X-ray system with modular double-layer detector

Abstract

The invention relates to a detection system for an X-ray imaging system. The detection system includes a first detector and a second detector, each detector including a detector region and configured to detect X-ray radiation emitted by an X-ray source of an X-ray imaging system incident on a respective detection region. The detection system is configured to adjust a position of at least one of the first detector and the second detector relative to the other of the first detector and the second detector. The first detection zone of the first detector and the second detection zone of the second detector may be at least partially positioned one after the other with respect to a direction of X-ray radiation emitted from an X-ray source of the X-ray imaging system.

Description

TECHNICAL FIELD

[0001] The present invention relates to a detection system for an X-ray imaging system, an X-ray imaging system comprising the detection system and a method of imaging an object with the X-ray imaging system. BACKGROUND

[0002] Imaging in diagnostic or interventional X-ray imaging zones (DXR / IXR) is usually mainly limited to the detection of the linear attenuation coefficient at the average energy of the X-ray beam. However, in the field of computed tomography, there is a trend to move to spectral imaging using various different methods like dual source imaging, dual layer detector, fast kVp switching or even photon counting with energy discrimination. Spectral imaging allows to distinguish between the two contributions to the attenuation, namely photoelectric absorption and Compton scattering. This eventually allows to separate soft tissue from iodine in the image, for example, enabling an improved or simplified diagnosis in some tasks. Dual layer detectors can be used for spectral imaging, where two fixed layers are used for energy separation, which detects low energy photons on the top layer and high energy photons on the bottom layer. However, since spectral imaging is currently only a special application in DXR and IXR, large dual layer detectors are too expensive.

[0003] Therefore, the inventors of the present invention have found that it would be advantageous to have an improved detection system for an X-ray imaging system which at least partially solves these problems and allows for spectral X-ray imaging while reducing costs. SUMMARY

[0004] It is an object of the present invention to provide an improved modular detection system for an X-ray imaging system which allows for a flexible adaptation of the detection zone and spectral X-ray imaging on at least parts of the active detection zone.

[0005] The objects of the present invention are solved by the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims.

[0006] The described embodiments similarly relate to a detection system for an X-ray imaging system, an X-ray imaging system comprising the detection system and a method of imaging an object with the X-ray imaging system. The further described embodiments can be combined in any possible way. Synergistic effects can result from different combinations of embodiments, although they can not have been described in detail.

[0007] Furthermore, it should be noted that all embodiments of the present invention with respect to the method can be performed in the order of the described steps, however, this is not the only and necessary order of the steps of the method. The method presented herein can be performed in another order of the disclosed steps without leaving the scope of the respective method embodiment, unless explicitly mentioned to the contrary hereinafter.

[0008] According to a first aspect of the present application, a detection system for an X-ray imaging system is provided. The detection system comprises a first detector configured to detect X-ray radiation of the X-ray imaging system incident on a first detection area of the first detector and a second detector configured to detect X-ray radiation of the X-ray imaging system incident on a second detection area of the second detector. The detection system is configured to adjust a position of at least one of the first detector and the second detector relative to the other one of the first detector and the second detector and to position the first detection area and the second detection area at least partially one after the other relative to a direction of the X-ray radiation incident on the first detection area of the first detector and the second detection area of the second detector.

[0009] Thus, the present application proposes a modular DXR or IXR detection system comprising a first detector adapted to be adjacent to an object being scanned and a second detector at least partially located behind the first detector and at least partially shielded from the object scanned by the first detector. Both detectors detect X-ray radiation generated by a generator or source of the X-ray imaging system, which X-ray radiation passes through the object and is incident on the detection system. The second detector can be repositioned relative to the first detector. Thus, a detector configuration with two at least partially overlapping detector layers is provided, wherein both detector layers detect signals for forming a final X-ray image and wherein both detector layers can be repositioned relative to each other to adapt the detection area and / or properties of the detectors.

[0010] For example, for an energy separation mode, a second detector, which can be smaller than the first detector, can be placed at a region of interest to provide spectral imaging in this region, while the first detector acquires information for a full body image. Preferably, the first detector and the second detector can differ in terms of pixel size, spatial resolution and / or energy sensitivity, etc. Thus, advantageously, the detection areas of the two detectors, which have been slid behind each other, are used for image reconstruction, wherein one detector is shielded from the object being scanned by the other detector.

[0011] In embodiments of the present application, the first detection area and the second detection area are arranged substantially parallel or concentric to each other. This ensures that radiation emitted from the X-ray source penetrates both the first detection area and the second detection area and is thus detected by both detectors. The detection areas can have planar or curved surfaces. In case of curved surfaces, the detectors can be arranged concentrically.

[0012] In embodiments of the application, the second detector is configured to be translated relative to the first detector in a direction parallel to a surface of the first detection area of the first detector and / or in a direction perpendicular to a surface of the first detection area of the first detector. Optionally, at least one of the detectors can be a curved main detector, and the smaller detector can follow the curved geometry of the main detector when being translated. In this case, it can be necessary to tilt the smaller detector to adjust the alignment with the main detector.

[0013] In embodiments of the application, the second detection area of the second detector has a different size than the first detection area of the first detector.

[0014] In embodiments of the application, the spatial resolution of the second detector is different than the spatial resolution of the first detector.

[0015] In embodiments of the application, the first detector has a higher transparency with respect to the X-ray radiation incident on the first detection area and the second detection area than the second detector with respect to the X-ray radiation incident on the first detection area and the second detection area.

[0016] In embodiments of the application, the energy sensitivity of the second detector is different than the energy sensitivity of the first detector. Thus, the first detector and the second detector can preferably detect X-rays having different wavelengths.

[0017] In embodiments of the application, the detection system further comprises a processing unit configured to reconstruct an X-ray image based on the X-ray radiation detected by the first detector and the second detector.

[0018] In embodiments of the application, the reconstructed X-ray image comprises a first region and a second region, wherein the first region is reconstructed based on X-ray radiation detected by both the first detector and the second detector, and the second region is reconstructed based on X-ray radiation detected by one of the first detector and the second detector, and at least one image property of the X-ray image is better in the first region than in the second region. Thus, the first region can enable spectral imaging, higher spatial resolution, higher image quality due to less scatter, etc. Optionally, the exact position of the first detector and / or the second detector can be measured, and the position information can be used for the image reconstruction, for example, as the position can vary with time of the scan.

[0019] In embodiments of the application, at least one of the first detector and the second detector comprises an anti-scatter grid.

[0020] According to another aspect of the present application, an X-ray imaging system is provided, comprising a detection system according to any of the preceding embodiments, and an X-ray source.

[0021] In embodiments of the present application, the X-ray imaging system comprises a beam collimator, and the beam collimator is configured to focus the X-ray radiation emitted by the X-ray source to an area covered by the first detection area and the second detection area. An adaptation of the beam collimation with the tube collimator can be necessary to adapt the beam to the detector size and the body region to be imaged.

[0022] In embodiments of the present application, the X-ray imaging system further comprises an irradiation indicator configured to visualize an anatomical region of the object to be imaged, the anatomical region being located between the X-ray source and at least one of the first detection area and the second detection area. For example, a laser beam can be used to indicate the boundaries of the detection area on the object.

[0023] In embodiments of the present application, the irradiation indicator is configured to visualize the anatomical region located between the X-ray source and the first detection area separately from the anatomical region located between the X-ray source and the second detection area.

[0024] According to another aspect of the present application, a method of imaging an object with an X-ray imaging system according to any of the preceding embodiments is provided. The method comprises the steps of providing the X-ray imaging system; positioning the object between the X-ray source and the detection system; adjusting the position of at least one of the first detector and the second detector of the detection system; and acquiring an image of at least an anatomical region of the object. Preferably, the region of interest of the object is imaged with increased quality and / or different imaging properties.

[0025] Hence, the benefits provided by any of the above-mentioned aspects equally apply to all other aspects, and vice versa.

[0026] In summary, the present application relates to a detection system for an X-ray imaging system. The detection system comprises a first detector and a second detector, each detector comprising a detector area and being configured for detecting X-ray radiation emitted by an X-ray source of the X-ray imaging system incident on the respective detector area. The detection system is configured to adjust the position of at least one of the first detector and the second detector relative to the other one of the first detector and the second detector. The first detection area of the first detector and the second detection area of the second detector can be positioned at least partially one after the other relative to a direction of the X-ray radiation emitted from the X-ray source of the X-ray imaging system.

[0027] One of the advantages of embodiments of the present invention with a flexible geometry configuration of the detection system is that the region of interest of a patient can be imaged with spectral X-ray imaging. Another advantage is that the field of view of the X-ray system, in particular the entire detection area, can be extended by using two partially overlapping detectors. Another advantage is that an adaptation of the spatial resolution of the detection system can be applied, thereby realizing a zoom function of the detection system. Another advantage is that the scattered radiation generated by the first detector reaching the second detector can be reduced if the second detector applies a focused anti-scatter grid.

[0028] These advantages are non-limiting and other advantages can be envisaged in the context of the present application.

[0029] The above aspects and embodiments will become apparent from and will be elucidated with respect to the exemplary embodiments described hereinafter, and with reference to the accompanying drawings. The exemplary embodiments of the present application will be described with reference to the following drawings: BRIEF DESCRIPTION OF DRAWINGS

[0030] Figures 1A-1C A schematic setup of a detection system for an X-ray imaging system according to an embodiment of the present invention is shown.

[0031] Figure 2 A schematic setup of an X-ray imaging system comprising a detection system according to an embodiment of the present invention is shown.

[0032] Figure 3 A block diagram of a method of imaging an object with an X-ray imaging system according to an embodiment of the present invention is shown. LIST OF REFERENCE SIGNS 100 detection system 110 first detector 111 first detection area 120 second detector 121 second detection area 130 processing unit 140 object 200 X-ray imaging system 210 X-ray source 220 X-ray radiation DETAILED DESCRIPTION

[0033] Figures 1A-1C A schematic setup of a detection system 100 for an X-ray imaging system 200 according to an embodiment of the present invention is shown. Different possible geometrical relationships between the two detectors for a diagnostic X-ray imaging system are indicated.

[0034] In Figure 1AIn the first exemplary embodiment shown, a full overlap between the first detection region 111 of the first detector 110 and the second detection region 121 of the second detector 120 is shown. The detection regions of the two detectors are arranged parallel to each other and are configured for detecting X-ray radiation 220 emitted from a radiation source 210 of the X-ray imaging system 200. The X-ray radiation 220 penetrates the first detection region 111 and the second detection region 121 and is detected in both detectors, which is possible due to the at least partial overlap of the respective detection regions 111, 121. The signals of both detectors are used for reconstructing an X-ray image. In this embodiment, at least the second detector 120 is configured such that a position of the second detector 120 relative to the first detector 110 can be adjusted. This repositioning is indicated by the double arrow next to the second detector, which indicates a lateral translation in an x-y direction parallel to the first detection region 111. This allows for selecting a region of interest of the object 140 to be imaged, wherein an overlap region is achieved, in which both detectors detect X-rays penetrating the overlap region. Imaging outside the overlap region is performed with only a single detector, i.e. the first detector 110 in this embodiment.

[0035] In Figure 1B In the second exemplary embodiment shown, a configuration with only a partial overlap between the first detection region 111 and the second detection region 121 is shown. This partial overlap can result from a translation of the second detector 120 to the border of the first detector 110. However, the X-ray radiation 220 still at least partially penetrates both the first detection region 111 and the second detection region 121. In this configuration, the entire region of the field in which X-rays can be detected in the X-ray imaging system can be extended. In addition, an overlap region can be achieved, in which both detectors detect the X-ray radiation 220.

[0036] In Figure 1C In the third exemplary embodiment shown, a configuration of the detection system 100 is shown, in which additionally a distance between the first detector 110 and the second detector 120 in the z-direction can be adjusted. Thus, a movement in the plane of the detectors and perpendicular to this plane is possible. This can have the advantage that the second detector 120 picks up less scattered radiation generated in the first detector 110. In particular, after a certain distance, the scattered radiation detected by the second detector 120 will be smaller, while the directly unscattered high-energy X-ray radiation will still reach the second detector 120.

[0037] It is noted that while the figures depict a case in which the first detector 110 and in particular the first detection region 111 is larger than the second detection region 121 of the second detector 120. However, in other, not shown embodiments, the size of the second detector 120 can exceed the first detector.

[0038] While it can be advantageous to use two detectors with the same properties, the presented concept can be further enhanced by implementing two detectors with different properties. Thus, the following combinations can be considered.

[0039] Transparency: When the two detectors overlap each other, the overlapping part can be used for double detection of X-ray radiation 220 penetrating the overlapping part. Thus, it can be advantageous if the first detector 110 has a higher transparency for the applied radiation than the second detector 120.

[0040] Resolution: It can be advantageous if the first detector 110 has a different spatial resolution than the spatial resolution of the second detector 120. For example, the first detector 110 can be a smaller, higher resolution detector, while the second detector 120 is a larger, lower resolution detector. In such a configuration, a higher resolution image of a region of interest can be achieved in a larger field of view with lower resolution.

[0041] Spectrum: It can be advantageous if the first detector 110 has a different spectral characteristic than the spectral characteristic of the second detector 120. For example, the first detector 110 can be sensitive to X-rays at a given first wavelength, while the second detector 120 is sensitive to X-rays at a given second wavelength. In such a configuration, spectral imaging can be achieved. Preferably, the first detector 110 is more sensitive to low-energy X-rays with a long wavelength, while the second detector 120 is more sensitive to high-energy X-rays with a shorter wavelength.

[0042] In general, any combination of the above-mentioned different properties can be considered. For example, two detectors with different functionalities, like spectral sensitivity and spatial resolution, and a double detection functionality at the overlapping region can be employed. This can result in a higher resolution of the resulting X-ray image at one wavelength and a lower resolution at a second wavelength.

[0043] Preferably, the first detection region 111 and the second detection region 121 are arranged substantially parallel or concentric to each other. This ensures that radiation emitted from the X-ray source 210 penetrates both the first detection region 111 and the second detection region 121 and is thus detected by both detectors. The detection regions can have planar or curved surfaces. In the case of planar surfaces, the detectors can be arranged parallel or at least substantially parallel to each other. In the case of curved surfaces, the detectors can be arranged concentrically.

[0044] Preferably, the second detector 120 is movable such that it can be translated relative to the first detector 110 in a direction parallel and / or perpendicular to the surface of the first detection 111 region of the first detector 120. Optionally, at least one of the detectors can be a curved main detector and the smaller detector can follow the curved geometry of the main detector when being translated. In this case, it can be necessary to tilt the smaller detector to adjust the alignment with the main detector.

[0045] In embodiments of the application, the detection system 100 comprises a processing unit 130 in communication with the first detector 110 and the second detector 120 and generating an X-ray image based on the X-ray radiation 220 detected by the first detector 110 and the second detector 120.

[0046] Preferably, the generated or reconstructed X-ray image comprises a first region and a second region. The first region can be reconstructed based on the X-ray radiation 220 detected by both the first detector and the second detector, while the second region is reconstructed based on the X-ray radiation 220 detected by only one of the first detector and the second detector. Thus, the first region is a region in which the first detection region 111 and the second detection region 121 overlap each other such that at least one image property of the X-ray image can be different, preferably better in the first region than in the second region. Thus, the first region can enable at least one of the following: spectral imaging, higher spatial resolution, higher image quality due to less scatter, etc. Optionally, the exact position of the first detector 110 and / or the second detector 120 can be measured and the position information can be used for e.g. image reconstruction, as the position can vary with time of the X-ray scan.

[0047] Further, at least one of the detectors, preferably the second detector 120, can comprise an anti-scatter grid for suppressing radiation scattered in the first detector 110.

[0048] Figure 2 A schematic setup of an X-ray imaging system 200 comprising a detection system 100 and an X-ray source 210 according to embodiments of the application is shown. A patient is positioned as an object 140 to be imaged between the detection system 100 and the X-ray source 210 of the X-ray imaging system 200. X-ray radiation 220 emitted from the X-ray source 210 penetrates the object 140 as well as both the first detection region 111 of the first detector 110 and the second detection region 121 of the second detector 120. The processing unit 130 is used to read out the information received from both detectors and to generate an X-ray image of the object 140 using the data from both detectors.

[0049] Optionally, the X-ray imaging system 200 can comprise a beam collimator for focusing the X-ray radiation 220 emitted by the X-ray source 210 to the area covered by the first and second detection zones 111, 121. An adaptation of the beam collimation with a tube collimator can be necessary to adapt the beam to the detector size and the body region to be imaged. Furthermore, an irradiation indicator can be used to visualize the anatomical region of the object 140 to be imaged. For example, a laser beam can be used to indicate the boundaries of the detection zones or the shape of the X-ray beam on the object 140. Preferably, the irradiation indicator can visualize the anatomical region between the X-ray source 210 and the first detection zone 111 and the anatomical region between the X-ray source 210 and the second detection zone 121, respectively.

[0050] Thus, the collimator can be used to geometrically limit the X-ray beam such that only the relevant anatomical region of the patient is irradiated. This is usually done by optical means that project visible light in the beam, allowing the operator to properly adjust the collimator. With a detection system having two zones with different characteristics, it is desirable to indicate to the operator the zones in which spectral and conventional imaging is possible, respectively. Thus, one possible option can be to use a beam indicator that visualizes the position of the collimator leaves of the beam collimator by four laser lines. In the current case, the position of the detector edges of the two detectors can be visualized by four additional laser lines, preferably using a different color than the first four laser lines.

[0051] Optionally, the second detector 120 can be placed on the same arc at an angle of approximately 59° with respect to the central axis of the beam to capture maximum scatter information, as the scatter peak is at the above-mentioned angle. The properly reconstructed volume from the second detector 120 can be used as a scatter mask, which in turn can be applied to the main volume acquired by the first detector 110 in order to remove scatter artifacts. The above-mentioned arrangement of the second detector 120 with an angle of 59° with respect to the central beam can also be used to supplement the main volume with scatter information.

[0052] Furthermore, in case the first and second detectors 110, 120 differ in pixel size, or even if they have the same spatial resolution but are intentionally misaligned, the images corresponding to the overlapping region can be reconstructed at a higher resolution than would have been allowed by the image reconstruction using the super-resolution technique of the first or second detector 110, 120.

[0053] Figure 3A block diagram of a method of imaging an object 140 with an X-ray imaging system 200 according to an embodiment of the application is shown. The method comprises a step S110 of providing the X-ray imaging system 200, a step S120 of positioning the object 140 between the X-ray source 210 and the detection system 100, a step S130 of adjusting a position of at least one of the first detector 110 and the second detector 120 of the detection system 100, and a step S140 of acquiring an image of at least an anatomical region of the object 140. Thus, the region of interest of the object 140 is imaged preferably with increased quality and / or different imaging properties like spectral imaging.

[0054] While the application has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered illustrative or exemplary and not restrictive. The application is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practising the claimed application, from a study of the drawings, the disclosure, and the dependent claims.

[0055] In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. In the claims, the term "consisting of means "including and excluding only". Where an indefinite article such as "a" or "an" is used with reference to an element, this does not exclude several of these elements. Although features have been described with reference to particular combinations and configurations, those combinations and configurations are not necessarily the only ones that can be implemented or that have utility. Those skilled in the art will recognise and appreciate the use of other combinations and configurations not specifically described herein.

Claims

1. A detection system (100) for an X-ray imaging system (200), the detection system comprising: A first detector (110) is configured to detect X-ray radiation (220) from the X-ray imaging system (200) incident on a first detection region (111) of the first detector (110). The second detector (120) is configured to detect X-ray radiation (220) incident on the second detection area (121) of the second detector (120) of the X-ray imaging system (200). The detection system (100) is configured to adjust the position of at least one of the first detector (110) and the second detector (120) relative to the other of the first detector (110) and the second detector (120); and The detection system (100) is configured to locate the first detection area (111) and the second detection area (121) at least partially one after the other, relative to the direction of the X-ray radiation (220) incident on the first detection area (111) of the first detector (110) and the second detection area (121) of the second detector (120); Wherein, the size of the second detection area (121) of the second detector (120) is different from the size of the first detection area (111) of the first detector (110); and The detection system (100) further includes a processing unit (130) configured to reconstruct an X-ray image based on the X-ray radiation (220) detected by the first detector (110) and the second detector (120); The reconstructed X-ray image is characterized by comprising a first region and a second region, wherein the first region is reconstructed based on X-ray radiation (220) detected by both the first detector (110) and the second detector (120), and wherein the second region is reconstructed based on X-ray radiation (220) detected by one of the first detector (110) and the second detector (120), and wherein at least one image characteristic of the X-ray image is better in the first region than in the second region.

2. The detection system (100) according to claim 1, wherein, The first detection area (111) and the second detection area (121) are arranged substantially parallel or concentrically to each other.

3. The detection system (100) according to any one of claims 1 or 2, wherein, The second detector (120) is configured to be translated relative to the first detector (110) in a direction parallel to the surface of the first detection area (111) of the first detector (110) and / or in a direction perpendicular to the surface of the first detection area (111) of the first detector (110).

4. The detection system (100) according to any one of the preceding claims, wherein, The spatial resolution of the second detector (120) is different from that of the first detector (110).

5. The detection system (100) according to any one of the preceding claims, wherein, The transparency of the first detector (110) with respect to the X-ray radiation (220) incident on the first detection area (111) and the second detection area (121) is higher than that of the second detector (120) with respect to the X-ray radiation (220) incident on the first detection area (111) and the second detection area (121).

6. The detection system (100) according to any one of the preceding claims, wherein, The energy sensitivity of the first detector (110) is different from that of the second detector (120).

7. The detection system (100) according to any one of the preceding claims, wherein, At least one of the first detector (120) and the second detector (120) includes an anti-scattering grid.

8. An X-ray imaging system (200) comprising a detection system (100) according to any one of claims 1 to 7, and an X-ray source (210).

9. The X-ray imaging system (200) according to claim 8 further includes a beam collimator, wherein, The beam collimator is configured to focus the X-ray radiation (220) emitted by the X-ray source (210) onto the area covered by the first detection area (111) and the second detection area (121).

10. The X-ray imaging system (200) according to any one of claims 8 or 9, further comprising an irradiation indicator, wherein, The irradiation indicator is configured to visualize an anatomical region of the object (140) to be imaged, the anatomical region being located between the X-ray source (210) and at least one of the first detection region (111) and the second detection region (121).

11. The X-ray imaging system (200) according to claim 10, wherein, The irradiation indicator is configured to visualize separately the anatomical region of the object (140) located between the X-ray source (210) and the first detection area (111) and the anatomical region of the object (140) located between the X-ray source (210) and the second detection area (121).

12. A method for imaging an object (140) using an X-ray imaging system (200) according to any one of claims 8 to 11, the method comprising the steps of: The X-ray imaging system (200) is provided. Position the object (140) between the X-ray source (210) and the detection system (100); Adjusting the position of at least one of the first detector (110) and the second detector (120) of the detection system (100); and Images of at least the anatomical region of the object (140) are acquired.

Images