U.S. patent application number 12/122269 was filed with the patent office on 2009-11-19 for system and method for patient positioning in cone-beam tomography.
This patent application is currently assigned to Sirona Dental Systems GmbH. Invention is credited to Christian Beckhaus, Dieter Thoma.
Application Number | 20090285356 12/122269 |
Document ID | / |
Family ID | 40933177 |
Filed Date | 2009-11-19 |
United States Patent
Application |
20090285356 |
Kind Code |
A1 |
Thoma; Dieter ; et
al. |
November 19, 2009 |
SYSTEM AND METHOD FOR PATIENT POSITIONING IN CONE-BEAM
TOMOGRAPHY
Abstract
A device for positioning a patient within an image volume of a
cone-beam tomography system. The device includes a volume indicator
adapted to indicate at least a front boundary of the image volume
and having a horizontal indicator for horizontal alignment. The
device also includes a head clamp adapted to position at least a
portion of the head of the patient within the front boundary of the
image volume indicated by the volume indicator.
Inventors: |
Thoma; Dieter; (Einhausen,
DE) ; Beckhaus; Christian; (Darmstadt, DE) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
1290 Avenue of the Americas
NEW YORK
NY
10104-3800
US
|
Assignee: |
Sirona Dental Systems GmbH
Bensheim
DE
|
Family ID: |
40933177 |
Appl. No.: |
12/122269 |
Filed: |
May 16, 2008 |
Current U.S.
Class: |
378/20 ;
378/208 |
Current CPC
Class: |
A61B 6/14 20130101; A61B
6/04 20130101; A61B 6/032 20130101; A61B 6/0421 20130101 |
Class at
Publication: |
378/20 ;
378/208 |
International
Class: |
A61B 6/00 20060101
A61B006/00; H05G 1/00 20060101 H05G001/00 |
Claims
1-13. (canceled)
14. A method of positioning a patient within an image volume for a
cone-beam tomography examination using a visual aid, comprising the
steps of: restricting lateral movement of a head of the patient;
aligning the head of the patient in a substantially horizontal
plane relative to a horizontal indicator of the visual aid;
restricting forward movement of the head of the patient; and
checking that at least a portion of the head of the patient is
within a front boundary of the image volume defined by the visual
aid.
15. The method as set forth in claim 14, wherein the front boundary
of the image volume is spherical.
16. The method as set forth in claim 14, wherein the front boundary
of the image volume is cylindrical.
17. A method of performing a cone-beam tomography examination of a
patient, comprising the steps of: restricting lateral movement of a
head of the patient; aligning the head of the patient in a
substantially horizontal plane relative to a horizontal indicator
of a volume indicator; restricting forward movement of the head of
the patient; checking that at least a portion of the head of the
patient is within a front boundary of an image volume defined by
the volume indicator; rotating an x-ray source and a detector
around the head of the patient to create a plurality of
two-dimensional images; and creating a three-dimensional image
based on the plurality of two-dimensional images.
18. The method as set forth in claim 17, wherein the front boundary
of the image volume is spherical.
19. The method as set forth in claim 17, wherein the front boundary
of the image volume is cylindrical.
20. The method as set forth in claim 17, further comprising:
measuring a position of the head; calculating a position of the
patient based on a result obtained by the measuring; and
re-positioning the patient based on a result obtained by the
calculating.
21. The method as set forth in claim 17, further comprising:
measuring a position of the head; calculating a position of the
patient based on a result obtained by the measuring; and
programming a scanning trajectory associated with the cone-beam
tomography examination based on a result obtained by the
calculating.
22. The method as set forth in claim 17, further comprising:
measuring a position of the head; calculating a position of the
patient based on a result obtained by the measuring; and adjusting
x-ray parameters used in the cone-beam tomography examination based
on a result obtained by the calculating.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to the field of
cone-beam tomography systems, and more particularly to systems and
methods for positioning patients in such systems.
[0003] 2. Related Art
[0004] Cone beam computed tomography (CT) systems are widely
employed and have many applications. In particular, they are
becoming increasingly useful and prevalent within the dental
industry. Such systems can be useful in the dental industry for a
number of diagnostic and treatment procedures, including implants,
temporomandibular joint (TMJ), orthodontics, impaction,
orthognathic surgery, airway/sleep apnea studies, etc.
[0005] In x-ray imaging, an x-ray image of an object is created
when x-rays are transmitted from a source through the object and
collected on an image sensor or detector The amount of x-ray
radiation that reaches the sensor is related to the amount of
attenuation that the x-ray encounters in the corresponding path
through the object.
[0006] Broadly, computed tomography is a technique of
reconstructing a three-dimensional image from a sequence of
two-dimensional projection images. CT systems capture
two-dimensional images and employ reconstruction algorithms to
create three-dimensional images. Multiple projection images are
used at different source-detector radiation angles relative to the
object to obtain the required information to isolate a single plane
in the object or create a complete three-dimensional
reconstruction.
[0007] Cone-beam tomography directly captures three-dimensional
information in a single scan. In cone-beam tomography, an x-ray
source generates a cone-shaped illumination that is captured by a
two-dimensional area detector. The source-detector assembly is
scanned around the patient, resulting in the capture of a sequence
of two-dimensional projection images. A direct three-dimensional
reconstruction is then performed.
[0008] In a cone-beam tomography examination, it is useful for the
patient to remain stationary in an assumed volume of space while
the x-ray source and the source-detector assembly are scanned
around the patient to capture the sequence of two-dimensional
images in that assumed volume of space. However, it has been
discovered that positioning the patient properly within that image
volume, such as an orthodontic patient, presents a great clinical
challenge and can affect image quality.
SUMMARY OF THE INVENTION
[0009] The present invention can provide in at least one
embodiment, a system, method, apparatus, and program that can
achieve accurate and precise positioning of a patient in a
cone-beam tomography examination, such as for an orthodontic
patient.
[0010] Before describing the present invention in detail, it is to
be understood that the practice of the present invention employs,
unless otherwise indicated, conventional methods of cone-beam
tomography and processing as known by those having ordinary skill
in the art. The present invention is not limited to particular
formulations or process parameters as such may, of course,
vary.
[0011] The present invention in accordance with one embodiment
provides a device for positioning a patient within an image volume
of a cone-beam tomography system. The device includes a head clamp
having an ear tube attached at each of two ends adapted to fix the
patient in the auditory canals, and having a head support adapted
to further restrict movement of the patient. The head clamp
registers the condyles of the patient with respect to the image
volume.
[0012] The head support may restrict movement of the patient in the
front or rear directions. The head clamp may further include a
volume indicator adapted to indicate at least a front boundary of
the image volume and having a horizontal indicator for horizontal
alignment.
[0013] The present invention in accordance with another embodiment
provides a device for positioning a patient within an image volume
of a cone-beam tomography system. The device includes a volume
indicator adapted to indicate at least a front boundary of the
image volume and having a horizontal indicator for horizontal
alignment. The device also includes a head clamp adapted to
position at least a portion of the head of the patient within the
front boundary of the image volume indicated by the volume
indicator.
[0014] The head clamp may include (1) a plurality of ear tubes at
each end adapted to restrict lateral movement of a head of the
patient and facilitate alignment of the head of the patient in a
substantially horizontal plane relative to the horizontal
structure, and (2) a forehead alignment mechanism adapted to
restrict forward movement of the head of the patient. The head
clamp may be adjustable. Further, the front boundary of the image
volume may be spherical or cylindrical, and the horizontal
indicator may be a laser.
[0015] The device may further include a measuring unit adapted to
measure a position of the head clamp, a calculating unit adapted to
calculate a position of the patient based on a result obtained by
the measuring unit, and a directing unit adapted to direct
re-positioning of the patient based on a result obtained by the
calculating unit.
[0016] The device may further include a measuring unit adapted to
measure a position of the head clamp, a calculating unit adapted to
calculate a position of the patient based on a result obtained by
the measuring unit, and a programming unit adapted to program a
scanning trajectory of the cone-beam tomography system based on a
result obtained by the calculating unit.
[0017] The present invention in accordance with one embodiment
provides a method of positioning a patient within an image volume
for a cone-beam tomography examination using a visual aid,
including (a) restricting lateral movement of a head of the
patient, (b) aligning the head of the patient in a substantially
horizontal plane relative to a horizontal indicator of the visual
aid, (c) restricting forward movement of the head of the patient,
and (d) checking that at least a portion of the head of the patient
is within a front boundary of the image volume defined by the
visual aid. The front boundary of the image volume may be spherical
or cylindrical.
[0018] The present invention in accordance with one embodiment
provides a method of performing a cone-beam tomography examination
of a patient, including (a) restricting lateral movement of a head
of the patient, (b) aligning the head of the patient in a
substantially horizontal plane relative to a horizontal indicator
of a volume indicator, (c) restricting forward movement of the head
of the patient, (d) checking that at least a portion of the head of
the patient is within a front boundary of an image volume defined
by the volume indicator, (e) rotating an x-ray source and a
detector around the head of the patient to create a plurality of
two-dimensional images, and (f) creating a three-dimensional image
based on the plurality of two-dimensional images.
[0019] Further features and advantages of the present invention as
well as the structure and operation of various embodiments of the
present invention are described in detail below with reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The features and advantages of the present invention will
become more apparent from the detailed description set forth below
when taken in conjunction with the drawings in which like reference
numbers indicate identical or functionally similar elements.
[0021] FIG. 1 is an illustration showing a portion of a device for
orthodontic patient positioning in cone-beam tomography according
to an embodiment of the present invention.
[0022] FIG. 2 is a perspective view showing a cone-beam tomography
system for orthodontic patient positioning according to an
embodiment of the present invention incorporating the device shown
in FIG. 1.
[0023] FIG. 3 shows a close-up front view of the device shown in
FIG. 2 according to an embodiment of the present invention.
[0024] FIG. 4 shows a close-up left side view of a portion of the
device shown in FIG. 2 according to an embodiment of the present
invention.
[0025] FIG. 5 shows a right side view of the device shown in FIG. 4
according to an embodiment of the present invention.
[0026] FIG. 6 is a flowchart showing a method for patient
positioning in cone-beam tomography according to an embodiment of
the present invention.
[0027] FIG. 7 is a block diagram showing in more detail a system
200 for cone-beam tomography according to an embodiment of the
present invention.
[0028] FIG. 8 is a flowchart showing a method for patient
positioning in cone-beam tomography according to another embodiment
of the present invention.
[0029] FIG. 9 is a flowchart showing a method for patient
positioning in cone-beam tomography according to another embodiment
of the present invention.
[0030] FIG. 10 is an architecture diagram of an example data
processing system or device which can be used in connection with an
embodiment of the present invention.
DETAILED DESCRIPTION
[0031] Typical positioning aids for patients in CT or cone-beam
tomography, as known in the art, are generally placed below a
patient's chin, on the back of the head, on the lateral aspects of
the head (sometimes within the ears), and between the patient's
teeth. For example, the patient typically sits in a chair, rests
his chin on a chin rest, fits ear tubes into his ears, and bites
down on a bite block, thereby restricting the patient's movement
and aligning him for the cone-beam examination.
[0032] In known techniques, based upon such positioning tools, the
clinician attempts to position the patient so that the relevant
anatomical landmarks, e.g., the condyles or the soft tissue
silhouette, will appear in the image volume of the scan. However,
it has been discovered that patient positioning using such
techniques can be difficult, inefficient, and, if the end result is
not accurate, can require multiple exposures and unintended dosage.
Typically, the most clinically accurate cone-beam tomography images
require that a patient is positioned with the condyles or the soft
tissue silhouette coincident with the machine's image volume. Using
known techniques it can be difficult to register the condyles or
soft tissue silhouette within the image volume, particularly since
the features of each patient can vary, and to keep the patient
tightly positioned within that volume.
[0033] Furthermore, it has been discovered that using a chin rest
as in known techniques, it can be difficult to fix a patient with
his or her mouth closed and obtain suitable images, since the chin
rest can compress the soft tissue of the patient's chin.
[0034] Moreover, it has been discovered that using a bite block as
in known techniques, such as for an orthodontic patient, can
distort the relationship (e.g., in distances and angles) between
various anatomic landmarks that an orthodontist is interested in.
Accordingly, such distortion can prevent or reduce the ability to
obtain accurate occlusal measurements.
[0035] The present invention offers a fresh approach, and provides,
at least in one embodiment, a system, method, apparatus, and
program for orthodontic patient positioning in cone-beam
tomography. In particular, the present invention provides, at least
in one embodiment, a system, method, apparatus, and program for
registering the condyles or the soft tissue silhouette of the
patient within the imaging volume of a cone-beam tomography
machine. Whereas a variety of positioning aids are known and
employed within commercial systems, it has been discovered that
such positioning aids are apt to be inaccurate or cumbersome, or
both, and can often result in an image of only modest quality.
[0036] Accordingly, accurate registering of the patient's condyles
or soft tissue silhouette with regard to the image volume can be
achieved using the present invention, so that enhanced cone-beam
tomography images can be produced. Because cone-beam tomography
scans typically have limited x-ray size, the present invention is
advantageous in that it can optimize the scan by increasing the
amount of anatomy that is registered within the image volume of the
scan. Accordingly, the present invention in accordance with an
example embodiment can provide a cone-beam tomography system for a
patient using simple positioning and accurate imaging.
[0037] FIG. 1 is an illustration showing a portion of a device 10
for patient positioning in cone-beam tomography according to an
embodiment of the present invention. It is noted that FIG. 1 does
not show certain features of the device 10 that are shown in the
views of FIGS. 2-5, such as volume indicator 28 that is described
below in connection with those figures.
[0038] FIG. 1 shows an image volume 12 in which a cone-beam
tomography scan captures images of a patient's anatomical features
14, including the condyles 15. Other features shown in FIG. 1
include the patient's nasion 17, nose tip 19, and a point on the
patient's chin 21. It is of course to be understood that the image
layer 12 of a cone-beam tomography scan may vary and that various
cone-beam tomography scans may have image volumes of varying shapes
and sizes.
[0039] In FIG. 1, ear tubes 16 located at an end of a position
bracket 18 are inserted into the patient's ears for lateral (side
to side) positioning, and to aid in horizontal positioning as
described further below. A front alignment mechanism 22 aids in
positioning, and reference numeral 24 denotes empty space in a
front region of the image volume 12 that naturally exists, due to
the shape of the patient's face, even with an optimum fit of the
patient's anatomical features 14 within the image volume 12. The
present invention can enable all of the relevant anatomy to be
registered in the image volume 12 of a scan.
[0040] FIG. 2 is a perspective view showing a cone-beam tomography
system 200 for patient positioning according to an embodiment of
the present invention, incorporating the device 10 shown in FIG. 1.
More particularly, FIG. 2 is a perspective view including the
portion of the device 10 shown in FIG. 1; FIG. 2 also shows certain
features of the present invention that are not shown in FIG. 1,
including, for example, the volume indicator 28 described
below.
[0041] The device 10 shown in FIG. 2 includes ear tubes 16, head
clamp 18, head rest 26, volume indicator 28, and knobs 20, 30, and
34 (partially obscured in FIG. 2). The head rest 26 aids in front
positioning of a patient's head and in stabilization of a suitable
angular position of the patient's occlusal layer. The position
bracket or head clamp 18, together with the ear tubes 16 located at
the ends of the head clamp 18, aid in lateral and horizontal
positioning of the patient. In particular, the ear tubes 16, which
are gently fitted into the patient's ears by the clinician, can
operate to restrict lateral (side to side) movement and can enable
the clinician to pivotally adjust or tilt the patient's head about
an imaginary axis through the ear tubes for horizontal alignment as
further described below. Accordingly, due to the relatively short
distance between the condyles and the auditory canal, the ear tubes
can enable the patient's condyles or soft tissue silhouette to be
registered within the image volume of the cone-beam tomography
system 200, such that the physical space to be occupied by the
relevant anatomical features of the patient can be related to the
image volume.
[0042] The knobs 20 and 34 enable the clinician to adjust the
position of the head rest 26 and the head clamp 18 for an
individualized or custom patient fit. With knob 20, the width of
the head clamp 18 can be adjusted. With knob 34, the vertical
movement of the head rest 26 can be released and blocked to adjust
the vertical position of the patient. The head rest 26 is
adjustable vertically via knob 34 and horizontally via knob 35 (see
FIG. 5) to accommodate different patients. The clinician can
control the standard functions of the cone-beam tomography system
using control panel 32.
[0043] The device 10 includes, as noted, a volume indicator 28,
which provides a visual aid to further aid in the positioning of a
patient so that the patient's condyles or soft tissue silhouette
can be registered within the image volume of the cone-beam
tomography system 200. The volume indicator 28 in the example
embodiment shown in FIG. 2 is comprised of two half-moon or
parabolically shaped vertical structures 28a and 28b, along with
horizontal structure 28c, which together help define at least a
portion of a front boundary that the patient should be positioned
within in order for the patient's condyles or soft tissue
silhouette to appear within the machine's image volume. That is,
the volume indicator 28 indicates the physical space defining at
least a portion of the machine's image volume, and aids the
clinician in visualizing where the image volume is.
[0044] FIGS. 3 and 4 show close-up front and left side views,
respectively, of the device 10 shown in FIG. 2; though it is to be
noted that in FIG. 3 the head clamp 18 is not shown. FIG. 4
includes a forehead pad 33, located at the end of the front
alignment mechanism 22, which is part of the head rest 26, and
shows a side view of the volume indicator 28 and the physical space
defined thereby. A clinician can position a patient using the
volume indicator 28 as a visual aid or reference, in order to bring
the patient within the outer rim of the image layer as referenced
for visual aid purposes by the volume indicator 28. The clinician
can optimize imaging by adjusting the forehead pad 33 until it
touches the patient's forehead, such that the patient's nose can be
fixed at least close to the image volume indicated by the volume
indicator 28. Accordingly, the condyles or soft tissue silhouette
can be registered in the image layer while, for example, the nose,
which does not need to be registered for an orthodontic patient,
may not be.
[0045] FIG. 5 is a right side view of the device 10 shown in FIG. 4
according to an embodiment of the present invention. FIG. 5 shows
more clearly where the ear tubes 16 are fitted in the patient's
ears, and also shows more clearly the adjustability of the head
clamp 18. The lines indicating measurement values on vertical
support 36 show that the head clamp 18 can be adjusted in the
vertical and horizontal directions using knobs 34 and 35.
[0046] Accordingly, the device 10 according to an embodiment of the
present invention as shown in FIGS. 1-5 is adjustable by the
clinician in various ways as described herein in order to aid the
clinician in bringing the patient's condyles or soft tissue
silhouette within the image volume of the cone-beam tomography
system 200 using the volume indicator 28 as a visual aid.
[0047] It is of course to be understood that the details of the
present invention are not limited by the example embodiment shown
in FIGS. 1-5, and that various modifications can be made to this
example embodiment, as would readily be understood by a person
having ordinary skill in the art. For example, the present
invention according to one embodiment can have a rear head pad
along with or instead of the forehead pad 33, to provide rear head
support. Accordingly, restriction of the patient's head in the
forward and backward directions can be achieved, which can prevent
the patient from nodding and thereby de-stabilizing his or her
head.
[0048] FIG. 6 is a flowchart showing a method 100 for patient
positioning in cone-beam tomography according to an embodiment of
the present invention. The method 100 can use a cone-beam
tomography system such as system 200 of FIGS. 1-5 which includes
positioning device 10. By virtue of the method shown in FIG. 6, the
patient's condyles or soft tissue silhouette can be brought within
the image volume 12 of the scan performed by the cone-beam
tomography system 200, which can result in a more useful image.
[0049] In step 102, the clinician brings the patient's head inside
the position bracket or head clamp 18. The clinician fits the ear
tubes 16 into the patient's ears and pivotally adjusts or tilts the
patient's head on an imaginary axis through the ear tubes 16 until
the patient's head is in substantial alignment with the horizontal
plane defined by the horizontal structure 28c. Accordingly, the
patient's head is adjusted or pivoted vertically (i.e., up and down
about that imaginary axis) until it is fixed in substantial
horizontal alignment with the horizontal structure 28c of the
volume indicator 28. This is the preferred position for taking an
image. The ear tubes 16 also keep the patient aligned in a
substantially vertical or lateral (side to side) direction.
Accordingly, the patient's head is aligned substantially
horizontally and laterally.
[0050] In step 104, the clinician adjusts the forehead pad 33 of
the head rest 26 until it touches the patient's forehead, without
substantially changing the established horizontal alignment. Thus,
the patient is fixed in the head rest 26. In step 106, the
clinician confirms that at least a portion of the patient's head is
positioned within a front boundary of the image volume as indicated
by the volume indicator 28, and the clinician re-positions the
patient according to that indicated image volume if necessary. The
device 10 may also, in one embodiment, include laser lights or LEDs
(not shown) to aid in optimum positioning.
[0051] It is noted that by virtue of the method of FIG. 6, the
clinician or doctor can determine before the scan whether all
relevant anatomic structures can be imaged in one cone-beam
tomography scan. If the clinician or doctor determines that all
relevant anatomic structures may not be imaged in one scan,
however, the clinician can position the patient in favor of, for
example, either the soft tissue silhouette (e.g., the nose or chin)
or the condyles, depending on which anatomy is more relevant to the
specific diagnostic or planning purpose.
[0052] As can be seen from the device 10 of FIGS. 1-5 and the
method 100 of FIG. 6, the present invention according to one
embodiment can utilize at least three points for positioning an
orthodontic patient in a cone-beam tomography examination: both of
the patient's ears and the patient's forehead. In this embodiment,
there are two degrees of freedom available for adjusting the
patient: vertically and horizontally, as described. Accordingly,
the present invention according to one embodiment can provide a
system and method for rigidly fixing the patient in an image volume
for a cone-beam scan.
[0053] Moreover, the present invention according to one embodiment
can enable a representation of the occlusion bite without
compressing the soft tissue of the chin region, since the present
invention according to one embodiment does not use a chin rest.
Using the ear tubes 16 as described herein is advantageous because
there is not much soft tissue in between.
[0054] Furthermore, the present invention according to one
embodiment does not use a bite block for patient positioning. As
explained above, a bite block, as in known techniques, such as for
an orthodontic patient, can distort the relationship between
various anatomic landmarks that an orthodontist is interested in.
Accordingly, the present invention according to one embodiment does
not use a bite block and can provide more accurate occlusal
measurements.
[0055] It is of course to be understood that the present invention
is not limited to the example embodiments shown in FIGS. 1-6. For
example, other embodiments of the volume indicator 28 can be
readily envisioned, e.g., depending on the type of detector used.
As one example, while the shape of each vertical structure 28a and
28b of the volume indicator 28 is spherical, if a rectangular
flatpanel detector is used, the image volume would be cylindric
instead of spherical, and the front boundary of the image volume
would then be rectangular instead of spherical. Accordingly, the
shape of each vertical structure 28a and 28b would be straight, and
not spherical, to represent that rectangular front boundary. The
present invention is also not limited to only two vertical
structures 28a and 28b, and any suitable number of such structures
can suffice. Furthermore, instead of the structures 28a, 28b, and
28c being physical or non-electrical elements, any or all of them
may be electrical elements such as a laser. Other variations are
readily envisioned in view of this description.
[0056] In another embodiment of the present invention, the device
10 of FIGS. 1-5 can be used without the volume control 28. That is,
the device 10, including, e.g., the ear tubes 16, head clamp 18,
front alignment mechanism 22, head rest 26, forehead pad 33, knobs
20, 34, and 35 can be used without the volume control 28. For
example, the head clamp 18 including the ear tubes 16 can be used
to fix the patient in his auditory canals, and the forehead pad 33
can restrict movement of the patient in the front direction. Or, a
rear head pad (not shown) can restrict movement of the patient in
the rear direction. Accordingly, the head clamp 18 including the
ear tubes 16 can register the relevant anatomy (e.g., the condyles
or the soft tissue silhouette) of the patient within the image
volume 12. This can provide for rigid fixation of the patient
without certain elements distorting the terminal occlusion (bite
block) or the soft tissue silhouette (chin rest). This embodiment
can be particularly useful for larger image volumes, for
example.
[0057] It is also of course to be understood that while the example
embodiments of the present invention as described in FIGS. 1-6
relate generally to positioning of an orthodontic patient, it is of
course to be understood that the present invention is not limited
to such example application and that the present invention can be
used in other applications or cone-beam tomography scans. Such
applications may include, for example, medical applications such as
craniofacial (diagnostics, treatment, prosthetics, etc.), other
dental applications (diagnostics or treatment for hard tissue or
soft tissue applications, etc.), and others. Such applications may
also include, for example, non-medical applications such as in
forensics.
[0058] FIG. 7 is a block diagram showing in more detail the system
200 for cone-beam tomography according to an embodiment of the
present invention. The system 200 including the positioning device
10 shown in FIGS. 1-5 can enable optimal positioning of a patient
such that the relevant anatomy, e.g., the condyles or soft tissue
silhouette of the patient, can be registered within the image
volume of the cone-beam tomography system 200.
[0059] The machine mechanics unit 206-1 of the motion platform 206
directs the x-ray source 206-2 and the x-ray detector 206-3
accordingly to perform scanning. The x-ray detector or receiver
206-3 may be large amorphous silicon thin film transistors (TFT),
charge-coupled device (CCD) detectors coupled to image
intensifiers, or any other suitable type of digital sensor or
radiation receptor.
[0060] Scanning of the patient is performed and the digital data
can be transmitted to an image processing system 208, from which it
can be processed (e.g., to perform a three-dimensional
reconstruction) and presented to the clinician and to the patient.
The image processing system 208 can include a central processing
unit (CPU) 208-1 and can process the signal to produce an image on
an associated output device (such as the monitor 208-4 or the
printer 208-5). The image processing system 208 allows the user to
view and analyze the dental images that the system creates. The
image processing system 208 may be, for example, a desktop, tower,
laptop, or notebook computer, equipped with software for processing
the data provided to it by the sensor 206-3. The image processing
system 208 may be connected to or have built in one or more input
devices, such as a keyboard 208-2 and a mouse 208-3, and one or
more output devices, such as the display or monitor 208-4 and the
printer 208-5.
[0061] These devices allow the user to view and analyze the dental
images that the system creates through a graphical user interface,
and can also allow the user to control the operation of the system.
For example, an interface screen can enable a user to easily access
the information and initiate analysis. The image processing system
can also include or be connected to a storage device (not shown),
such as a hard drive, for permanent storage of the images in
patient files. Other potential storage devices include floppy
disks, ZIP drives, magnetic tape, and optical medium. A variety of
computer program products comprising, in general, a
computer-readable medium, can be used with the present
invention.
[0062] The software might run on a PC-compatible, Macintosh.RTM.,
or Unix.RTM.-based computer, among others. In one embodiment the
software runs on a PC-compatible computer with a Pentium.RTM.-based
CPU running Windows 98.RTM., Me.RTM., 2000.RTM., XP.RTM., or
Vista.RTM.. Of course, these examples are not meant to be limiting
in any way, and the software can be written to be compatible with
other or newer operating systems as well. In another embodiment,
the software can be written to be complementary to that used for
acquiring intra-oral images and for standard panoramic, video, and
cephalometric examinations. The software also can preferably be
compatible with dental practice management software.
[0063] The computer preferably contains at least 1 GB of RAM and,
for example, 500 GB of hard disk space to store the software and
image files. The display would preferably be optimized for video
images in color. It might also be advantageous to bundle the system
with a backup system for storing image and patient data.
[0064] The system 200 of FIG. 7 also includes one or more measuring
units 204 such as a position sensor which can automatically take
electrical measurements of the positions of various elements of
device 10 (for example, the head clamp 18, the head rest 26, the
forehead pad 33, etc.), after the patient is fitted therein or is
positioned using the method of FIG. 6, for example. The measuring
unit 204 can then transmit those measurements to a processor such
as the image processing system 208 or to a separate processor (not
shown).
[0065] The processor can calculate the position of the patient's
relevant anatomy (e.g., the soft tissue silhouette or the condyles)
with respect to the image volume from this data. For that purpose,
the position of the ear tubes 16 with respect to the reference
coordinate system of the cone-beam tomography system 200 can be
calculated from the horizontal and vertical positions of the device
10 and the known geometric dimensions of the device 10 itself.
Higher precision can be attained by including the width of the head
clamp 18 in the calculation. With the well known and fixed spatial
relation between the auditory canal and the condyles, the processor
can calculate the position of the patient's condyles, for example,
with respect to a reference coordinate system of the system 200.
The system 200 thus knows a precise position of the patient and the
position and shape of the image volume.
[0066] Using this information, the system 200 can calculate the set
values for the horizontal and vertical position of the device 10
that would correspond to the image volume position. The system 200
can then optimize the positioning of the patient by directing the
clinician to position or re-position the patient according to the
calculated set values of the device 10. Such direction can take any
suitable form, including audio instructions or visual instructions
such as sounds (e.g, voice) or LEDs, for example, using known
techniques. These instructions can be provided by the image
processing system 208.
[0067] Alternatively, the processor can optimize positioning by (1)
calculating the required image volume, given the position of the
patient as calculated from the electrical measurements as described
above, and (2) programming the motion platform 206 to achieve the
required image volume. In this way, the position of the image
volume can be optimized by the system 200 using known algorithms to
ensure that the relevant anatomy (e.g., the condyles) lie
completely inside the image volume, for example. The processor can
adjust the scanning trajectory of the motion platform 206 based on
the required image volume, e.g., by moving the rotational center of
the motion platform with additional motors. Drive systems that
allow such a movement are generally used in panoramic x-ray
machines in various layouts. In any event, the processor can send
programming signals to the machine mechanics unit 206-1 of the
motion platform 206, which directs the x-ray source 206-2 and the
x-ray detector 206-3.
[0068] FIG. 8 is a flowchart showing a method 300 for patient
positioning in cone-beam tomography according to another embodiment
of the present invention. The method 300 can use a cone-beam
tomography system such as system 200 of FIGS. 1-5, which includes
positioning device 10. By virtue of the method shown in FIG. 8, the
patient's relevant anatomy (e.g., the condyles or soft tissue
silhouette) can be brought within the image volume 12 of the scan
performed by the cone-beam tomography system 200, which can result
in a more useful image. The method 300 of FIG. 8 can be implemented
after the patient is fitted into device 10 or after the patient is
positioned using the method of FIG. 6, for example. As an example,
computer-readable medium can store a computer program which
performs the steps of the method 300 of FIG. 8.
[0069] In step 302, the measuring unit 204 automatically (or in
response to a user-instructed command or other type of command)
takes electrical measurements of the positions of various elements
of device 10 (for example, the head clamp 18, the head rest 26, the
forehead pad 33, etc.). In step 304, those measurements are
transmitted to a processor, such as the image processing system 208
or a separate processor (not shown), and the processor calculates
the position of the patient's relevant anatomy (e.g., the condyles
or soft tissue silhouette) with respect to the image volume from
this measurement data.
[0070] For that purpose, the position of the ear tubes 16 with
respect to the reference coordinate system of the cone-beam
tomography system 200 can be calculated from the horizontal and
vertical positions of the device 10 and the known geometric
dimensions of the device 10 itself. Higher precision can be
attained by including the width of the head clamp 18 in the
calculation. With the well known and fixed spatial relation between
the auditory canal and the condyles, the processor can calculate
the position of the patient's condyles, for example, with respect
to a reference coordinate system of the system 200. The system 200
thus knows a precise position of the patient and the position and
shape of the image volume.
[0071] Using this information and known algorithms, in step 306 the
system 200 calculates the set values for the horizontal and
vertical position of the device 10 (and thus a positioning of the
patient) that would optimally correspond to the image volume. In
step 308, the system 200 then directs the clinician to position or
re-position the patient according to the calculated set values of
the device 10. Such direction can take any suitable form, including
audio instructions or visual instructions such as sounds (e.g,
voice) or LEDs, for example, using known techniques. These
instructions can be provided by the image processing system
208.
[0072] FIG. 9 is a flowchart showing a method 500 for patient
positioning in cone-beam tomography according to another embodiment
of the present invention. A computer-readable medium can store a
computer program which performs the steps of the method 500 of FIG.
9.
[0073] Steps 502 and 504 of FIG. 9 are similar to steps 302 and 304
in FIG. 8. In step 506 of FIG. 9, the processor can optimize
positioning by (1) calculating the required image volume, given the
position of the patient as calculated from the electrical
measurements as described above, and (2) programming the motion
platform 206 to achieve the required image volume. In this way, the
position of the image volume can be optimized by the system 200
using known algorithms to ensure that the relevant anatomy (e.g.,
the condyles) lie completely inside the image volume, for example.
The processor can adjust the scanning trajectory of the motion
platform 206 based on the required image volume, e.g., by moving
the rotational center of the motion platform with additional
motors. Drive systems that allow such a movement are generally used
in panoramic x-ray machines in various layouts. In any event, the
processor can send programming signals to the machine mechanics
unit 206-1 of the motion platform 206, which directs the x-ray
source 206-2 and the x-ray detector 206-3.
[0074] FIG. 10 is an architecture diagram of an example data
processing system or device 400, which, according to an example
embodiment, can form individual ones of the components 204, 206-1,
and 208 of FIG. 7. Data processing system 400 includes a processor
402 coupled to a memory 404 via system bus 406. Processor 402 is
also coupled to external Input/Output (I/O) devices (not shown) via
the system bus 406 and an I/O bus 408, and at least one
input/output user interface 418. Processor 402 may be further
coupled to a communications device (interface) 414 via a
communications device controller 416 coupled to the I/O bus 408.
Processor 402 uses the communications device 414 to communicate
with a network, such as, for example, a network as shown in FIG. 7,
and the device 414 may have one or more input and output ports.
Device 414 has a data port 419 operably coupled to a network for
sending and receiving data, and may also have one or more
additional input and output ports. A storage device 410 having a
computer-readable medium is coupled to the processor 402 via a
storage device controller 412 and the I/O bus 408 and the system
bus 406. Processor 402 also can include an internal clock (not
shown) to keep track of time, periodic time intervals, and the
like.
[0075] The input/output user interface 418 may include, for
example, at least one of a keyboard, a mouse, a trackball, touch
screen, a keypad, and/or any other suitable type of user-operable
input device(s), and at least one of a video display, a liquid
crystal or other flat panel display, a speaker, a printer, and/or
any other suitable type of output device for enabling a user to
perceive outputted information.
[0076] Processing can be performed, for example, by a processor
that communicates with the measuring unit 204 and the cone-beam
tomography machine, by a processor embedded in the machine, or by
any other suitable arrangement. The processor can read the data
from, e.g., the measuring unit 204 and generate a scanning
trajectory or instructions for the clinician for the cone-beam
tomography machine. Modulation of mA of the x-ray source may also
be implemented.
[0077] Storage device 410 having a computer readable medium is
coupled to the processor 402 via a storage device controller 412
and the I/O bus 408 and the system bus 406. The storage device 410
is used by the processor 402 and controller 412 to store and
read/write data 410a, and to store program instructions 410b used
to implement at least part of the procedures described and shown
herein. The storage device 410 also stores various routines and
operating programs (e.g., Microsoft Windows, UNIX.RTM./LINUX.RTM.,
or OS/2.RTM.) that are used by the processor 402 for controlling
the overall operation of the system 400. At least one of the
programs (e.g., Microsoft Winsock.RTM.) stored in storage device
410 can adhere to TCP/IP protocols (i.e., includes a TCP/IP stack),
for implementing a known method for connecting to the Internet or
another network, and may also include web browser software, such
as, for example, Microsoft Internet Explorer (IE) and/or Netscape
Navigator, for enabling a user of the system 400 to navigate or
otherwise exchange information with the World Wide Web (WWW).
[0078] In operation, processor 402 loads the program instructions
410b from the storage device 410 into the memory 404. Processor 402
then executes the loaded program instructions 410b to perform any
of the example methods described herein, for operating the system
200.
[0079] The present invention or any part(s) or function(s) thereof
may be implemented using hardware, software or a combination
thereof and may be implemented in one or more computer systems or
other processing systems. It is noted that the various components
of the present invention may be controlled by one or more modules
coupled to the various components. The modules can operate in
accordance with software control programs and operating routines
stored in an associated memory or memories. The modules and their
sub-modules can write and/or read information to/from the memory or
memories, and in this way, can perform operations in accordance
with the system, method, and apparatus of the present invention.
The modules may be implemented using hardcoded computational
modules or other types of circuitry, or a combination of software
and circuitry modules. Software routines for performing the modules
can, in one embodiment, be stored as instructions in a memory and
can be executed by a processor of a control module.
[0080] In an embodiment where the invention or any part(s) or
function(s) thereof are implemented using software, the software
may be stored in a computer program product, a computer program
medium, or a computer-readable medium, and loaded into a computer
system using a removable storage drive, a hard drive, or a
communications interface. The control logic (software), when
executed by a processor, causes the processor to perform the
functions of the invention as described herein.
[0081] In this document, the terms "computer program medium" and
"computer usable medium" are used to refer generally to media such
as a removable storage drive, a hard disk installed in a hard disk
drive, and signals. Also, "computer-readable medium" is used to
refer generally to media such as a storage drive, CD, hard drive or
other tangible object that can store a program. These computer
program products provide software to the system.
[0082] While various embodiments of the present invention have been
described above, it should be understood that they have been
presented by way of example, and not limitation. It will be
apparent to persons skilled in the relevant art(s) that various
changes in form and detail can be made therein without departing
from the spirit and scope of the present invention. Thus, the
present invention should not be limited by any of the above
described exemplary embodiments, but should be defined only in
accordance with the following claims and their equivalents.
* * * * *