Device and method for radiographic and nuclear imaging of an object

Abstract

A method and device, e.g. a C-arm device, for radiographic and nuclear imaging of an object by means of x-ray and gamma emission imaging. The device comprises a support installation with opposed first and second support members, wherein an x-ray source is mounted on the first support member and an x-ray detector on the second support member. The first support member is additionally provided with at least two gamma cameras that are each located adjacent the x-ray source. Each of said at least two gamma cameras comprising a collimator with one or more collimator openings and a gamma radiation detector. Each of the at least two gamma cameras has an associated field of view. The fields of view of the gamma cameras overlap partly, said overlap defining a focus volume that is seen by the at least two gamma cameras. The focus volume is located between the x-ray source and the x-ray detector so that the x-ray beam passes through the focus volume and the focus volume F is seen by the x-ray detector. The x-ray source, x-ray detector, and gamma cameras are maintained in a stationary acquisition position during x-ray and gamma image data acquisition of x-ray and gamma radiation images respectively, which images are fused into a fused image.

Claims

1. A method for radiographic and nuclear imaging an object, wherein use is made of a C-arm device for radiographic and nuclear imaging of an object by means of x-ray imaging and gamma emission imaging, said C-arm device comprising: a C-arm with opposed first and second free end segments, an x-ray source mounted on said first free end segment and adapted to emit an x-ray beam in an x-ray beam direction, an x-ray detector mounted on said second free end segment and adapted to image onto said x-ray detector the x-ray beam emitted by said x-ray source in said beam direction, wherein the first free end segment of the C-arm is additionally provided with at least two gamma cameras that are each located adjacent the x-ray source, wherein each of said at least two gamma cameras comprises a collimator with one or more collimator openings and each of said at least two gamma cameras further comprises a gamma radiation detector, wherein each of said at least two gamma cameras has an associated field of view, wherein the fields of view of said at least two gamma cameras overlap partly, said overlap defining a focus volume that is seen by said at least two gamma cameras, the focus volume being located between the x-ray source and the x-ray detector so that said x-ray beam passes through the focus volume and the focus volume is seen by the x-ray detector, wherein the C-arm device comprises a computerized image processing unit linked to the x-ray detector and linked to said at least two gamma cameras, the imaging processing unit being programmed to reconstruct a gamma camera image and being adapted to fuse said gamma camera image with an x-ray image obtained with the x-ray detector into a fused image, wherein the C-arm device comprises a display adapted to display an x-ray image, a gamma radiation image, and/or a fused x-ray and gamma radiation image, wherein the C-arm is adapted to provide a stationary acquisition position of the x-ray source, x-ray detector, and gamma cameras, during x-ray and gamma image data acquisition of x-ray and gamma radiation images respectively, that are fused into a fused image, and wherein the x-ray source, x-ray detector, and gamma cameras are maintained in a stationary acquisition position during x-ray and gamma image data acquisition of x-ray and gamma radiation images respectively, which images are fused into a fused image.

2. The method according to claim 1, wherein acquisition of the gamma radiation image is performed simultaneous with the acquisition of the x-ray image while x-ray source, x-ray detector, and gamma cameras are held in said stationary acquisition position.

3. The method according to claim 1, wherein the x-ray source is positioned generally between said at least two gamma cameras.

4. The method according to claim 3, wherein four gamma cameras are provided on the first free end segment, arranged in two pairs of gamma cameras at opposite sides of the x-ray source.

5. The method according to claim 1, wherein each gamma camera has a pinhole collimator with one or more pinholes.

6. The method according to claim 5, wherein each gamma camera has a conical radiation shield with a wide base end near the detector and with a narrow apex remote from the detector, the apex being provided with a one or more pinholes.

7. The method according to claim 1, wherein each gamma camera has a slant angle collimator with multiple collimator openings arranged at an angle relative to the detector.

8. The method according to claim 1, wherein the C-arm device is adapted such that the x-ray detector is solely dedicated to x-ray image acquisition.

9. A C-arm device comprising: a C-arm having opposed first and second free end segments, a C-arm support structure connected to said C-arm intermediate said first and second free end segments, an x-ray source mounted on said first free end segment of the C-arm and adapted to emit an x-ray beam in an x-ray beam direction, and an x-ray detector mounted on said second free end segment of the C-arm, so that an x-ray beam emitted by said x-ray source in said beam direction is imaged onto said x-ray detector, wherein the first free end segment of the C-arm is additionally provided with at least two gamma cameras that are each located adjacent the x-ray source, each of said at least two gamma cameras comprising a collimator with one or more collimator openings and each of said at least two gamma cameras further comprising a gamma radiation detector, each of said at least two gamma cameras having an associated field of view, the fields of view of said at least two gamma cameras overlapping partly, said overlap defining a focus volume that is seen by said at least two gamma cameras, the focus volume being located between the x-ray source and the x-ray detector so that said x-ray beam passes through the focus volume and the focus volume is seen by the x-ray detector.

10. A gamma camera assembly adapted to be mounted on a first free end segment of a C-arm of a C-arm device, which C-arm is provided with an x-ray source on the first free end segment and with an x-ray detector on an opposed second free end segment, which assembly comprises at least two gamma cameras that are arranged to be each located adjacent the x-ray source, each of said at least two gamma cameras comprising a collimator with one or more collimator opening and further comprising a gamma radiation detector, each of said at least two gamma cameras having an associated field of view, the fields of view of said at least two gamma cameras overlapping partly, said overlap defining a focus volume that is seen by said at least two gamma cameras, the focus volume being located between the x-ray source and the x-ray detector so that said x-ray beam passes through the focus volume and the focus volume is seen by the x-ray detector of the C-arm device.

11. A method for the conversion of a pre-assembled x-ray dedicated C-arm device into a dual mode imaging device, said device comprising: a C-arm having opposed first and second free end segments, a C-arm support structure connected to said C-arm, an x-ray source mounted on said first free end segment of the C-arm, an x-ray detector mounted on said second free end segment of the C-arm, so that an x-ray beam emitted by said x-ray source in a beam direction is imaged onto said x-ray detector, the x-ray detector being solely dedicated to x-ray detection and lacking gamma radiation detection capability, wherein the method comprises mounting onto the first free end segment of said C-arm, onto which the x-ray source has been pre-mounted, an assembly of at least two gamma cameras so that they are each located adjacent the x-ray source, each of said at least two gamma cameras comprising a collimator with one or more collimator openings and further comprising a gamma radiation detector, each of said at least two gamma cameras having an associated field of view, the fields of view of said at least two gamma cameras overlapping partly, said overlap defining a focus volume that is seen by said at least two gamma cameras, the focus volume being located between the x-ray source and the x-ray detector so that said x-ray beam passes through the focus volume and the focus volume is seen by the x-ray detector.

12. The method according to claim 2, wherein said gamma radiation image and x-ray image are acquisitioned within at most 1 second.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows in perspective view, schematically, an example of a device according to the invention for radiographic and nuclear imaging of an object by means of x-ray and gamma emission imaging, e.g. of a patient,

(3) FIG. 2 shows schematically, in a cross-sectional view on the free end segments of the C-arm, the device of FIG. 1, a part of a patient, an a patient support table,

(4) FIG. 3 shows diagrammatically the arrangement of relevant parts of the device in a view according to FIG. 2,

(5) FIG. 4a shows the device of FIG. 1 with conical x-ray beam,

(6) FIG. 4b shows the device of FIG. 1 with the fields of view of the gamma cameras,

(7) FIG. 5 shows schematically, in a view corresponding to FIG. 3, an alternative device using slant angle collimator type cameras,

(8) FIG. 6 shows schematically, in a view corresponding to FIG. 4, an alternative arrangement of the gamma cameras,

(9) FIG. 7 shows schematically, in a view corresponding to FIG. 3, an alternative device using parallel hole collimator type cameras,

(10) FIG. 8 shows schematically another example of a device according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(11) With reference to FIGS. 1-4 an exemplary embodiment of a device 1 for radiographic and nuclear imaging of a patient or other object by means of x-ray and gamma emission imaging will be discussed. The FIGS. 1 and 4 show an operator of the device.

(12) The device 1 is a C-arm device comprising a C-arm 2 having a first free end segment 3, a second free end segment 4 opposite from the segment 3, and an intermediate segment 5 that interconnects the first and second free end segments 3, 4. Between the segments 3 and 4 there is an opening space allowing e.g. to place the device in lateral direction over a patient table 6 upon which a patient 7 is lying (see FIG. 2). Here, as is common and preferred in C-arm devices, the intermediate segment is an arctuate segment of uniform radius.

(13) The device 1 further comprises a C-arm support structure 10 that is connected to said C-arm, here between said first and second free end segments, here to the arctuate intermediate segment 5. As is preferred, the support structure allows to rotate the C-arm about an axis that is perpendicular to the plane of the C-arm as a connector member 11 that engages onto the C-arm allows the arctuate segment to slide there along over a limited angular range, the motion being indicated with arrow A in FIG. 1.

(14) Possibly, and preferably, the structure 10 also defines an axis of rotation of the C-arm that lies in the plane of the C-arm, preferably a horizontal axis defined by to the support structure 10, here indicated as axis B.

(15) The support structure 10 can be embodied as a wheeled structure so as to allow for travel over a floor, but other embodiments are also possible, e.g. rail mounted, ceiling mounted, wall mounted, fixed mounting on a floor, etc.

(16) An x-ray source 15 is mounted on the first free end segment 3 of the C-arm 2. Commonly this x-ray source will include an x-ray tube, and possibly a shutter device allowing to interrupt the x-ray beam emitted by the x-ray source.

(17) An x-ray detector 20, here as is preferred an x-ray detector dedicated to x-ray, is mounted on said second free end segment of the C-arm, so that an x-ray beam emitted by the x-ray source in a beam direction is imaged onto the x-ray detector 20.

(18) As can be seen in the FIGS. 1-4 the first free end segment 3 of the C-arm 2 is additionally provided with at least two gamma cameras 30, 31 that are each located adjacent the x-ray source 15 with the x-ray source 15 positioned between the at least two gamma cameras 31, 32.

(19) In this example, as is preferred, four gamma cameras 30, 31, 32, 33, are provided on the first free end segment 3 of the C-arm 2, arranged two pairs of gamma cameras at opposite sides of the x-ray source 15. Here the arrangement is a in square with the x-ray source in the center, but other spatial arrangements, possibly with another number of gamma cameras are also possible.

(20) Each of the gamma cameras 30-33 has a collimator 30a-33a with one or more collimator openings and each of the gamma cameras 30-33 further comprises a gamma radiation detector 30b-33b.

(21) Each gamma camera 30-33 has an associated field of view, which is schematically shown in FIGS. 2, 3 and 4b.

(22) As can be seen in FIG. 2 the x-ray source 15 lies fully outside the field of view of each of the gamma cameras 30-33.

(23) The fields of view the overlapping partly, in this example as is preferred, each field of view has some overlap with all other fields of view of the other gamma cameras. The overlap defines a focus volume F that is seen by at least two, and here as is preferred all, gamma cameras 30-33.

(24) The focus volume F is located between the x-ray source 15 and the x-ray detector 20 so that the x-ray beam passes through the focus volume F and the focus volume F is seen by the x-ray detector.

(25) As explained above this arrangement allows to construct a gamma emission radiation image that is in a plane parallel to the imaging plane of the x-ray system, which is perpendicular to the beam direction of the x-ray beam.

(26) As is preferred, the x-ray beam is a conical beam (see FIG. 4a), but other beam embodiments, e.g. a fanned beam, are also possible.

(27) In the FIGS. 1-4 it is illustrated that each gamma camera 30-33 has a conical radiation shield 30c-33c with a wide base end near the detector 30ba-33b and with a narrow apex remote from the detector. The apex is embodied as collimator with one or more collimator openings, here is preferred with a single pinhole or a group or cluster of pinholes.

(28) FIG. 5 illustrates an alternative version wherein the gamma cameras 30′-33′ are not provided with the conical shield and pinhole collimator, but are provided with a slant angle collimator 33a′ with multiple collimator openings arranged at an angle relative to the detector 30b′. This also leads to each camera having its own field of view and the fields of view overlapping partly in a focus volume F that is intersected by the x-ray beam.

(29) The device comprises computerized image processing unit 40 that linked to the x-ray detector 15 and to the gamma cameras 30-33. This imaging processing unit 40 is programmed to reconstruct a gamma camera image in a plane transverse to the x-ray beam direction on the basis of the information received from the detectors 30b-33b.

(30) As is preferred unit is programmed to fuse an x-ray image with the image obtained by means of the gamma cameras.

(31) The device may be embodied to alternate the x-ray imaging with gamma emission imaging, e.g. by means of a pulsed x-ray beam and the gamma imaging being effected in the pauses between x-ray pulses. Other approaches are also possible.

(32) Preferably the device 1 comprises a display 45 adapted to display an x-ray image, a gamma radiation image, and/or a fused x-ray and gamma radiation image.

(33) The skilled person will appreciate that the cameras 30-33 can be embodied as a gamma camera assembly that is adapted to be mounted on the first free end segment 3 of a C-arm 2 that is provided with an x-ray source 15, e.g. in view of retrofitting such an assembly on an existing x-ray C-arm device in order to achieve dual mode imaging capability.

(34) FIG. 6 illustrates an alternative wherein the cameras 30-33 are mounted higher relative to the x-ray source 15 than in FIG. 1. The shields 30c-33c extend upward beyond the top end of the x-ray source 15. As in FIGS. 1-4 and in FIG. 5, the x-ray source 15 is located between the cameras 30-33 and the x-ray beam (which here also is conical) is not interfering with the shields 30c-33c of the gamma cameras. This arrangement achieves the effect that the gamma cameras 30-33 can be closer to the patient 7 yet at the expense of reduction of the free space between the opposed end segments of the C-arm device.

(35) FIG. 7 illustrates a further alternative version wherein the gamma cameras 30″-31″ are provided with a parallel hole collimator 30a″, 31a″ with multiple collimator openings arranged normal to the planar incident face of the underlying detector 30b″, 31b″. This also leads to each camera having its own field of view and the fields of view overlapping partly in a focus volume F that is intersected by the x-ray beam. As can be seen the detectors 30b″, 31b″ are arranged at an incline relative to a plane that is normal to the x-ray beam direction such that the incident planes of different gamma camera detectors delimit between them an angle less than 180°.

(36) FIG. 8 illustrates schematically an embodiment that allows the operator to adjust and set the stationary acquisition position of the x-ray equipment and the gamma cameras, e.g. dependent on the object to be examined, e.g. the patient.

(37) It is illustrated that the gamma cameras 30′″ and 31′″ are movably arranged on the first support member 3 to allow for setting of a desired static acquisition position of the gamma cameras relative to the object. The gamma cameras are mounted on the first support member in a translatable manner in a direction generally parallel to the x-ray beam direction, e.g. on a telescopic arrangement as indicated with arrows. In this example also the x-ray source 15 is movable mounted on the support member 3, also in a translatable manner in a direction generally parallel to the x-ray beam direction, e.g. on a telescopic arrangement as indicated with an arrow. In this example it is illustrated that, if desired, also the x-ray detector 20 can be movably mounted on the second support member, e.g. in a translatable manner in a direction generally parallel to the x-ray beam direction, e.g. on a telescopic arrangement as indicated with an arrow.

(38) As explained, the adjustability of the static acquisition position of the gamma cameras and/or of the x-ray source, and/or of the x-ray detector, e.g. in translatory manner towards and away from the opposite support member of the installation, may be used to achieve an optimal position relative to the object to be imaged.

(39) It is noted that the device of FIG. 8 could, for example, be a C-arm device with the first and second support members 3, 4 interconnected by a C-arm. In another embodiment, the first and second support members 3, 4, could for example be vertical support columns (so that the FIG. 8 is a top view), e.g. for a patient standing in the space between the x-ray source and detector.

(40) FIG. 8 also illustrates the provision of one or more gamma cameras 30′″ and 31′″ that allows for adjustment of the distance between the one or more pinholes of the collimator 30a′″ and 31a′″ on the one hand and the detector 30b′″ and 31b′″ on the other hand. In this example the collimator shield 30c′″ and 31c′″ is telescopic to allow for said adjustment, e.g. with a motor drive to effect the telescopic motion as depicted with arrows. It will be appreciated that the possibility for adjustment of the distance between the one or more pinholes and the detector can also be employed in devices wherein the gamma cameras and/or x-ray source and/or x-ray detector are stationary mounted on their respective support member. It will further be appreciated that the distance adjustment possibility may allow for variation of the overlap of the fields of view of the gamma cameras, or simply to provide for a retracted mode of the gamma cameras for situations wherein the gamma cameras are not used, e.g. to create maximum space for the object and object support, e.g. a patient support table.