data is transmitted from the camera to separate image processing
means only from the signal received from the tomographic imaging
sensor. The non-desired information can be sorted out and removed
by using electronics arrangements, known as such, e.g. in the logic
circuit of the camera, or later by image processing methods, known
as such. In addition or besides to these arrangements, it is also
possible to proceed so that the collimation arrangement limiting
the beam of the imaging device is implemented so that, when the
imaging device is used for tomographic imaging, the access of radiation
to other sensor modules is blocked.
Further, taking into consideration certain preferred embodiments
to be presented later, one possible solution is to arrange two sets
of separate electric connection means for the camera, in which case
the signal paths can be arranged so that one connecting element
will be in connection only to the tomographic imaging sensor module
and the other both to the tomographic imaging sensor module and
at least to one transilluminaton imaging sensor module--or then
at least to one of the connection means arranged for this type of
module. Thus, when the first mentioned electric connector is used
for attaching the camera to the tomographic imaging position, automatically,
only the image information produced by the tomographic image sensor
module is obtained via this connector, as desired.
The final formation of the image may be done in ways known as such,
e.g. by connecting the imaging device to a computer, whereby the
memory and the processing means of the computer can be utilized.
The processing means can also be realized by e.g. a dedicated ASIC
circuit (Application Specific Integrated Circuit), connected to
memory means, e.g. RAM memory. Naturally, and as already partially
described above, many measures of the image information processing
can already be carried out in the camera, e.g. specifically in the
ASIC circuit arranged to the camera. The formation of the final
image information as such is well-known technology to those professed
in the art, and a more detailed description of it is not necessary
for the implementation of the invention. In principle, the camera
may be made by arranging all means required for the image formation
in the camera itself when it could be connected directly to the
display device.
In the implementation of the invention, it is possible to utilize
the CCD sensor technology known as such, having shown to be very
useful in e.g. panoramic imaging. On the other hand, one interesting
alternative also is the use of a newer technology based on CMOS
sensors and direct detection of radiation, as with them certain
advantages can be obtained as compared to the traditional semiconductor
sensors. The CMOS sensor technology as such enables, due to its
so-called parallel bus type data transfer system, a faster transfer
of image information, and with sensors based on direct detection
an even better resolution is achieved than with the traditional
semiconductor sensors, when there are no scintillating and optical
fibre structures reflecting light also to non-desired directions.
The sensitivity of the sensors based on direct detection is better,
too. The CMOS technology is the most commonly applied semiconductor
technology and, because of this, the availability of CMOS circuits
is good and their manufacturing costs are being reduced by the technical
development.
One of the sensor technologies based on direct detection of radiation
has been described in more detail e.g. in the Patent Application
Publications WO 95/33332 and WO 97/20342. It is not possible to
perform a charge transfer function (Time Delay Integration=TDI)
with this type of a sensor, nor is there any simple way to construct
such a function to it. However, this type of a sensor can be used
in these imaging modes by forming the image so that an image of
the object is produced every time the object to be imaged, or the
sensor, has moved about one pixel forward, and by adding these images
to each other so that they are, at the same time, overlapping a
corresponding distance in relation with each other.
FIG. 4 shows one preferred embodiment of the invention for a collimator
arrangement for limiting the beam, which in the situation shown
in the figure has been arranged to be ready for use in cephalometric
imaging. In cephalometric imaging the beam received from the radiation
source 4 is first limited by a primary collimator 31 (collimator
opening 31A) placed in the vicinity of the radiation source 4, and
before the object to be imaged 33 by another collimator 32 placed
to a sufficient distance from the focus, which will limit the beam
to essentially match the form of the areas 53, 53' the camera housing,
which are permeable to radiation. The scanning movement of the beam
is realized by the movement of the collimators and the camera is
moved synchronized with this movement. If the sizes of the active
surfaces 23, 23' of the sensor modules 21 and of the areas 53, 53'
permeable to radiation, especially their overlapping, are arranged
to be larger than the effective sensor surface 23, 23' required
in the respective imaging, with a suitable limitation of the beam
it will be possible to prevent the unnecessary direction of radiation
through the object to be imaged 33 twice, to the area of the sensor
surface not to be utilized in image formation, and the image information
of the area left outside the beam can be removed before the partial
images are combined.
Panoramic imaging can be realized in a manner known as such by
the structure according to FIG. 4 by positioning the aperture 31B,
intended for panoramic imaging, of the primary collimator 31 in
the essential vicinity of the radiation source 4 to limit the beam
to match the conventional beam used in panoramic imaging, i.e. to
essentially match the aperture 53 of the camera housing.
The FIGS. 5A and 5B show one of the preferred ways to attach the
camera 5 according to the invention to the imaging device. In the
solution according the figures, the camera 5 can be considered as
positioned e.g. to its cephalometric imaging station 12 in FIG.
5A and to its panoramic imaging station 11 in FIG. 5B. In FIGS.
5A and 5B arrow 41 indicates the entry direction of the x-rays to
the camera 5, i.e. the camera 5 and the connection arrangements
42A, 42B of the imaging device have been arranged to be of different
structure, so that the camera 5 can, on one hand, only be mounted
from one direction to the cephalometric imaging station 12, and
from the other direction to the panoramic imaging station 11 (compare
with FIG. 1). When the said directions have been arranged horizontally
according to FIGS. 5A and 5B, moving the camera 5 between the imaging
stations 40A, 40B is easy and fast, and at the same time, the danger
of dropping the camera 5 unintentionally has been minimized. When
positioning oneself to the area between the panoramic imaging station
11 and the cephalometric imaging station 11, 12, the camera is easily
removable from one imaging station and attachable to the other imaging
station by using a simple horizontal movement. In this way, that
critical time for the risk of damaging the camera 5 when it is not
safely mounted and secured to the imaging device, is reduced.
Technically, the imaging device according to the invention is,
naturally, also possible to realize so that the scanning movement
of the beam is made in some other direction than horizontally. Especially,
the panoramic and cephalometric imaging devices according to the
invention can be made so that the scanning movement of the cephalometric
imaging is arranged to be done in vertical direction, whereby the
sensor module arrangement can be implemented in a somewhat shorter
form.
FIG. 6 shows a connection arrangement 60', 70' enabling one preferred
embodiment of the invention shown in FIG. 5 to fix the camera 5
according to FIG. 2 to the imaging device. The structure shown in
FIG. 6 may be considered to correspond the panoramic imaging station
11 according to FIG. 5B, when e.g. the respective connecting arrangement
(60, 70) forming a structural mirror image may be arranged to the
cephalometric imaging station 12. The connection arrangement 42B
according to FIG. 6 consists means 60' for positioning and mechanical
mounting of the camera 5 and means associated with the electrical
coupling 70' of the camera. The camera 5 is brought to the imaging
station 11 in the direction of the guiding rails 61, 62 that ensure
the correct positioning, from the opposite side of their end plate
63. When the guiding rails 61, 62 have penetrated fully into the
matching guiding grooves in the camera 5, the fixing of the camera
5 can be secured by turning the locking means 64 to its locking
position over the camera housing 51. Additionally, the connection
arrangement according to FIG. 6 can also be made so that the electric
connecting means 71, 72 are moved to contact the matching elements
in the camera not until the camera has been mechanically locked,
e.g. with a perpendicular movement in relation to the direction
of the positioning movement of the camera, which is realized by
a pressing element appearing from below of the locking means 64.
Thus, the sensitive electric means can be protected from mechanical
stresses by this kind of compulsory operating sequence of positioning--securing
the mechanical connection--electric coupling. In particular, this
kind of an arrangement enables the realisation of the electric coupling
and its switching off without any gliding movements of the connecting
means. The connecting arrangement 42B according to FIG. 6 does not
cause mechanical stresses to the means 70 involved with the electric
coupling of the camera 5 and the imaging device even when the camera
is connected to its operational station. The mechanical stresses
on the electric connectors are problematic, especially if the duration
of them is long, as the connection elements may bend with time,
or otherwise be damaged to the extent that the electric contact
starts to fail, or even becomes cut off permanently.
As already partly described above, in the solution according to
FIG. 6 specifically horizontal rails have been used to reduce the
possibility that the expensive camera would slip to the floor unintentionally
during its removal and/or mounting. On the other hand, intention
in using more than one guide rail, as well as in separating the
positioning and the actual locking means to elements of their own,
is to ensure the correct positioning of the camera, regarding which
in slot imaging, in particular in the direction of the width of
the narrow beam, one must especially precise. The solution according
to FIG. 6 of separating the actual mechanical connection from the
electric coupling also reduces e.g. the imminent danger of shortcuts
by unintentional crashes to the camera that could lead to a consequence
of damaging the camera, or the imaging device as a whole, or even
to fatal danger in the form of an electric shock.
The connecting arrangements 42A, 42B of the separate imaging stations
11, 12 can be realized as structurally different so that the camera
5 can be attached to one imaging station 11 only by using a connection
arrangement 60, 70 only compatible with it, and to another imaging
station 12 by using another connection arrangement. Thus it can
be ensured that the camera 5 will always be connected correctly
to each imaging station 11, 12. At the same time, the operational
life time of the electric connectors will be increased when the
number of times of coupling per connector structure is reduced to
half, and even if, despite of the above, one connection arrangement
would be damaged, the camera could still be used at least in one
of the imaging stations during the time the acquisition of a new
camera, or in practice, most likely new connecting means, will last.
As a summary, it can be said that, according to the embodiment
of the invention shown in FIGS. 2, 5, and 6, there are structurally
different connection arrangements for the tomographic and for the
transillumination imaging stations, whereby, respectively, there
are two structurally different connection arrangements in the camera,
and these connection arrangements consist of separate mechanical
connection structures and electric connector elements arranged as
independently functioning elements, one for connection for tomographic
imaging on one hand and the other for transilluminaton imaging connection
on the other. The electric coupling means arranged to the imaging
devices are connected to means for moving them in order to move
them into contact with the coupling means located in the camera,
and when the mechanical connection means are arranged to consist
of separate positioning and locking means for the mechanical connection,
the camera according to this embodiment of the invention can be
attached to the imaging device by one connection arrangement consisting
of two separate connection structures only to a certain kind of
connection arrangement of the imaging station, and only using a
compulsory operating sequence of positioning--securing the mechanical
connection--electric coupling.
Although the invention has been described above mainly by using
panoramic and cephalometric imaging applications as examples, it
can naturally also be used in connection with any other corresponding
imaging applications. For example, according to the invention, any
radiation that can be detected by semiconductor sensors can be used.
The invention is especially useful in the imaging applications
of medical technology where x-ray or gamma ray radiation is typically
used, or in biotechnological applications where beta radiation is
typically used. Further, the invention can be applied to industrial
testing and quality control methods utilizing transillumination.
For those professed in the art, it is evident that, especially
with developing technology, the basic idea of the invention is realizable
in many ways, and the embodiments will not be limited by the above
examples, but they can vary within the scope of protection defined
in the attached claims.
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