DEVICE AND METHOD FOR SIMULTANEOUS X-RAY AND GAMMA PHOTON IMAGING WITH A STACKED DETECTOR

Abstract

A dual mode radiation detector comprising an x-ray detector layer to convert incident x-ray radiation into x-ray electrical data, said x-ray detector forming an incident face of said dual mode radiation detector, a collimator disposed below the x-ray detector layer, and a gamma photon detector layer disposed below the collimator to convert incident gamma photons into gamma photon electrical data.

Claims

1. A dual mode radiation detector comprising: an x-ray detector layer to convert incident x-ray radiation into x-ray electrical data, said x-ray detector layer forming an incident face of said dual mode radiation detector; a collimator disposed below the x-ray detector layer; and a gamma photon detector layer disposed below the collimator to convert incident gamma photons into gamma photon electrical data.

2. A dual mode radiation detector according to claim 1, wherein the x-ray detector layer, collimator and gamma photon detector layer are stacked directly on top of each other.

3. A dual mode radiation detector according to claim 1, wherein an x-ray filter layer is arranged between the x-ray detector layer and the collimator, e.g. wherein the x-ray detector layer, x-ray filter layer, collimator, and gamma photon detector layer are stacked directly on top of each other.

4. A dual mode radiation detector according to claim 1, wherein the frontal area of the collimator and of the gamma photon detector layer each equal that of the incident face of said dual mode radiation detector.

5. A dual mode radiation detector according to claim 1, wherein said collimator is removable and insertable into said dual mode radiation detector.

6. A dual mode radiation detector according to claim 1, wherein the x-ray detector layer is an indirect flat panel detector comprising a scintillator layer and below said scintillator layer a detector array containing photodiodes.

7. A dual mode radiation detector according to claim 1, wherein the collimator and gamma photon detector layer form a gamma camera, said gamma camera comprising the collimator, a scintillator layer and below said scintillator layer a photomultiplier layer.

8. A dual mode radiation detector according to claim 1, wherein the collimator is a cone beam collimator.

9. A dual mode radiation detector according to claim 7, wherein the collimator is a parallel hole collimator.

10. A dual mode radiation detector according to claim 1, wherein the collimator disposed between the x-ray detector layer and gamma photon detector layer is the only collimator of the dual mode radiation detector and wherein the incident face is fully exposed to radiation impinging on said dual mode radiation detector.

11. A dual mode radiation detector according to claim 9, further comprising an anti-scatter grid provided in front of the x-ray detector to reduce the amount of scattered x-ray radiation incident upon the x-ray detector layer.

12. A dual mode radiation detector according to claim 11, wherein said anti-scatter grid is removable from said dual mode radiation detector.

13. A dual mode radiation detector according to claim 11, wherein said anti-scatter grid is configured to transmit at least part of the gamma photons and wherein said anti-scatter grid is adapted to remain in place in front of the x-ray detector during acquisition of gamma photon electrical data.

14. A dual mode radiation detector according to claim 1, wherein said gamma photon detector layer comprises a scintillator layer with a decay time shorter than that of sodium iodide scintillators with thallium doping, e.g. by using a lutetium yttrium orthosilicate or lanthanum tribromine (LaBr3) scintillation crystal.

15. A dual mode radiation detecting system, comprising a dual mode radiation detector according to claim 1 and an image processing unit, said image processing unit receiving both the x-ray electrical data and gamma photon electrical data from said dual mode radiation detector and said image processing unit adapted to fuse simultaneously acquired x-ray electrical data and gamma photon electrical data into fused images containing both x-ray electrical data and gamma photon electrical data.

16. A dual mode radiation detecting system according to claim 15, wherein the gamma photon electrical data comprises information on the energy of photons incident on the gamma photon detector layer, and said image processing unit is configured to filter out x-ray photons incident on the gamma photon detector layer on the basis of the energy of photons incident on the gamma photon detector layer.

17. A dual mode radiation detecting system according to claim 15, said system configured for simultaneous fluoroscopy and scintigraphy.

18. A dual mode imaging system, comprising a dual mode radiation detector according to claim 14, an image processing unit and an x-ray source, e.g. an x-ray tube, said image processing unit receiving both the x-ray electrical data and gamma photon electrical data from said dual mode radiation detector, wherein said image processing unit is adapted to fuse acquired x-ray electrical data and gamma photon electrical data into fused images containing both x-ray electrical data and gamma photon electrical data.

19. A dual mode imaging system, comprising a dual mode radiation detector according to claim 1, an image processing unit and an x-ray source, e.g. an x-ray tube, said x-ray source having a focal spot, wherein said image processing unit is adapted to receive both the x-ray electrical data and gamma photon electrical data from said dual mode radiation detector, wherein said the collimator of said dual mode radiation detector is cone beam collimator having a focal spot that is offset from the focal spot of the x-ray source.

20. A dual mode imaging system, comprising a dual mode radiation detector according to claim 1, an image processing unit and an x-ray source, e.g. an x-ray tube, said image processing unit receiving both the x-ray electrical data and gamma photon electrical data from said dual mode radiation detector, said x-ray source adapted to emit pulses of x-ray radiation, wherein said gamma photon detector layer detects photons in between said pulses of x-ray radiation and wherein said image processing unit is adapted to fuse acquired x-ray electrical data and gamma photon electrical data, wherein said x-ray electrical data is acquired during an x-ray pulse and said gamma photon electrical data is acquired before or after said x-ray pulse so that both x-ray electrical data and gamma photon electrical data are acquired within a time interval of 0.5 second, into fused images containing both x-ray electrical data and gamma photon electrical data.

21. A dual mode imaging system according to claim 20, further comprising a support installation supporting said x-ray source and said dual mode radiation detector, said support installation adapted to provide a stationary acquisition position of the x-ray source and dual mode radiation detector, and wherein the x-ray electrical data and gamma photon electrical data fused into said fused images are obtained with the x-ray source and dual mode radiation detector in said stationary acquisition position.

22. A dual mode imaging system according to claim 21, wherein said support installation is a C-arm device, said device comprising: a C-arm having opposed first and second free segments, a C-arm support structure connected to said C-arm intermediate said first and second free end segments, wherein said x-ray source is supported by said first free end segment of the C-arm and adapted to emit an x-ray beam in an x-ray beam direction, and wherein said dual mode radiation detector is supported by said second free end segment, so that an x-ray beam emitted by said x-ray source in said beam direction is imaged onto said dual mode radiation detector.

23. A C-arm dual mode radiation detecting device, said device comprising: a C-arm having opposed first and second free 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 a dual mode radiation detector according to claim 14, said dual mode radiation detector mounted on said second free end segment, so that an x-ray beam emitted by said x-ray source in said beam direction is imaged onto said dual mode radiation detector

24. A dual mode imaging system comprising a dual mode radiation detector according to claim 14, an image processing unit, and an x-ray source, e.g. an x-ray tube, said image processing unit being adapted to receive both the x-ray electrical data and gamma photon electrical data from said dual mode radiation detector, wherein said system further comprises a rotating gantry which defines a subject receiving aperture, the rotating gantry being adapted to rotate about the subject receiving aperture about an axis of rotation; the x-ray source being mounted to the rotating gantry for rotation therewith, a detector head mounted to the rotating gantry for rotation therewith, the detector head being mounted opposite the x-ray source, the detector head comprising said dual mode radiation detector to receive x-rays from the x-ray source as well as to receive gamma photon radiation from a subject in said subject receiving aperture.

25. Method for simultaneous x-ray and nuclear imaging comprising the steps of: providing an object containing a radioactive isotope that emits gamma photons; providing an x-ray source adapted to emit x-ray radiation towards said examination region; providing one or more dual mode radiation detectors according to claim 24, said radiation detectors adapted to detect x-ray radiation emitted by said x-ray source, e.g. x-ray radiation transmitted through said object, and to detect gamma photons emitted by said radioactive isotope within said object; acquiring simultaneously x-ray electrical data and gamma photon electrical data with said dual mode radiation detector; processing said x-ray electrical data and gamma photon electrical data to reconstruct x-ray images and gamma emission images, respectively; and fusing x-ray images and gamma emission images of simultaneously acquired x-ray electrical data and gamma photon electrical data into fused x-ray and gamma photon images.

26. Method according to claim 25, wherein said x-ray source is operated to emit pulses of x-ray radiation, e.g. pulses with a duration of between 1 and 10 ms, and wherein x-ray electrical data is acquired during an x-ray pulse and gamma photon electrical data is acquired before and/or after said x-ray pulse, e.g. so that both x-ray electrical data and gamma photon electrical data for a fused image are acquired within a time interval of at 25 most 0.5 second.

27. Method according to claim 24, wherein said x-ray electrical data and gamma photon electrical data fused into fused images are acquired with said x-ray source and said dual mode radiation detector in a stationary acquisition position.

28. Method according to claim 24, wherein the x-ray imaging is fluoroscopic imaging and the nuclear imaging is scintigraphic imaging.

Description

[0074] The invention will now be discussed with reference to the drawings. In the drawings:

[0075] FIG. 1 shows a side view of a dual mode radiation detector according to the invention,

[0076] FIG. 2 shows a side of a dual mode radiation detecting system according to the invention,

[0077] FIG. 3 shows a side view of another dual mode radiation detector according to the invention.

[0078] The elements of these drawings are not scaled, that is, no information can be found in the relative dimensions of elements of these drawing.

[0079] With reference to the drawings embodiments and optional features of the dual mode radiation detector will be described.

[0080] FIG. 1 shows a dual mode radiation detector 1 comprising an x-ray detector layer 11. Said x-ray detector 11 forms the incident face of said dual mode radiation detector. A collimator 12 is disposed below said x-ray detector 11 and a gamma photon detector layer is disposed below said collimator 12.

[0081] In the shown embodiment collimator 12 is a parallel hole collimator. However, the use of other types of collimators, such as a cone beam collimator, is also envisioned as is discussed with reference to FIG. 3.

[0082] FIG. 2 shows a dual mode radiation detecting system 2. The dual mode radiation detecting system comprises 2 a dual mode radiation detector 1 according to the invention, said dual mode radiation detector comprising an x-ray detector layer 11, a collimator 12 and an gamma photon detector 13 layer in that order.

[0083] Said x-ray detector layer 11 outputs x-ray electrical data 41 comprising information e.g. on the time, location and energy associated with detections. Furthermore, gamma photon detector layer 13 outputs gamma photon electrical data 42 comprising information e.g. on the time, location and energy associated with detections.

[0084] Furthermore, FIG. 2 shows an x-ray source 21, e.g. an x-ray tube, that emits x-ray radiation 22 in the direction of a patient 31. Said x-ray radiation is partly transmitted through said patient, e.g. rays 22 and 23, and impinges upon the detector 1 at the incident face thereof. Said radiation is partly absorbed in x-ray detector 11, e.g. ray 22, and partly transmitted by said x-ray detector and subsequently absorbed by the collimator 12. Alternatively, but not shown, rays may be transmitted by the x-ray detector and collimator, and may be absorbed by the gamma photon detector.

[0085] A radioactive isotope is present in a region 32 of the patient 31. Said isotope emits gamma photons, e.g. photons 33 and 34. Said photons may be transmitted by the x-ray detector. Subsequently they may be pass the collimator, e.g. photon 34, and may be absorbed by the gamma photon detector. If their direction of propagation differs from the alignment of the collimator apertures, they may also be absorbed by said collimator as is here the case for photon 33.

[0086] Said dual mode radiation detecting system 2 further comprises a image processing unit 51 that receives the x-ray electrical signal 41 and gamma photon electrical 42. Said image processing unit constructs based on the x-ray electrical signal 41 an x-ray image and reconstructs, based on the gamma photon electrical data 41 and considering the characteristics of the collimator 12, an gamma photon emission image.

[0087] Subsequently, the x-ray transmission image and gamma photon from simultaneously detected x-ray radiation and gamma photon radiation can be fused into a single fused image 62 and said fused image displayed on a display 61.

[0088] FIG. 3 shows a dual mode radiation detector 1 composed of components that are stacked directly onto one another.

[0089] An x-ray detector layer 11 forms the incident face of the dual mode radiation detector.

[0090] Below said x-ray detector layer, as is optional, there is an x-ray filter layer 16, e.g. made of or comprising Tin (Sn). The layer 16 is preferably designed to filter out x-rays whilst being transparent to gamma photons.

[0091] A collimator 12 is disposed below the x-ray detector 11, and here also below the x-ray filter layer.

[0092] As schematically indicated, and as preferred, the collimator is a cone beam collimator having a focal spot FP.

[0093] Below the collimator 12 a gamma photon detector layer 13 is disposed.

[0094] As explained it may be advantageous to arrange and/or embody the detector 1 with cone beam collimator 12 such that is focal spot FP is offset, e.g. laterally, from the focal spot of the x-ray source. This reduces/avoids penetration of x-ray through the collimator, which may be advantageous for the operation of the detector layer 13.

[0095] For example the radiation detector comprises a support structure, e.g. a skeletal frame, wherein these components are stacked and secured, e.g. removable from the frame, e.g. allowing to exchange one component for an alternative version of said component and/or allowing to arrange or dispense with the filter layer 16.