Interventional volume scanner

Details Interventional volume scanner Interventional volume scanner

2001-10-15

2003-09-16

Dunn, Drew A. (Department: 2882)

X-ray or gamma ray systems or devices

Source support

Including movable source

C378S196000

Reexamination Certificate

active

06619840

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to C-arm X-ray systems, and more particularly to a C-arm X-ray system with full volume imaging capability for use in interventional procedures.
Various C-arm X-ray devices and system are known in the art. For example, German patent No. DE 198 39 825 C1 (“the '825 patent”), incorporated herein by reference, discloses an X-ray device in
FIG. 1A
comprising circular support equipment
1
. The circular support equipment includes a C-shaped arm or first ring segment
4
. The first ring segment
4
is attached to the circular support equipment
1
via a first bearing equipment
9
and further includes an X-ray source
2
and an X-ray detector
3
disposed at opposing sides of a patient
7
. The X-ray device of the '825 patent also includes a second ring segment
5
attached to second bearing equipment
12
and head lining rail
13
.
The circular support equipment
1
, first bearing equipment
9
, first ring segment
4
, X-ray source
2
and detector
3
of the '825 patent device may be used to perform conventional fluoroscopy. The second ring segment
5
may be pivoted about a tangential pivot axis to bring the second ring segment
5
into alignment with the first ring segment
4
. This allows (when attached and aligned) 360 degree rotation of the X-ray source
2
and detector
3
about the patient
7
. Hence, the '825 patent devices include an ability to operate as a computer tomography device as well as a conventional C-arm type fluoroscope.
The '825 patent device has its limitations, however. In particular, the second ring segment
5
must be mechanically aligned, brought into contact with, and plugged into (attached to) the first ring segment
4
before the CT mode of operation may be implemented. This requires that a mechanical tenon
28
which fits into a mortise
29
constructed within the second ring segment
5
, as shown in FIG.
1
A.
A bolt
30
is inserted into a bolthole of at least one mechanical tenon
28
in order to lock the first and second ring segments. As such, making the connection requires substantial effort in both the alignment and the locking together of the ring segments.
Moreover, the head lining
13
, the second bearing equipment
12
and berth the equipment
6
take up a substantial volume which is certainly a hindrance to the technical individuals who would utilize the construction to perform both conventional fluoroscopic and CT scanning during an interventional medical procedure. The patient
7
is difficult to access in particular positions because of the structure itself, and the necessary elements required to lock the first and second ring segments.
The '825 patent also includes two additional proposals for realizing the closed circle (ring) with its inherent ability to rotate a full 360 degrees. That is, the '825 patent also includes an embodiment which uses two (2) interleaved c-shaped arcs (FIGS.
5
-
11
).
Another embodiment of the '825 patent is constructed to use two (2) c-shaped arcs connected vertically utilizing a hinge.
Each of the above-mentioned embodiments (i.e., the three (3)-introduced approaches) aim for the generation of a rigid circle or ring that can be used for performing 360° rotations. The basic idea is to use the standard support of the C (
16
in
FIG. 1
of the '825 patent) and simply increase the range of the rotation of the c-shaped connection between tube and detector (
4
,
FIG. 1
of the '825 patent) from 180 (
FIG. 1
) to 360° (
FIGS. 2
,
7
,
10
,
11
, and
14
).
The tube and detector are supported either on two sides (
FIG. 2
) or on a single side only (rest). Where the first embodiment of the '825 patent is limited to rotation of the tube-detector-ensemble around the patient axis (table axis), the second and third embodiments mentioned above basically provide a full 360 degrees of freedom (of course within the limitations given by the patient). That is, by allowing a choice of allowing the rotation axis to rotate the support of the closed circle or ring (
16
) around the horizontal rotation axis (
10
) or even the vertical rotation axis (
11
) allow for 360 degrees of freedom.
Where the first-mentioned embodiment requires additional space-consuming equipment (
5
,
14
,
13
,
15
), solutions
2
and
3
(at least to a certain extent) do not require significant additional equipment. Hence, in fluoroscopic mode, the systems are almost equal to a fluoroscopic-only system from an applicational (functional) point of view. The major drawback of all solutions suggested taught by the '825 patent is the need for rebuilding the system when switching between fluoroscopic and CT mode, and vice versa.
OBJECTS AND SUMMARY OF THE PRESENT INVENTION
Accordingly, it would be desirable for those skilled in the art to realize a C-arm type X-ray system in which a second C-arm element is available for closing the gap in the primary or support C-arm to form a closed ring which overcomes the shortcomings of prior art C-arm X-ray systems, e.g., the '825 patent.
It is therefore an object of the present invention to provide a C-arm X-ray system which supports full volume imaging capabilities with the full flexibility required for interventional procedures without a need to rebuild the system when switching between fluoroscopic and CT modes of operation.
It is another object of the invention to provide a C-arm X-ray system in which an inner “C” of a C-arm mechanism may be enabled and guided by an outer “C” to allow for 360 degree rotation of oppositely disposed X-ray source and X-ray detector mounted on the inner C-arm of the C-arm mechanism. The construction allows operation without the need for a conventional rigid C-arm support, such as that described in the prior art '825 patent.
It must be noted that the inner “C” is never fixed to the support “C”, even when at rest. The use of the terms “stable”, “closed ring” etc. are not meant to imply that the inner C-arm is affixed to the support C-arm. That is, the two “C's” themselves possess the possibility to perform a 360° rotation without the need to construct an auxiliary closed ring beforehand.
It is another object of the invention to provide a C-arm X-ray system that can provide a simple and elegant method of obtaining X-ray projections of a patient from any direction without having to move the patient.
It is another object of the invention to provide a C-arm X-ray system that can provide a simple and elegant method of switching between CT and fluoroscopic applications (e.g., angiographic), without moving the patient from one device to another.
It is another object of the invention to provide a C-arm X-ray system which provides a simple and elegant method of switching between CT and fluoroscopic applications (e.g., angiographic), while maintaining the patient in a common frame of reference (coordinate system) relative to a gantry (comprising the system). Consequently, acquisition of data from both applications allows the combined data to realize additional, previously unavailable diagnostic information, as well as easy patient access during an interventional procedure.
It is another object of the invention to provide a C-arm X-ray system in which a first support C-arm (e.g., 210 degree arc length) including an inner C-arm (e.g., at least 150 degrees of arc length) which inner C-arm may be automatically extended to close the gap in the support c-arm and allow an x-ray source and oppositely disposed x-ray receiver to rotate a full 360 degrees.
The arc length of the support “C” determines the size of the gap size (360°-arc length of support “C”) and hence the patient accessibility. It must be 180° plus ½ overlap with the inner “C”. The inner “C” must have at least 180°, at most the same arc length as the support “C”, else the gap size would decrease. In order to make the construction as rigid and stable as possible, the inner “C” should have its maximum arc length. Both arc lengths should be the same and a compromise has to be made between stability and patie

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