U.S. patent number RE41,197 [Application Number 11/800,521] was granted by the patent office on 2010-04-06 for method and apparatus for cephalometric imaging.
This patent grant is currently assigned to PaloDEx Group Oy. Invention is credited to Panu Kopsala.
United States Patent |
RE41,197 |
Kopsala |
April 6, 2010 |
Method and apparatus for cephalometric imaging
Abstract
The invention relates to a method for cephalometric imaging
using an apparatus (1) which comprises an X-ray source (5), a line
detector camera (8) equipped with a digital detector, which line
detector camera is located to a position far away from the X-ray
source (5) for carrying out cephalometric imaging while the slot of
the line detector camera is substantially vertical. In
cephalometric imaging, an X-ray beam (11) located substantially on
the vertical plane is directed from the X-ray source (5) through
the object being imaged, and the X-ray source (5) is at the same
time turned about the rotation center (13) located between the
X-ray source and the line detector camera (8) in order to scan the
object being imaged in the horizontal direction, whereby the line
detector camera (8) is moved during the scanning movement in such a
way that the ray beam (11) meets the slot (14) of the line detector
camera. In the method, the effective focal spot is transferred from
the rotation center (13) to the focal spot of the X-ray source (5)
by transferring the rotation center by means of a transverse linear
movement (A) with respect to the ray beam (11).
Inventors: |
Kopsala; Panu (Tuusula,
FI) |
Assignee: |
PaloDEx Group Oy
(FI)
|
Family
ID: |
8557596 |
Appl.
No.: |
11/800,521 |
Filed: |
May 4, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
10204104 |
|
6731717 |
|
|
|
PCT/FI01/00137 |
Feb 14, 2001 |
|
|
|
Reissue of: |
10795638 |
Mar 8, 2004 |
06891921 |
May 10, 2005 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Feb 18, 2000 [FI] |
|
|
20000369 |
|
Current U.S.
Class: |
378/38; 378/197;
378/191 |
Current CPC
Class: |
A61B
6/06 (20130101); A61B 6/501 (20130101); A61B
6/589 (20130101); A61B 6/588 (20130101) |
Current International
Class: |
A61B
6/14 (20060101) |
Field of
Search: |
;378/38-40,196,197,191 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Glick; Edward J.
Assistant Examiner: Artman; Thomas R
Attorney, Agent or Firm: Andrus, Sceales, Starke &
Sawall, LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION.Iadd.S.Iaddend.
.[.The present application is a continuation application of U.S.
patent application Ser. No. 10/204,104, filed Oct. 10, 2002, now
U.S. Pat. No. 6,731,717.That application is the U.S. national stage
application of International Application PCT/FI01/00137, filed Feb.
14, 2001, which application was published on Aug. 23, 2001 as
International Publication WO 01/60257. The International
Application claims the priority of Finnish Patent Application
20000369, filed Feb. 18, 2000..].
.Iadd.The present application is a reissue application of U.S.
patent application Ser. No. 10/795,638, filed Mar. 8, 2004, now
U.S. Pat. No. 6,891,921. That application is a continuation of
application Ser. No. 10/204,104, filed as Application No.
PCT/FI01/00137 on Feb. 14, 2001, now U.S. Pat. No. 6,731,717. The
International Application claims the priority of Finnish Patent
Application 20000369, filed Feb. 18, 2000..Iaddend.
Claims
What is claimed is:
1. A method for operating a panoramic imaging apparatus to provide
improved .[.tomographic.]. cephalometric images, the panoramic
imaging apparatus being capable of operating in a mode in which an
X-ray source and radiation sensor, spaced from said .[.radiation.].
.Iadd.X-ray .Iaddend.source at a first distance, are rotated about
an intermediate vertical rotation center to provide a panoramic
image from a subject positioned between the X-ray source and the
radiation sensor, said method comprising the steps of: positioning
a radiation receiver to receive radiation from said X-ray source,
said radiation receiver being located at a second distance from
said X-ray source greater than said first distance; placing a
subject for cephalometric imaging in front of the radiation
receiver; projecting radiation from the X-ray source along a
horizontal radiation path to apply radiation from the X-ray source
to the radiation receiver; carrying out a first motion comprising
rotating the X-ray source .[.about the center of rotation.].
.Iadd.while otherwise maintaining the X-ray source generally
stationary.Iaddend.; carrying out a second motion comprising
horizontally translating the center of rotation in a direction
generally transverse to the radiation path during application of
the radiation to the radiation receiver; .Iadd.wherein the
effective focal spot of the X-ray source is transferred to the
general location of the X-ray source.Iaddend.; and carrying out a
third motion comprising translating the radiation receiver in a
horizontal direction generally transverse to the radiation path,
said first, second, and third motions producing a .[.tomographic.].
cephalometric image from the panoramic imaging apparatus for which
the effective focal point for the X-ray source has been altered in
a manner to reduce differences in vertical and horizontal ratios of
enlargement.
2. The method according to claim 1 further including the step of
collimating the radiation applied to the radiation receiver.
3. An apparatus for providing a .[.tomographic.]. cephalometric
image comprising: a radiation receiver; a panoramic imaging X-ray
source providing radiation along a generally horizontally extending
radiation path for application to said radiation receiver; a
support for said X-ray source, said support having a vertical
rotation center for rotating said X-ray source, said rotation
center being positioned intermediate said radiation receiver and
said X-ray source and closer to said X-ray source than to said
radiation receiver; means for rotating said X-ray source .[.about
said rotation center.]. .Iadd.while otherwise maintaining the X-ray
source generally stationary.Iaddend.; means for generally
horizontally translating said rotation center in a direction
generally transverse to the radiation path; .Iadd.wherein the
effective focal spot of the X-ray source is transferred to the
general location of the X-ray source.Iaddend.; and means for
translating said radiation receiver in a horizontal direction
generally transverse to the radiation path during application of
the radiation to said radiation receiver, the motions provided to
said .[.radiation.]. .Iadd.X-ray .Iaddend.source, rotation center,
and radiation receiver by the respective means producing a
.[.tomographic.]. cephalometric image from a subject positioned in
front of said radiation receiver for which the effective focal
length of the X-ray source has been altered in a manner to reduce
differences in the vertical and horizontal ratios of
enlargement.
4. The apparatus according to claim 3 wherein said radiation
receiver comprises a line detection camera.
5. The apparatus according to claim 3 further including a
collimator for being placed in front of the subject.
.Iadd.6. A method for operating imaging apparatus to provide
improved cephalometric images having reduced differences in
vertical and horizontal ratios of enlargement, the method
comprising the steps of: providing an imaging apparatus comprising
an X-ray source configured to apply radiation to a radiation
receiver spaced apart from the X-ray source by a first distance in
a lateral direction and to a radiation receiver spaced apart from
the X-ray source by a second distance in the lateral direction, the
second distance being greater than the first distance; the imaging
apparatus being capable of operating in a mode in which the X-ray
source and the radiation receiver spaced apart from the X-ray
source by the first distance are rotated about an intermediate
rotation center to provide an image of an object positioned between
the X-ray source and the radiation receiver spaced apart from the
X-ray source by the first distance; placing a subject for
cephalometric imaging between the X-ray source and the radiation
receiver spaced apart from the X-ray source by the second distance;
and taking a cephalometric image of the subject by applying
radiation from the X-ray source to the radiation receiver spaced
apart from the X-ray source by the second distance and
simultaneously translating said rotation center in a direction
generally transverse to the lateral direction so as to transfer the
effective focal spot of the X-ray source towards the X-ray source
in the lateral direction; wherein the X-ray source remains
substantially stationary and the effective focal spot of the X-ray
source is transferred to the general location of the X-ray
source..Iaddend.
.Iadd.7. The method according to claim 6, wherein the imaging
apparatus comprises a first radiation receiver spaced apart from
the X-ray source by the first distance and a second radiation
receiver spaced apart from the X-ray source by the second
distance..Iaddend.
.Iadd.8. The method according to claim 6, further comprising the
step of translating the radiation receiver spaced apart from the
X-ray source by the second distance generally transverse to the
lateral direction so that the radiation receiver is positioned to
continuously receive radiation applied by the X-ray
source..Iaddend.
.Iadd.9. The method according to claim 6, further comprising the
step of operating the imaging apparatus in the first mode by
rotating the X-ray source and the radiation sensor spaced apart
from the X-ray source by the first distance about the intermediate
rotation center to provide an image of the object positioned
between the X-ray source and the radiation receiver spaced apart
from the X-ray source by the first distance..Iaddend.
.Iadd.10. The method according to claim 9, wherein the image of the
object is a panoramic image..Iaddend.
.Iadd.11. The method according to claim 6, wherein the imaging
apparatus comprises a panoramic imaging apparatus configured to
also take cephalometric images..Iaddend.
.Iadd.12. The method according to claim 6, further comprising the
step of collimating the radiation applied to the radiation receiver
spaced apart from the X-ray source by the second
distance..Iaddend.
.Iadd.13. A method for operating an imaging apparatus to provide
improved cephalometric images having reduced differences in
vertical and horizontal ratios of enlargement, the method
comprising the steps of: providing an imaging apparatus extending
in three dimensions, including a length dimension, a width
dimension that is generally perpendicular to the length dimension,
and a height dimension that is generally perpendicular to the
length dimension and generally perpendicular to the width
dimension; wherein the imaging apparatus comprises an X-ray source
configured to apply radiation in the length dimension to a
radiation receiver spaced apart from the X-ray source by a first
distance in the length dimension and to a radiation receiver spaced
apart from the X-ray source by a second distance in the length
dimension, the second distance being greater than the first
distance; the imaging apparatus being capable of operating in a
mode in which the X-ray source and the radiation receiver spaced
apart from the X-ray source by the first distance are rotated about
an intermediate rotation center to provide an image of an object
positioned between the X-ray source and the radiation receiver
spaced apart from the X-ray source by the first distance; placing a
subject for cephalometric imaging between the X-ray source and the
radiation receiver spaced apart from the X-ray source by the second
distance; and taking a cephalometric image of the subject by
applying radiation from the X-ray source to the radiation receiver
spaced apart from the X-ray source by the second distance and
simultaneously translating said rotation center generally in the
width dimension so as to transfer the effective focal spot of the
X-ray source towards the X-ray source in the length dimension;
wherein the X-ray source remains substantially stationary and the
effective focal spot of the X-ray source is transferred to the
general location of the X-ray source..Iaddend.
.Iadd.14. The method according to claim 13, wherein the imaging
apparatus comprises a first radiation receiver spaced apart from
the X-ray source by the first distance and the second radiation
receiver spaced apart from the X-ray source by the second
distance..Iaddend.
.Iadd.15. The method according to claim 13, wherein the imaging
apparatus comprises a panoramic imaging apparatus configured to
also take cephalometric images..Iaddend.
.Iadd.16. The method according to claim 13, further comprising the
step of translating the radiation receiver spaced apart from the
X-ray source by the second distance generally in the width
dimension so that the radiation receiver is positioned to
continuously receive radiation applied by the X-ray
source..Iaddend.
.Iadd.17. The method according to claim 13, further comprising the
step of operating the imaging apparatus in the first mode by
rotating the X-ray source and the radiation sensor spaced apart
from the X-ray source by the first distance about the intermediate
rotation center to provide an image of the object positioned
between the X-ray source and the radiation receiver spaced apart
from the X-ray source by the first distance..Iaddend.
.Iadd.18. The method according to claim 17, wherein the image of
the object is a panoramic image..Iaddend.
.Iadd.19. The method according to claim 13, further comprising the
step of collimating the radiation applied to the radiation receiver
spaced apart from the X-ray source by the second distance..Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method for cephalometric imaging
using an apparatus which comprises an X-ray source, a line detector
camera equipped with a digital detector, which line detector camera
is located to a position far away from the X-ray source for
carrying out cephalometric imaging while the slot of the line
detector camera is substantially vertical, whereby in cephalometric
imaging, an X-ray beam located substantially on the vertical plane
is directed from the X-ray source through the object being imaged,
and the X-ray source is at the same time turned about the rotation
centre located between the X-ray source and the line detector
camera in order to scan the object being imaging in the horizontal
direction, whereby the line detector camera is moved during the
scanning movement in such a way that the ray beam meets the slot of
the line detector camera. The publication U.S. Pat. No. 5,511,106
discloses this type of scanning method for cephalometric
imaging.
SUMMARY OF THE INVENTION
When cephalometric imaging is carried out in the manner described
above, the vertical ratio of enlargement remains the same as
without the scanning movement, but the horizontal ratio of
enlargement, on the other hand, changes because the rotation centre
changes into the effective focal spot instead of the focal spot of
the X-ray source. Accordingly, the object of the present invention
is to provide a method by means of which the ratios of enlargement
in cephalometric imaging can be maintained the same in the vertical
and horizontal directions in cephalometric imaging, which is
carried out by means of the turning movement taking place about the
rotation centre of the X-ray source. A further object is to provide
a method which can be implemented by using existing panoramic X-ray
imaging apparatuses, which already comprise the means needed to
perform the required movements. To achieve this object, the method
relating to the invention is characterised in that in the method,
the effective focal spot is transferred from the rotation centre to
the focal spot of the X-ray source by transferring the rotation
centre by means of a transverse linear movement with respect to the
ray beam.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail in the following, with
reference to the accompanying drawings, in which:
FIG. 1 shows a diagrammatic top view of an apparatus applicable for
the method according to the invention,
FIG. 2 shows diagrammatically a view in principle of a camera used
in the apparatus according to FIG. 1,
FIG. 3 shows diagrammatically the effect of the rotary movement of
the X-ray source on the effective focus, and
FIG. 4 shows diagrammatically the effect of the transfer of the
rotation centre of the rotary movement of the X-ray source on the
effective focus.
DETAILED DESCRIPTION OF THE INVENTION
The apparatus 1 according to FIG. 1 comprises a support part 2,
beneath which is connected a panoramic imaging apparatus 4 which
turns in a pivoting manner around the rotation centre 13, the
imaging apparatus comprising a C arm 7, on one vertical branch 7a
of which is arranged an X-ray source 5 and the primary collimator 6
in its vicinity, and on the other branch 7b a line detector camera
8.
FIG. 2 shows diagrammatically one implementation of a line detector
camera 8, wherein on one side of the camera is formed a slot 14,
behind which, inside the camera 8, is a digital detector 15, for
example, a CCD sensor. The panoramic imaging apparatus 4 and its
operation are, as such, known to a person skilled in the art. In
panoramic imaging, the object to be imaged is placed between the
branch parts 7a, 7b of the C arm by means of appropriate guides and
supports, after which the X-ray source 5 is switched on and the C
arm is rotated about the rotation centre 13, whereby the aperture
of the primary collimator 6 is selected in such a way that the ray
beam 11, which is substantially on the vertical plane, is directed
at the detector 15 behind the substantially vertical slot 14 of the
line detector camera 8 on the branch part 7b of the C arm 7, from
which detector the image data is transmitted further, for example,
to a microprocessor. This process of panoramic imaging will not be
described in greater detail in this connection.
To the support part 2 is connected a supporting arm 3, at the other
end of which is the cephalometric imaging apparatus 10, which
comprises a line detector camera 8 to be placed behind the object
being imaged, and a secondary collimator 9 to be placed in front of
the object being imaged. In cephalometric imaging, the patient's
head is scanned by means of the ray beam 11 from right to left or
vice versa.
In the method according to the invention, cephalometric imaging is
carried out by turning the X-ray source 5 about a rotation centre
13 to image the patient's head 12 by means of a vertically
positioned ray beam 11. FIG. 3 shows a situation where the rotation
centre 13 remains in place, in which case, when the X-ray source 5
turns about the rotation centre, the X-ray beams 11 travel in each
angular position via the rotation centre 13, whereby the rotation
centre 13 becomes the effective focal spot for the radiation coming
through the object in the layer 17 being imaged on the image plane
(detector) 18. In this case, the ratio of enlargement, which is
determined by the ratio of the distance (SID) between the focus and
the image plane to the distance (SOD) between the focus and the
object, is the ratio of the distance between the rotation centre 13
and the image layer 17 to the distance between the rotation centre
13 and the image plane 18.
It is for this reason that, according to the invention, in
cephalometric imaging the rotation centre 13 is arranged to be
transferred by linear movement transversely with respect to the ray
beam 11, as shown by reference marking A in FIG. 1. FIG. 4 shows a
situation where the rotation centre has been transferred by linear
movement from position 13a to position 13b, whereby the focal spot
is transferred to the X-ray source 5, in which case also the
horizontal ratio of enlargement remains the same.
* * * * *