Method and device for changing a spatial intensity distribution of an X-ray radiation

Abstract

A method for changing a spatial intensity distribution of an X-ray radiation, the method comprising the following steps: - generating (ER) X-ray radiation by an X-ray source (26), - guiding (FS) a beam path (27) of the X-ray radiation through a shaping filter (F), wherein the shaping filter (F) has a plurality of lamellae (L), a holding device (H) for the plurality of lamellae (L) and for each lamella of the plurality of lamellae (L) a lamella bearing (LG), wherein each lamella of the plurality of lamellae (L) has a ferromagnetic region (LB) and is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be movable relative to the holding device (H), wherein each lamella of the plurality of lamellae (L) is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be deflectable relative to the holding device (H) about a rotation axis (LD) of the lamella bearing (LG) of this lamella, wherein for each lamella of the plurality of lamellae (L), the The rotation axis (LD) of the slat support (LG) of this slat is parallel to a longitudinal direction of this slat, - generating (EM) a magnetic field (M) such that for each lamella of the plurality of lamellae (L), the ferromagnetic region (LB) of this lamella interacts with the magnetic field (M) such that a torque is thereby exerted on this lamella about the rotational axis (LD) of the lamella bearing (LG) of this lamella, - Aligning (AL) the plurality of slats (L) relative to the beam path (27) by controlled movement of the plurality of slats (L) relative to the holding device (H) by means of the magnetic field (M), whereby the spatial intensity distribution of the X-ray radiation is changed, - wherein the plurality of slats (L) are aligned by deflecting each slat of the plurality of slats (L) following the torque acting on this slat.

Description

[0001] The invention relates to a method and a device for modifying a spatial intensity distribution of X-ray radiation. The invention further relates to a computed tomography device.

[0002] The use of a blade-based shape filter enables variable, situation-specific X-ray flow. Taking into account the respective diagnostic objective and patient anatomy, the intensity profile should be as flexible and precise as possible. For this purpose, X-ray-absorbing blades are precisely aligned to a common or different focal lines.

[0003] US 10 504 634 B2 discloses a method for adjusting the spatial intensity distribution of an X-ray beam using a shaped filter comprising a plurality of louvres. Further prior art documents include US 2014 / 0 239 204 A1 and US 2019 / 0 001 153 A1.

[0004] In order to fully utilize the power of the X-ray source when required, it is crucial that as little absorbing material as possible, for example in the form of lamellae, actuators, or similar, is present in the beam path when the shape filter is in the appropriate operating state.

[0005] By appropriately aligning the blades, particularly by defocusing them, the X-ray flux should be modulated across the fan angles. Due to the short rotation times of modern computed tomography (CT) scanners, this adjustment should be possible in a very short time. Since the available space in the aperture area, especially in the collimator box, is very limited, the space requirements of this technology should be as small as possible.

[0006] WO 2019 / 161953 A1 discloses a device for modifying the spatial intensity distribution of an X-ray beam using a shaped filter having a plurality of blades, wherein the blades can be moved in a controlled manner, for example, by means of an actuator. In particular, each individual blade can be controlled and thus aligned by an actuator assigned to the respective blade, for example, a piezo actuator or an actuator based on an electroactive polymer (EAP). However, with a number of blades typically several hundred, this requires a very complex spatial arrangement of the components of the shaped filter as well as complex electronic control of the respective actuators.

[0007] The invention aims to enable an improved variation of the spatial intensity distribution of X-rays. Each subject matter of an independent claim solves this problem. Further advantageous aspects of the invention are considered in the dependent claims.

[0008] The invention relates to a method for changing a spatial intensity distribution of X-ray radiation, the method comprising the following steps: - generating X-ray radiation by an X-ray source, - guiding a beam path of the X-ray radiation through a shaped filter, wherein the shaped filter has a plurality of lamellae, a holding device for the plurality of lamellae and a lamella bearing for each lamella of the plurality of lamellae, wherein each lamella of the plurality of lamellae has a ferromagnetic region and is connected to the holding device so as to be movable relative to the holding device by means of the lamella bearing of this lamella, - generating a magnetic field such that for each lamella of the plurality of lamellae, the ferromagnetic region of this lamella interacts with the magnetic field, - Aligning the plurality of slats relative to the beam path by controlled movement of the plurality of slats relative to the holding device by means of the magnetic field, whereby the spatial intensity distribution of the X-ray radiation is changed.

[0009] One embodiment provides that the magnetic field is generated by generating a plurality of individual magnetic fields (M1, M2) and the magnetic field results from a superposition of the individual magnetic fields of the plurality of individual magnetic fields (M1, M2).

[0010] The invention provides that each lamella of the plurality of lamellas is connected to the holding device by means of the lamella mounting of this lamella relative to the holding device so as to be deflectable about a rotational axis of the lamella mounting of this lamella, wherein for each lamella of the plurality of lamellas, the ferromagnetic region of this lamella interacts with the magnetic field in such a way that a torque is thereby exerted on this lamella about the rotational axis of the lamella mounting of this lamella, wherein the plurality of lamellas is aligned by each lamella of the plurality of lamellas being deflected following the torque acting on this lamella.

[0011] The invention further relates to a device for changing a spatial intensity distribution of an X-ray radiation, comprising - a shaped filter which can be introduced into a beam path of the X-ray radiation generated by an X-ray source, wherein the shaped filter has a plurality of blades, a holding device for the plurality of blades, and a blade bearing for each blade of the plurality of blades, wherein each blade of the plurality of blades has a ferromagnetic region and is connected to the holding device by means of the blade bearing of this blade so that it can move relative to the holding device (H), and wherein the plurality of blades can be aligned relative to the beam path by a controlled movement of the plurality of blades relative to the holding device by means of a magnetic field, - a magnetic field generation system which is designed to generate the magnetic field, and - a control unit which is designed to control the controlled movement of the plurality of slats by means of the magnetic field and thereby to change the spatial intensity distribution of the X-ray radiation.

[0012] By adjusting the magnetic field accordingly, the blades can be aligned quickly and precisely. This allows for contactless adjustment of a blade-shaped filter, particularly contactless alignment of the blades. The blades can be dynamically deflected within a short time using the magnetic field. The alignment of the blades can be synchronized by having all blades interact with the same magnetic field. This allows for different intensity profiles to be realized.

[0013] A contact-based alignment of each individual blade is therefore not necessary. With a contact-based solution, several hundred actuators would have to be controlled to move the blades. With the solution according to the invention, the complexity is reduced to the control of a magnetic field. This also makes it possible to reduce material costs. The difficulty of spatially arranging many individual actuators is obsolete. To deflect the blades, only the components of the magnetic field generation system are required, which can be located outside the beam path. This allows for better use of the available installation space, especially in the area of ​​a collimator for collimating the X-ray beam path.

[0014] In addition to the lamellae of the plurality of lamellae, the shaped filter can have further lamellae that, for example, do not include a ferromagnetic region and / or are not arranged to be movable by means of a lamella bearing. Furthermore, it can be provided that each lamella of the plurality of lamellae is arranged in the holding device such that for each lamella of the plurality of lamellae, there is at least one straight line running through this lamella that is parallel to the further lamellae.

[0015] One embodiment provides that the magnetic field generation system is designed to generate a plurality of individual magnetic fields and the magnetic field results from a superposition of the individual magnetic fields of the plurality of individual magnetic fields.

[0016] By generating and superimposing multiple individual magnetic fields, the lamellae can be aligned more variably. This results in a greater variety of possible intensity profiles.

[0017] One embodiment provides that the magnetic field generation system has at least one electromagnet for generating the magnetic field.

[0018] One embodiment provides that the magnetic field generation system is arranged outside the beam path of the X-ray radiation.

[0019] The at least one electromagnet can be based on a coil, in particular a cylindrical coil. The magnetic field can be generated by the at least one electromagnet, in particular such that the ferromagnetic regions of the lamellae are located within the magnetic field. This can also be achieved such that the actual source of the magnetic fields, in particular the at least one electromagnet, is located outside the beam path, but their effect in the form of aligning the lamellae occurs within the beam path.

[0020] The invention provides that each lamella of the plurality of lamellas is connected to the holding device by means of the lamella mounting of this lamella relative to the holding device so as to be deflectable about a rotational axis of the lamella mounting of this lamella, wherein for each lamella of the plurality of lamellas, the ferromagnetic region of this lamella interacts with the magnetic field in such a way that a torque is thereby exerted on this lamella about the rotational axis of the lamella mounting of this lamella, wherein each lamella of the plurality of lamellas is deflectable following the torque acting on this lamella.

[0021] One embodiment provides that the magnetic field generation system has a first electromagnet in the form of a first cylinder coil and / or that the magnetic field generation system has a second electromagnet in the form of a second cylinder coil.

[0022] In particular, it can be provided that an axis of the second solenoid is parallel to an axis of the first solenoid. In particular, it can be provided that for each lamella of the plurality of lamellas, the axis of rotation of the lamella mounting of this lamella is parallel to an axis of the first solenoid and / or that for each lamella of the plurality of lamellas, the axis of rotation of the lamella mounting of this lamella is parallel to an axis of the second solenoid.

[0023] One embodiment provides that the first electromagnet and the second electromagnet are arranged opposite each other with respect to the beam path of the X-ray radiation.

[0024] One embodiment provides that for each lamella of the plurality of lamellas, the ferromagnetic region is arranged at that edge of this lamella which is opposite the axis of rotation of the lamella bearing of this lamella.

[0025] In particular, an edge of the slat which is as far away as possible from a pivot point of a suspension of the slat can be ferromagnetic.

[0026] One embodiment provides that each lamella of the plurality of lamellas is made entirely or partially of a ferromagnetic material.

[0027] One embodiment provides that each lamella of the plurality of lamellae each has a core region by which an X-ray absorption effect of this lamellae is essentially determined, wherein each lamella of the plurality of lamellae each has a ferromagnetic coating which is applied to at least a partial region of the core region of this lamellae and which forms at least a partial region of the ferromagnetic region, in particular the ferromagnetic region.

[0028] In particular, the core region of the lamella can be predominantly made of a material that absorbs X-rays relatively strongly, in particular significantly more strongly than the ferromagnetic material from which the ferromagnetic coating is made. In particular, the core region of each lamella can be completely or partially coated with the ferromagnetic material.

[0029] The invention further relates to a computer tomography apparatus comprising a device according to one of the disclosed aspects.

[0030] One embodiment provides a computed tomography device, further comprising a support frame and a rotating frame, wherein the rotating frame is mounted rotatably about a rotation axis relative to the support frame, wherein the X-ray source and the shaping filter are arranged on the rotating frame, wherein the shaping filter is arranged between the X-ray source and the rotation axis.

[0031] Within the scope of the invention, features described in relation to different embodiments of the invention and / or different claim categories (method, use, device, system, arrangement, etc.) can be combined to form further embodiments of the invention. For example, a claim relating to a device can also be further developed with features described or claimed in connection with a method, and vice versa. Functional features of a method can be implemented by appropriately designed physical components. In addition to the embodiments of the invention expressly described in this application, a wide variety of further embodiments of the invention are conceivable, which the person skilled in the art can arrive at without departing from the scope of the invention as defined by the claims.

[0032] In the context of the present application, the expression "based on" can be understood in particular in the sense of the expression "using." In particular, a formulation according to which a first feature is generated (alternatively: determined, determined, etc.) based on a second feature does not exclude the possibility that the first feature can be generated (alternatively: determined, determined, etc.) based on a third feature.

[0033] The invention is explained below using exemplary embodiments with reference to the accompanying figures. The representations in the figures are schematic, highly simplified, and not necessarily to scale.

[0034] They show: the Fig. 1 a first side view of a form filter, the Fig. 2 a second side view of the form filter, the Fig. 3 the majority of the lamellae of the shaped filter without a magnetic field, the Fig. 4 the majority of lamellae of the shaped filter with a single magnetic field, the Fig. 5 the majority of lamellae of the shaped filter with two superimposed individual magnetic fields, the Fig. 6 a computer tomography device, and the Fig. 7 a flow chart for a method for changing a spatial intensity distribution of an X-ray radiation.

[0035] The Fig. 1 shows a first side view of a form filter F. The Fig. 2 shows a second side view of the shaping filter F. The beam path 27 of the X-ray radiation is guided through the shaping filter F. Alternatively or in addition to the Fig. 1 shown slats with a curved height profile, slats with a substantially rectangular or trapezoidal height profile can also be used for the shaped filter.

[0036] The shaped filter F has a plurality of lamellae L, a holding device H for the plurality of lamellae L and a lamella bearing LG for each lamella of the plurality of lamellae L, wherein each lamella of the plurality of lamellae L has a ferromagnetic region LB and is connected to the holding device H by means of the lamella bearing LG of this lamella so as to be movable relative to the holding device H. Each lamella of the plurality of lamellae L is connected to the holding device H by means of the lamella bearing LG of this lamella so as to be deflectable relative to the holding device H about a rotation axis LD of the lamella bearing LG of this lamella.

[0037] The first electromagnet S1 is a first solenoid coil. For each lamella of the plurality of lamellas L, the rotation axis LD of the lamella bearing LG of this lamella is parallel to an axis AS1 of the first solenoid coil.

[0038] The Fig. Figure 3 shows the plurality of lamellae L of the shaped filter F without a magnetic field. For each lamella of the plurality of lamellae L, the ferromagnetic region LB is arranged at the edge of this lamella opposite the rotation axis LD of the lamella support LG of this lamella. Each lamella of the plurality of lamellae L has a core region LA, which essentially determines the X-ray absorption effect of this lamella. Each lamella of the plurality of lamellae L has a ferromagnetic coating applied to a portion of the core region L of this lamella, forming the ferromagnetic region LB.

[0039] The Fig. Figure 4 shows the plurality of lamellae L of the shaped filter F with a single magnetic field M2 generated by the second electromagnet S2. The second electromagnet S2 is a second solenoid coil. For each lamella of the plurality of lamellae L, the rotation axis LD of the lamella support LG of this lamella is parallel to an axis AS2 of the second solenoid coil and parallel to the z-axis of the drawn coordinate system.

[0040] For each lamella of the plurality of lamellae L, the ferromagnetic region LB of this lamella interacts with the magnetic field M in such a way that a torque is exerted on this lamella around the rotation axis LD of the lamella bearing LG of this lamella. Fig. In the operating state of the shaped filter F shown in Figure 4, each lamella of the plurality of lamellae L is deflected following the torque acting on this lamella.

[0041] The Fig. 5 shows the majority of lamellae L of the shaped filter F with two superimposed individual magnetic fields M1 and M2.

[0042] The individual magnetic field M1 is generated by the first electromagnet S1. The individual magnetic field M2 is generated by the second electromagnet S2. The first electromagnet S1 and the second electromagnet S2 are arranged opposite each other with respect to the X-ray beam path 27. The magnetic field M results from the superposition of the individual magnetic fields M1 and M2. Each of the individual magnetic fields M1 and M2 also acts beyond the largest radius indicated for this individual magnetic field.

[0043] The Fig. 6 shows a computed tomography device 2. The computed tomography device 2 has the gantry 20, the tunnel-shaped opening 9, the patient support device 10 and the device 1 for changing a spatial intensity distribution of an X-ray radiation.

[0044] The device 1 comprises the shaping filter F, the magnetic field generation system MS, and the control unit 35. The gantry 20 comprises the support frame 21 and the rotating frame 24, wherein the rotating frame 24 is mounted rotatably relative to the support frame 21 about the rotation axis AR. The X-ray source 26, the shaping filter F, and the radiation detector 28 are arranged on the rotating frame 24, wherein the shaping filter F is arranged between the X-ray source 26 and the rotation axis AR. The rotation axis AR is parallel to the z-direction of the drawn coordinate system. The z-axis is perpendicular to both the x-axis and the y-axis. The x-axis is perpendicular to the y-axis and parallel to a radial direction directed perpendicularly away from the rotation axis AR toward the X-ray source 26.

[0045] The patient 13 can be inserted into the tunnel-shaped opening 9. The acquisition region 4 is located in the tunnel-shaped opening 9. In the acquisition region 4, a region of the patient 13 to be imaged can be positioned such that the radiation 27 from the X-ray source 26 can reach the region to be imaged and, after interacting with the region to be imaged, can reach the radiation detector 28. The patient support device 10 has the support base 11 and the support plate 12 for supporting the patient 13. The support plate 12 is arranged on the support base 11 so as to be movable relative to the support base 11 such that the support plate 12 can be inserted into the acquisition region 4 in a longitudinal direction of the support plate 12.

[0046] The X-ray source 26 is arranged on the rotating frame 24 and is configured to emit radiation 27, e.g., X-rays, containing radiation quanta. The detector 28 is arranged on the rotating frame 24 and configured to detect the radiation quanta by direct conversion. The radiation quanta can travel from the X-ray source 26 to the area of ​​the patient 13 to be imaged and, after interacting with the area to be imaged, impinge on the detector 28. In this way, acquisition data of the area to be imaged can be acquired in the form of projection data using the acquisition unit.

[0047] The control device 30 is configured to receive the acquisition data acquired by the acquisition unit. The control device 30 is configured to control the computed tomography device 2. The control device 30 includes the image reconstruction device 34, the control unit 35, the computer-readable medium 32, and the processor system 36. The control device 30, in particular the control unit 35, is formed by a computer.

[0048] The control unit 35 is designed to control the controlled movement of the plurality of slats L using the magnetic field M, thereby changing the spatial intensity distribution of the X-ray radiation. The control unit 35 is connected via a data transmission link to the power supply unit MI of the magnetic field generation system MS, which supplies power to the two electromagnets S1 and S2.

[0049] The computed tomography device 2 has an input device 38 and an output device 39, each of which is connected to the control device 30. The input device 38 is designed to input control information, e.g., image reconstruction parameters, examination parameters, or the like. The output device 39 is designed, in particular, to output control information, images, and / or acoustic signals.

[0050] The Fig. 7 shows a flowchart for a method for changing a spatial intensity distribution of an X-ray radiation, the method comprising the following steps: - Generation of X-ray radiation by an X-ray source 26, - guiding FS of a beam path 27 of the X-ray radiation through a shaping filter F, wherein the shaping filter F has a plurality of lamellae L, a holding device H for the plurality of lamellae L and a lamella bearing LG for each lamella of the plurality of lamellae L, wherein each lamella of the plurality of lamellae L has a ferromagnetic region LB and is connected to the holding device H by means of the lamella bearing LG of this lamella so as to be movable relative to the holding device H, - generating EM a magnetic field M such that for each lamella of the plurality of lamellae L, the ferromagnetic region LB of this lamella interacts with the magnetic field M, and - Aligning AL the plurality of slats L relative to the beam path 27 by controlled movement of the plurality of slats L relative to the holding device H by means of the magnetic field M, whereby the spatial intensity distribution of the X-radiation is changed.

Claims

[1] A method for changing a spatial intensity distribution of an X-ray radiation, the method comprising the following steps: - generating (ER) X-ray radiation by an X-ray source (26), - guiding (FS) a beam path (27) of the X-ray radiation through a shaping filter (F), wherein the shaping filter (F) has a plurality of lamellae (L), a holding device (H) for the plurality of lamellae (L) and for each lamella of the plurality of lamellae (L) a lamella bearing (LG), wherein each lamella of the plurality of lamellae (L) has a ferromagnetic region (LB) and is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be movable relative to the holding device (H), wherein each lamella of the plurality of lamellae (L) is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be deflectable relative to the holding device (H) about a rotation axis (LD) of the lamella bearing (LG) of this lamella, wherein for each lamella of the plurality of lamellae (L), the The rotation axis (LD) of the slat support (LG) of this slat is parallel to a longitudinal direction of this slat, - generating (EM) a magnetic field (M) such that for each lamella of the plurality of lamellae (L), the ferromagnetic region (LB) of this lamella interacts with the magnetic field (M) such that a torque is thereby exerted on this lamella about the rotational axis (LD) of the lamella bearing (LG) of this lamella, - Aligning (AL) the plurality of slats (L) relative to the beam path (27) by controlled movement of the plurality of slats (L) relative to the holding device (H) by means of the magnetic field (M), whereby the spatial intensity distribution of the X-ray radiation is changed, - wherein the plurality of slats (L) are aligned by deflecting each slat of the plurality of slats (L) following the torque acting on this slat. [2] Method according to claim 1, - wherein the magnetic field (M) is generated by generating a plurality of individual magnetic fields (M1, M2) and the magnetic field (M) results from a superposition of the individual magnetic fields of the plurality of individual magnetic fields (M1, M2). [3] Device (1) for changing a spatial intensity distribution of an X-ray radiation, comprising - a shaped filter (F) which can be introduced into a beam path (27) of the X-ray radiation generated by an X-ray source (11), wherein the shaped filter (F) has a plurality of lamellae (L), a holding device (H) for the plurality of lamellae (L), and a lamella bearing (LG) for each lamella of the plurality of lamellae (L), wherein each lamella of the plurality of lamellae (L) has a ferromagnetic region (LB) and is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be movable relative to the holding device (H), wherein each lamella of the plurality of lamellae (L) is connected to the holding device (H) by means of the lamella bearing (LG) of this lamella so as to be deflectable relative to the holding device (H) about a rotation axis (LD) of the lamella bearing (LG) of this lamella,wherein for each lamella of the plurality of lamellas (L), the axis of rotation (LD) of the lamella mounting (LG) of this lamella is parallel to a longitudinal direction of this lamella, wherein the plurality of lamellas (L) can be aligned relative to the beam path (27) by a controlled movement of the plurality of lamellas (L) relative to the holding device (H) by means of a magnetic field (M), wherein for each lamella of the plurality of lamellas (L), the ferromagnetic region (LB) of this lamella interacts with the magnetic field (M) in such a way that a torque is thereby exerted on this lamella about the axis of rotation (LD) of the lamella mounting (LG) of this lamella, and wherein each lamella of the plurality of lamellas (L) can be deflected following the torque acting on this lamella, - a magnetic field generation system (MS) which is designed to generate the magnetic field (M), and - a control unit (35) which is designed to control the controlled movement of the plurality of slats (L) by means of the magnetic field (M) and thereby to change the spatial intensity distribution of the X-ray radiation. [4] Device (1) according to claim 3, - wherein the magnetic field generation system (MS) is designed to generate a plurality of individual magnetic fields (M1, M2) and the magnetic field (M) results from a superposition of the individual magnetic fields of the plurality of individual magnetic fields (M1, M2). [5] Device (1) according to claim 3 or 4, - wherein the magnetic field generation system (MS) comprises at least one electromagnet (S1, S2) for generating the magnetic field. [6] Device (1) according to one of claims 3 to 5, - wherein the magnetic field generation system (MS) is arranged outside the beam path (27) of the X-ray radiation. [7] Device (1) according to one of claims 3 to 6, - wherein the magnetic field generation system (MS) comprises a first electromagnet (S1) in the form of a first cylinder coil and / or - wherein the magnetic field generation system (MS) comprises a second electromagnet (S2) in the form of a second cylindrical coil. [8] Device (1) according to claim 7, - wherein the first electromagnet (S1) and the second electromagnet (S2) are arranged opposite one another with respect to the beam path (27) of the X-ray radiation. [9] Device (1) according to one of claims 3 to 8, - wherein for each lamella of the plurality of lamellae (L), the ferromagnetic region (LB) is arranged at that edge of this lamella which is opposite the axis of rotation (LD) of the lamella bearing (LG) of this lamella. [10] Device (1) according to one of claims 3 to 9, - wherein each lamella of the plurality of lamellae (L) is made entirely or partially of a ferromagnetic material. [11] Device (1) according to one of claims 3 to 10, - wherein each lamella of the plurality of lamellae (L) has a core region (LA) by which an X-ray absorption effect of this lamella is essentially determined, - wherein each lamella of the plurality of lamellae (L) has a ferromagnetic coating which is applied to at least a partial region of the core region (L) of this lamella and which forms at least a partial region of the ferromagnetic region (LB). [12] Computed tomography device (2) comprising a device according to one of claims 3 to 11. [13] Computed tomography device (2) according to claim 12, further comprising a support frame (21) and a rotating frame (24), wherein the rotating frame (24) is mounted rotatably relative to the support frame (21) about a rotation axis (AR), - wherein the X-ray source (26) and the shaping filter (F) are arranged on the rotating frame (24), - wherein the shape filter (F) is arranged between the X-ray source (26) and the rotation axis (AR).

Images