Filter system for the local attenuation of X-radiation, X-ray apparatus and method for locally changing the intensity of X-radiation

A filter system is for the local attenuation of X-radiation. In an embodiment, the filter system includes a filter device, arranged in a beam path of an X-ray apparatus and including a channel arrangement, the channel arrangement including a multiplicity of channel sections extending in parallel on a plane; a supply device to provide a 2-phase fluid flow containing drops of an absorber liquid, to absorb X-radiation and a carrier liquid transparent to X-radiation; and a sorting section, including an input connected to the supply device, a first output connected to the channel arrangement, a second output, and a deflection device to direct individual drops of the absorber liquid to the first output or the second output.

PRIORITY STATEMENT

The present application hereby claims priority under 35 U.S.C. § 119 to European patent application number EP 19163502.8 filed Mar. 18, 2019, the entire contents of which are hereby incorporated herein by reference.

FIELD

Embodiments of the invention generally relate to a filter system for the local attenuation of X-radiation, an X-ray apparatus and a method for locally changing the intensity of X-radiation.

BACKGROUND

During X-ray examinations of patients, X-radiation is directed at the region to be examined in the body of the patient. In this context, the situation can occur that the region to be examined has locally differing absorption characteristics for X-rays. For example, soft tissue, organs and bones each have different absorption characteristics. As a consequence, those regions of interest for the medical examination might not be very clearly visible within an X-ray scan.

In consideration of the above, and in order to limit as far as possible a radiation dose for the patient during the examination, use is generally made of X-ray filters for local attenuation of the X-radiation. For example, DE 10 2012 206 953 B3 describes an X-ray filter which is arranged in the beam path of an X-ray apparatus, comprising a liquid that absorbs X-radiation and is arranged between a membrane and a cover plate, wherein a layer thickness of the liquid can be changed locally via control elements in order to adjust the attenuation of the radiation locally.

U.S. Pat. No. 3,755,672 A describes an X-ray filter with an absorber liquid which is arranged between two plates, wherein one of the plates is flexible and a distance between the plates can be varied via servomotors. U.S. Pat. No. 9,966,159 B2 describes an X-ray filter in which an absorber liquid is displaced via electrical forces using an electrode arrangement in order to open a beam path locally. U.S. Pat. No. 6,453,012 B2 describes an X-ray apparatus with a filter system which comprises a filter device having a plurality of filter elements in the form of tubes that extend in the direction of radiation. The tubes are filled from one end with an absorber liquid in order to locally adjust an attenuation of the radiation by way of so-called “electrowetting”.

U.S. Pat. No. 4,856,042 A further describes an X-ray filter with a chamber that is formed between an upper and a lower plate, in which separating walls are so arranged as to extend radially from an opening of the lower plate. Alcohol can be supplied to the chamber through the opening. Mercury can be supplied to the chamber through a nozzle at a radial edge region, such that part-spaces which are separated from each other by the separating walls can be filled in some cases with alcohol and in some cases with mercury in a radial direction.

The publication JP H02 257942 A describes a radiation filter inFIG. 3, comprising a plurality of parallel tubular bodies containing mercury, wherein a region containing a liquid that allows radiation to pass is arranged between two regions that contain mercury. The mercury or the region containing a liquid that allows radiation to pass and is arranged between the mercury regions can be moved by changing a cross section at the end of the respective tube body via a piezoelectric element within the tube body.

SUMMARY

In consideration of the above, an improved design for an X-ray filter is desired, particularly an X-ray filter having a simple structure.

Advantageous embodiments are specified in the claims.

According to a first embodiment of the invention, a filter system is provided for the local attenuation of X-radiation. The filter system comprises a filter device, which is arranged in the beam path of an X-ray apparatus and has a channel arrangement with a multiplicity of channel sections extending parallel to each other on a plane, and a supply device for providing a 2-phase fluid flow, said flow containing drops of an absorber liquid which absorbs X-radiation and a carrier liquid that is transparent to X-radiation.

According to a second embodiment of the invention, provision is made for an X-ray apparatus. The X-ray apparatus comprises an X-ray source for generating and emitting X-radiation in a beam path, an X-ray detector which is arranged in the beam path, and a filter system according to the first embodiment, wherein the filter device is arranged in the beam path between X-ray source and X-ray detector. For example, the filter device can be arranged in the beam path in such a way that the channel sections extend transversely relative to the beam path.

According to a third embodiment of the invention, provision is made for a method for locally changing the intensity of X-radiation. The method can be performed in particular using a system according to the first embodiment of the invention and an X-ray apparatus according to the second embodiment of the invention. The method comprises generating predetermined sequences of drops from a 2-phase fluid flow containing drops of an absorber liquid which absorbs X-radiation and a carrier liquid that is transparent to X-radiation, and supplying said drop sequences into channel sections of a channel arrangement of a filter device which is arranged in a beam path between an X-ray source and an X-ray detector, wherein the channel arrangement has a multiplicity of channel sections extending parallel to each other on a plane. The advantages cited in respect of the system and the X-ray apparatus apply to the method likewise.

According to a further example, provision is made for a filter system for the attenuation of X-radiation, comprising a filter device, which is arranged in the beam path of an X-ray apparatus and has two plates that are arranged parallel to each other and define an intermediate space, and a supply device for providing a 2-phase fluid flow containing drops of an absorber liquid that absorbs X-radiation and a carrier liquid that is transparent to X-radiation, said supply device being connected to the intermediate space. The filter system optionally also comprises a sorting section with an input that is connected to the supply device, a first output that is connected to the intermediate space, a second output, and a deflection device for directing individual drops of the absorber liquid to the first output or the second output. The optional sorting section and the supply device can be developed as described above.

According to another embodiment of the invention, provision is made for a filter system for local attenuation of X-radiation, comprising:

a filter device, arranged in a beam path of an X-ray apparatus and including a channel arrangement, the channel arrangement including a multiplicity of channel sections extending in parallel on a plane;

a supply device to provide a 2-phase fluid flow containing drops of an absorber liquid, to absorb X-radiation and a carrier liquid transparent to X-radiation; and

a sorting section, including an input connected to the supply device, a first output connected to the channel arrangement, a second output, and a deflection device to direct individual drops of the absorber liquid to the first output or the second output.

According to another embodiment of the invention, provision is made for an X-ray apparatus, comprising:

an X-ray source to generate and emit X-radiation in a beam path;

an X-ray detector, arranged in the beam path; and

the filter system of an embodiment, wherein the filter device of the filter system is arranged in the beam path, between the X-ray source and the X-ray detector.

According to another embodiment of the invention, provision is made for a method for locally changing the intensity of X-radiation, the method comprising:

generating sequences of drops from a 2-phase fluid flow containing drops of an absorber liquid, to absorb X-radiation and a carrier liquid, transparent to X-radiation; and

supplying the drop sequences generated into channel sections of a channel arrangement of a filter device, arranged in a beam path between an X-ray source and an X-ray detector, wherein the channel arrangement includes a multiplicity of channel sections extending in parallel on a plane.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

According to a first embodiment of the invention, a filter system is provided for the local attenuation of X-radiation. The filter system comprises a filter device, which is arranged in the beam path of an X-ray apparatus and has a channel arrangement with a multiplicity of channel sections extending parallel to each other on a plane, and a supply device for providing a 2-phase fluid flow, said flow containing drops of an absorber liquid which absorbs X-radiation and a carrier liquid that is transparent to X-radiation.

A concept underlying at least one embodiment of the invention resides in generating a specific sequence of liquid drops of an absorber material which absorbs X-radiation and liquid drops of a carrier material which allows X-radiation to be transmitted and cannot be mixed with the absorber material, positioning this sequence of drops in a planar channel system, and arranging the channel system in the beam path of an X-ray apparatus. The X-rays are thereby wholly or partially absorbed or attenuated at those points of the channel system at which drops of absorber material are arranged.

For the purpose of positioning the drops in the beam path, provision is made for a filter device with a channel arrangement. The channel arrangement has a planar extent, which is defined by a multiplicity of adjacently arranged channel sections running in parallel. Each channel section can be supplied with a drop sequence which is predetermined in relation to the longitudinal extent of the respective channel section. For this purpose, the channel arrangement is connected to a supply device.

The supply device delivers a two-phase fluid flow, in which one phase is formed by drops of absorber liquid and the other phase by drops of carrier liquid. One advantage of the invention is that the filter device with the channel arrangement, which is intended to be arranged in the beam path, has a very simple design format and includes essentially hydraulic line structures.

According to a further embodiment variant of the filter system, provision is made for the supply device to have a first reservoir containing the absorber liquid, a second reservoir containing the carrier liquid, and a drop generator for generating the 2-phase fluid flow, wherein the drop generator is connected via a first input to the first reservoir, via a second input to the second reservoir, and via an output to the channel arrangement. According to this embodiment variant, the individual drops from which the 2-phase fluid flow is composed are generated by a drop generator, this being configured to cut off a first fluid flow of absorber liquid and a second fluid flow of carrier liquid alternately, in order thus to generate a desired and optionally periodic drop sequence. The drop sequence can conceivably be generated with drops of different length, in order to provide the desired sequence of drops with reference to an absorption pattern. It is also possible to generate periodic drop sequences with drops of essentially the same size and regular intervals, which are then sorted according to the desired absorption pattern by a sorting section which is connected to the output of the drop generator as described below.

According to an embodiment variant, the drop generator can have a first line section comprising the first input and a second line section comprising the second input, said first and the second line sections merging with each other in a T-shaped junction. Therefore the drop generator is embodied as a T-piece, to which absorber liquid is supplied at a first input and carrier liquid is supplied at a second input. A particularly simple format can be achieved thereby. Optionally, the drop generator can also have a first valve connected to the first input first and a second valve connected to the second input, wherein the valves can each be switched between an open state and a closed state in order to interrupt or allow the fluid throughput in each case. For example, the valves can be embodied as magnetic valves. Adjustment of the drop size is simplified by the valves.

According to a further embodiment variant of the filter system, provision is made for the supply device to have a reservoir with an emulsion of drops of the absorber liquid and the carrier liquid, and for the reservoir to be connected to the input of the sorting section. For example, a stabilizer such as e.g. PEG (polyethylene glycol) or silicone oil from which oxygen has been removed can be added to the carrier liquid for this purpose. The provision of an emulsion in a reservoir further simplifies the format of the filter system.

According to an embodiment of the invention, provision is made for the filter system to have a sorting section with an input that is connected to the supply device, a first output that is connected to the channel arrangement, a second output, and a deflection device for directing individual drops of the absorber liquid to the first output or the second output. The 2-phase fluid flow provided by the supply device is supplied to the sorting section, which is designed to separate individual drops, in particular drops of absorber liquid, out of the fluid flow. For this purpose, the sorting section has a deflection device for applying a force to the drops, said force being transverse to the direction of flow, such that the drops are supplied either to a first output which is connected in a fluidically conductive manner to the channel arrangement, or to a second output which is not connected to the channel arrangement but to e.g. a reservoir. In this way, it is possible to generate specific drop sequences efficiently. For example, the deflection device can have a first electrode and a second electrode arranged opposite thereto, in order to generate an electrical field for deflecting the drops in a separation section which extends between the input and the outputs of the sorting section. Alternatively, the deflection device can also be designed to generate a pressure pulse in order to deflect the individual drops.

Via the sorting section, it is possible to generate almost any desired drop sequences and hence absorption patterns for local attenuation of the X-radiation in an efficient manner. The regions in which the X-radiation is to be attenuated can therefore be selected in a flexible manner.

According to an embodiment variant of the filter system, provision is made for the channel sections of the channel arrangement to be connected to each other via connecting sections in such a way that they form a continuous channel. The optional sorting section can be connected via its first output to an input of the channel in particular. Accordingly, each channel section is connected at its end to a further, adjacent channel section via a connecting section which is e.g. U-shaped. A meandering continuous channel with parallel channel sections is thus formed. This has the advantage that the whole channel arrangement or each individual channel section of the channel arrangement can be filled with a drop pattern via a single sorting section. This further simplifies the format of the filter system.

Alternatively, the channel sections of the channel arrangement can each be formed by individual channels which are each connected to the supply device. In this case, the filter system can have a number of sorting sections which corresponds to the number of channel sections, wherein each channel of the channel arrangement is connected in each case to a first output of a respective sorting section. Therefore the channel arrangement is formed by a multiplicity of individual separate channels or lines, and each channel is connected to the supply device directly or is optionally connected to the supply device via a sorting section which is assigned to the channel in each case. This layout has the advantage that all channel sections of the channel arrangement can be filled with drop sequences simultaneously.

According to a further embodiment variant of the filter system, provision is made for a first group of channel sections of the channel arrangement to be arranged on a first plane and for one or more further groups of channel sections to be provided, each of these being arranged on planes which are parallel to the first plane. The channel arrangement can therefore have a plurality of groups of channel sections extending in parallel, the channel sections of a respective group extending on a plane in each case, and the planes being parallel to each other. For example, between two and ten groups of channel sections may be provided. This has the advantage that the degree of attenuation of the radiation can be adjusted by arranging droplets of absorption liquid such that they overlap on the different planes.

According to a further embodiment variant, the channel arrangement has at least two plates which abut each other at their surfaces, wherein grooves defining the channel sections are formed on the surfaces in each case. In particular, a first plate has first grooves on a first surface, a second plate has second grooves on a second surface, and said second grooves run in a manner which corresponds to the first grooves, wherein the first surface of the first plate abuts the second surface of the second plate. A simple design format is thus realized for the channel arrangement. For example, by way of this format it is also possible advantageously to realize a channel arrangement having channel sections on a plurality of planes. The plates can be made of a plastic material such as e.g. PMMA (polymethyl methacrylate), glass or other material which is largely transparent to X-radiation.

According to an embodiment variant, mercury or Galinstan is used as an absorber liquid. The carrier liquid can be in particular an oil, e.g. silicone oil.

For the purpose of transporting the drops, or the 2-phase fluid flow generally, into and out of the channel arrangement, provision can be made for e.g. hydraulic pressure generating devices such as pumps and optionally valves. For example, the reservoir containing the emulsion or the reservoir containing carrier liquid and the reservoir containing absorber liquid can be connected in each case via a pump to the input of the sorting section or of the drop generator. Alternatively, it is also conceivable to equip the channel sections with an electrode arrangement for this purpose, wherein a group of first electrodes is so arranged as to be distributed along the channel sections in an electrically insulating manner, and at least one second electrode in each case is provided in a channel section in each case. The second electrode can be grounded. The first electrodes can be connected to an electrical voltage source consecutively in a temporal sequence. If an electrolyte is added to the carrier liquid or if the absorber liquid is electrically conductive, it is then possible to apply the principle known as “electrowetting” for the purpose of transporting drops in the channel sections. Alternatively, it is also conceivable to generate a wandering electrical field along the channel sections via an electrode arrangement, and to move the drops of absorber liquid via electrostatic forces. Generally, a transport device which is coupled to the channel sections can be provided for the purpose of transporting the 2-phase fluid flow.

According to a second example of the disclosure, a filter system for the attenuation of X-radiation is provided, comprising a filter device, which is arranged in the beam path of an X-ray apparatus and has a channel arrangement with a multiplicity of channels extending parallel to each other on a plane, a reservoir containing an absorber liquid which absorbs X-radiation, wherein the channels are connected to the reservoir at opposite ends in each case, and a transport system for the transportation of absorber liquid in the channels.

A concept underlying this example resides in achieving a simple format of a filter device via individual channels which extend in parallel, and in filling these channels from opposite sides with liquid columns of an absorber fluid such as e.g. Galinstan or mercury. It is consequently possible using a very simple design format to effect a local attenuation of the X-radiation via the liquid columns of absorber liquid.

According to this example, the channel arrangement is formed by a multiplicity of individual separate channels or lines. Each of the channels is connected to the reservoir in a fluidically conductive manner via a first end and a second end which is positioned opposite thereto. This layout has the advantage that all channel sections of the channel arrangement can be filled with absorber fluid from opposites sides simultaneously.

According to an embodiment variant of this example, provision is made for the absorber liquid to have an electrically conductive component, wherein the transport system has an electrode arrangement with a multiplicity of electrodes arranged along the channels and a switch device which is designed to connect the electrodes individually in each case to an electrical voltage source. Provision is therefore made for transporting the absorber liquid via electrical forces, e.g. via electrostatic forces or by way of so-called “electrowetting”.

The phenomenon of the electrowetting is based on varying a contact angle between a liquid, here the absorber liquid, and a surface, here the surface of the channel, by applying an electrical potential. For example, a surface voltage gradient can be electrically induced over the length of a liquid metal slug which is situated between electrolytic liquids, whereby Marangoni forces are generated along the liquid-liquid boundary surface and a movement of the slug is provoked. However, the liquid itself can also be electrically conductive. For the purpose of transporting the absorber liquid in the channels, the electrode arrangement can have e.g. a multiplicity of first electrodes, which are arranged along the individual channels and are electrically insulated from the absorber liquid, e.g. by virtue of the channels being made of electrically insulating material and the electrodes being fastened to an outer surface of the channels. The first electrodes apply a first electrical potential to the channel walls. A second electrode is arranged in the interior of the channels and applies a second electrical potential to the absorber liquid. The switch device connects the individual first electrodes consecutively to the voltage source, whereby transportation of the absorber fluid along the channels is achieved.

For the purpose of transportation by way of electrostatic forces, a multiplicity of opposing first and second electrodes can be distributed along the longitudinal extent of each channel, such that these form a capacitor when a voltage is applied. By connecting the electrodes consecutively to a voltage source, a moving electrical field can be generated along a respective channel123in order to transport the absorber liquid.

According to a further embodiment variant of this example, provision is made for the transport system to take the form of a hydraulic system comprising at least one pump, this being arranged between the reservoir and the channel arrangement.

According to a further embodiment variant of this example, a first group of channels is arranged on a first plane and one or more further groups of channels are each arranged on planes parallel to the first plane. The channel arrangement can therefore have a plurality of groups of channels extending in parallel, the channels of a respective group extending on a plane in each case, and the planes being parallel to each other. For example, between two and ten groups of channels may be provided. This has the advantage that the degree of attenuation of the radiation can be adjusted by arranging the liquid columns of absorption liquid such that they overlap or have different lengths on the different planes.

According to a further embodiment variant of this example, the channel arrangement has at least two plates which abut each other at their surfaces, wherein grooves defining the channel sections are formed on the surfaces in each case. In particular, a first plate has first grooves on a first surface, a second plate has second grooves on a second surface, and said second grooves run in a manner which corresponds to the first grooves, wherein the first surface of the first plate abuts the second surface of the second plate. A simple design format is thus realized for the channel arrangement. For example, by way of this format it is also possible advantageously to realize a channel arrangement having channel sections on a plurality of planes. The plates can be made of a plastic material such as e.g. PMMA (polymethyl methacrylate), glass or other material which is largely transparent to X-radiation.

According to both the first embodiment of the invention and the second example of the disclosure, the channel sections of the channel arrangement of the filter device can have in particular a diameter in a range between 50 μm and 5 mm, preferably between 500 μm and 3 mm. The cross-sectional shape of the channel sections can be circular. If the cross-sectional shape is not circular, the diameter of the channel section is understood to be the diameter of a circle which has the same cross-sectional area as the respective channel section.

According to a second embodiment of the invention, provision is made for an X-ray apparatus. The X-ray apparatus comprises an X-ray source for generating and emitting X-radiation in a beam path, an X-ray detector which is arranged in the beam path, and a filter system according to the first embodiment, wherein the filter device is arranged in the beam path between X-ray source and X-ray detector. For example, the filter device can be arranged in the beam path in such a way that the channel sections extend transversely relative to the beam path.

According to a third embodiment of the invention, provision is made for a method for locally changing the intensity of X-radiation. The method can be performed in particular using a system according to the first embodiment of the invention and an X-ray apparatus according to the second embodiment of the invention. The method comprises generating predetermined sequences of drops from a 2-phase fluid flow containing drops of an absorber liquid which absorbs X-radiation and a carrier liquid that is transparent to X-radiation, and supplying said drop sequences into channel sections of a channel arrangement of a filter device which is arranged in a beam path between an X-ray source and an X-ray detector, wherein the channel arrangement has a multiplicity of channel sections extending parallel to each other on a plane. The advantages cited in respect of the system and the X-ray apparatus apply to the method likewise.

According to a further example, provision is made for a filter system for the attenuation of X-radiation, comprising a filter device, which is arranged in the beam path of an X-ray apparatus and has two plates that are arranged parallel to each other and define an intermediate space, and a supply device for providing a 2-phase fluid flow containing drops of an absorber liquid that absorbs X-radiation and a carrier liquid that is transparent to X-radiation, said supply device being connected to the intermediate space. The filter system optionally also comprises a sorting section with an input that is connected to the supply device, a first output that is connected to the intermediate space, a second output, and a deflection device for directing individual drops of the absorber liquid to the first output or the second output. The optional sorting section and the supply device can be developed as described above.

According to this example, it is intended to distribute the drops of absorber liquid in the intermediate space between the plates by way of electrowetting. For the purpose of transporting the drops of absorber liquid in the intermediate space, an electrode arrangement can have e.g. a multiplicity of first electrodes which are arranged in the form of a matrix or an array on one of the plates and are electrically insulated from the absorber liquid, e.g. by virtue of the plates being made of electrically insulating material and the electrodes being fastened to an outer surface of one of the plates. The first electrodes apply a first electrical potential to the plate. One or more second electrodes are arranged in the intermediate space and apply a second electrical potential to the drops of absorber liquid. A switch device connects the individual first electrodes consecutively to an electrical voltage source, whereby transportation of the drops of absorber liquid within the intermediate space is achieved.

A concept underlying this example resides in distributing the drops of absorber liquid in the manner of pixels over a surface, by transporting and arranging them within an intermediate space that is formed between two plates by way of electrowetting. The carrier fluid here can take the form of an electrolytic liquid, for example.

FIG. 1schematically shows an X-ray apparatus200. The X-ray apparatus200has an X-ray source210for generating and emitting X-radiation in a beam path215, an X-ray detector220which is arranged in the beam path215, and a filter system1for the local attenuation of the X-radiation. As further illustrated schematically inFIG. 1, the filter system1has a filter device2, a supply device4and an optional sorting section3. The filter device2is arranged in the beam path215between the X-ray source210and the X-ray detector220. As symbolically illustrated by the arrow A1inFIG. 1, the X-radiation generated by the X-ray source210penetrates the filter device2first, followed by a patient P and then strikes the X-ray detector220. The filter device2serves to attenuate the X-radiation locally, in order to irradiate different regions of the patient P with a different radiation intensity.

FIG. 2shows the filter system1as a schematic block diagram or a simplified hydraulic flow diagram.FIG. 3shows a hydraulic flow diagram of the filter system with a greater level of detail. As illustrated inFIG. 2, the filter system1comprises a filter device2, a supply device4and an optional sorting section3.

The filter device2has a planar channel arrangement20with a multiplicity of channel sections21extending parallel to each other on a plane. As illustrated schematically inFIG. 1and as shown by the directional cross A1inFIG. 1, the filter device2can be arranged in particular in the beam path215in such a way that the channel arrangement20extends transversely relative to the beam path215.

An example channel arrangement20is illustrated in plan view inFIGS. 2, 3 and 5. It can be seen inFIG. 5in particular that the parallel channel sections21of the channel arrangement20can be connected to each other at their ends via connecting sections22, these being e.g. U-shaped, such that a continuous channel is formed. The channel arrangement20can therefore be developed as a continuous channel of parallel, preferably straight, channel sections21and connecting sections22in the form of an planar meander.

FIG. 6shows a schematic sectional view of a meandering channel arrangement20. As illustrated by way of example inFIG. 6, the channel sections21can each have a circular cross section. A diameter d21of the channel sections21can generally lie between 50 μm and 5 mm. As further illustrated by way of example inFIG. 6, a first group of the channel sections21of the channel arrangement20is arranged on a first plane E1, a second group of the channel sections21of the channel arrangement20is arranged on a second plane E2, a third group of the channel sections21of the channel arrangement20is arranged on a third plane E3, a fourth group of the channel sections21of the channel arrangement20is arranged on a fourth plane E4, and a fifth group of the channel sections21of the channel arrangement20is arranged on a fifth plane E5. The planes E1-E5extend parallel to each other here. In general, provision can be made for one or more further groups of channel sections21which are arranged in each case on planes E2-E5that are parallel to the first plane E1. In this context, the channel sections21of one plane can optionally be so arranged as to be offset relative to the channel sections21of the adjacent planes, in a direction transverse to the longitudinal extent of the channel sections21. The channel sections21within each plane E1-E5are connected via connecting sections22as illustrated by way of example inFIG. 5. It is optionally also possible to provide for a given channel section21of one plane to be connected via a connecting section22to a channel section21of a further plane, thereby forming a channel which extends continuously on all planes E1-E5.

The channel sections21and, if applicable, connecting sections22can take the form of tubes of plastic material as illustrated schematically inFIGS. 5 and 6by way of example. Alternatively, it is also conceivable for the channel arrangement20to be formed by at least two plates25which abut each other at their surfaces25a,25b, wherein grooves26defining the channel sections21are formed on the surfaces25a,25bin each case, as illustrated by way of example inFIG. 9and explained in detail below.

As illustrated by way of example inFIGS. 7 and 8, the channel sections21of the channel arrangement20can also be formed by individual channels23in each case. It can be seen inFIG. 7in particular that the channel sections20are formed by channel structures, e.g. separate tubes or lines, which run in parallel on a plane and are not interconnected.FIG. 8shows a sectional view of the channel arrangement20which is illustrated schematically and purely by way of example inFIG. 7. As illustrated inFIG. 8by way of example, the channel sections21can have a circular cross section in each case. A diameter d21of the channel sections21can generally lie between 50 μm and 5 mm. As further illustrated inFIG. 8by way of example, a first group of the channel sections21of the channel arrangement20is arranged on a first plane E1, a second group of the channel sections21of the channel arrangement20is arranged on a second plane E2, a third group of the channel sections21of the channel arrangement20is arranged on third plane E3, a fourth group of the channel sections21of the channel arrangement20is arranged on a fourth plane E4and a fifth group of the channel sections21of the channel arrangement20is arranged on a fifth plane E5. The planes E1-E5extend parallel to each other here. In general, provision can be made for one or more further groups of channel sections21which are arranged in each case on planes E2-E5that are parallel to the first plane E1. In this context, the channel sections21of one plane can optionally be so arranged as to be offset relative to the channel sections21of the adjacent planes, in a direction transverse to the longitudinal extent of the channel sections21.

FIG. 9shows an example truncated sectional view of a channel arrangement20which has three plates25in total. The channel arrangement20shown by way of example has a first group of channel sections21which are arranged on a first plane E1, and a second group of channel sections21which are arranged on a second plane E2. In general, for a quantity of n groups of channel sections21on n planes, a quantity of n+1 plates25is provided. As illustrated by way of example inFIG. 9, grooves26extending in parallel are formed on a lower surface25bof a first plate25A. The lower surface25bof the first plate25A abuts an upper surface25aof a second plate25B, wherein grooves26are formed on the upper surface25aof the second plate25B, running in a manner which corresponds to the grooves26of the first plate25B. The grooves26therefore face each other and together define the cross section and the longitudinal extent of the channel sections21. In the case of the channel arrangement20illustrated by way of example inFIG. 9, the second plate25B has further grooves26on a lower surface25b, which is oriented in the opposite direction to the upper surface25a. The lower surface25bof the second plate25B abuts an upper surface25aof the third plate25C, wherein grooves26are formed on the upper surface25aof the third plate25B, running in a manner which corresponds to the grooves26of the first plate25B. Therefore the channel arrangement20generally has at least two plates25which abut each other at their surfaces25a,25b, wherein grooves26that define the channel sections21are formed on the surfaces25a,25bin each case.

FIG. 10shows an example plate25, which can constitute e.g. the central plate25B fromFIG. 9. As illustrated by way of example inFIG. 10, the plate25can be embodied with a flat surface25aat edge sections that are opposite each other in a transverse direction running transversely to the longitudinal extent of the grooves26. This makes it easier to secure the plates25to each other, e.g. by way of bonding or adhesion. The plates25can be made of in particular a plastic material such as e.g. PMMA (polymethyl methacrylate), glass or other material which is largely transparent to X-radiation.FIG. 11shows a magnified detail view of the plate25shown inFIG. 10. It can be seen inFIG. 11in particular that the grooves26on opposite surfaces25a,25bof a respective plate can be so arranged as to be offset relative to each other in a direction transverse to their longitudinal extent.

The supply device4serves to provide a 2-phase fluid flow containing drops D of an absorber liquid that absorbs X-radiation, e.g. mercury or Galinstan, and a carrier liquid that is transparent to X-radiation, e.g. oil, in particular silicone oil.FIG. 3shows a possible layout of the supply device4by way of example. The supply device4illustrated by way of example inFIG. 3has a first reservoir41, a second reservoir42, a drop generator6, and an optional transport device5with a first pump51and a second pump52.

The absorber liquid is stored in the first reservoir41. The carrier liquid is stored in the second reservoir42. The first and second reservoirs41,42are each connected to the drop generator6in a fluidically conductive manner. In particular, the first pump51is arranged in a hydraulic path between the first reservoir41and the drop generator6, and the second pump52is arranged in a hydraulic path between the second reservoir42and the drop generator6, in order to transport the liquids from the reservoirs41,42to the drop generator6. It is optionally also possible for controllable valves (not shown), e.g. magnetic valves, to be arranged between the pumps51,52and the drop generator6.

As schematically illustrated inFIG. 3, the drop generator6has a first input61, a second input62and an output63. The first input61is connected to the first reservoir41, and the second input62to the second reservoir42. The output63is connected to an input30of the sorting section3.FIG. 4shows a drop generator6which is realized as a T-piece by way of example. The drop generator6in this case has a first line section61A comprising the first input61and second line section62A comprising the second input62. As illustrated schematically inFIG. 4, the first line section61A merges transversely, preferably perpendicularly, into the second line section62A. Since the absorber liquid and the carrier liquid cannot be mixed, the absorber liquid is cut off as a result of introducing the carrier liquid from the second line section62A into the first line section61A. By activating the pumps51,52and/or optionally the valves in a corresponding manner, it is possible to generate a periodic sequence of drops of absorber liquid and carrier liquid in a simple manner. The drop generator6therefore represents a device for generating a predetermined drop sequence.

As an alternative to a drop generator6, the supply device4can also have a reservoir41containing an emulsion of drops of the absorber liquid and the carrier liquid. The reservoir41can be connected to the input30of the sorting section3via the first pump51, e.g. in a similar manner to the first reservoir41. In order to produce a stable emulsion, a stabilizer such as e.g. PEG (polyethylene glycol) or silicone oil from which oxygen has been removed can be added to the carrier liquid.

The optional sorting section3is schematically illustrated inFIG. 3. The sorting section3has an input30, a first output31, a second output32and a deflection device35. The input30of the sorting section3is connected to the supply device4, e.g. to the output63of the drop generator6as illustrated by way of example inFIG. 3or directly to the reservoir41if an emulsion of drops of the absorber liquid and the carrier liquid is stored in the reservoir41. The first output31is connected to an input20A of the channel arrangement20. In the case of the filter system1illustrated by way of example inFIG. 3, the channel arrangement20takes the form of a continuous meandering channel as explained above with reference toFIG. 5. Provision is therefore made for only one sorting section3, whose first output31is connected to the continuous channel. The second output32can be connected in particular to a separator44(illustrated only symbolically inFIG. 3), which is designed to separate the absorber liquid from the carrier liquid and is connected to both the first and the second reservoir41,42. An output20B of the channel arrangement20can likewise be connected to the separator44as shown inFIG. 3by way of example. A closed circuit is realized thereby, in which the 2-phase fluid flow can be transported.

In the case of the channel arrangement20illustrated by way of example inFIG. 7, in which the channel sections21are realized by individual channels23, each channel section21or channel23is provided with a respective sorting section3whose first output31is connected to an input of the respective channel23. The second outputs32of the sorting sections3can each be connected to the separator44in a similar manner to the example illustration inFIG. 3.

The deflection device35serves to direct individual drops D of the absorber liquid to the first output31or the second output32. In this way, each channel section21can be supplied with a specific sequence of drops D of absorber liquid and carrier liquid. As illustrated by way of example inFIG. 3, the deflection device35can have a first electrode36and a second electrode37arranged opposite thereto, in order to generate an electrical field for deflecting the drops in a separation section38which extends between the input30and the outputs31,32of the sorting section3. As illustrated schematically inFIG. 3, the electrical field generated via the electrodes provokes a directional change in the movement of the drops D of absorber liquid, such that these are directed either to the first output31and therefore into the channel arrangement20or to the second output32and therefore optionally via the separator44back into the first reservoir41. The deflection device35is generally designed to apply a force to the drops D, said force being transverse to the direction of flow. The sorting section therefore represents a further device for generating a predetermined drop sequence, and can be used alone or in combination with the drop generator6.

For the purpose of locally changing the intensity of the X-radiation, the filter device2is arranged in the beam path215of the X-ray apparatus200as illustrated by way of example inFIG. 1. The sorting section3and/or the drop generator6is used to generate a predetermined sequence of drops D of the 2-phase fluid flow provided by the supply device4. The drop sequences are then transported into or supplied to the channel sections21of the channel arrangement20, e.g. via the hydraulic pressure that is generated by the pumps51,52or by way of electrowetting by an electrode arrangement that is provided at the channel sections21. It is alternatively also conceivable to transport the drop sequences by way of electrostatic forces generated by electrodes (not shown) that are provided at the channel sections21. By introducing sorted sequences of drops of absorber liquid and drops of carrier material into the channel sections21, it is possible to achieve an attenuation of the radiation at discrete points at which the drops of absorber liquid are arranged.FIG. 7shows an arrangement of drops D of absorber liquid by way of example. The regions lying between the drop sequences are filled with carrier liquid, such that the X-radiation is attenuated only slightly or not at all in these regions.

The optional sorting device3can provide various sequences of drops in an efficient manner. The channel structure20has a simple design format and can advantageously be filled and emptied quickly, e.g. by flushing with carrier liquid. By virtue of their planar extent, a type of pixel pattern for locally resolved attenuation of the radiation can be generated by the drops of absorber material. The optional provision of a plurality of groups of channel sections21, which are arranged on different planes E1-E5, additionally allows the degree of attenuation to be adjusted individually for each pixel.

FIG. 12shows a further filter system100. The filter system100comprises a filter device102with a channel arrangement120, a reservoir140with an absorber liquid F that absorbs X-radiation, and a transport system150.

FIG. 13shows a plan view of the channel system120. It can be seen inFIG. 13in particular that the channels123are formed by channel structures running in parallel on a plane, e.g. by separate tubes or lines which are not interconnected. Each channel123extends between a first end123A and a second end123B which is positioned opposite thereto.

FIG. 14shows a sectional view of the channel arrangement120which is illustrated schematically and purely by way of example inFIG. 13. As illustrated by way of example inFIG. 14, the channels123can have a circular cross section in each case. A diameter d123of the channels123can generally lie between 50 μm and 5 mm. As also illustrated by way of example inFIG. 14, a first group of the channels123of the channel arrangement120is arranged on a first plane E1, a second group of the channels123of the channel arrangement120is arranged on a second plane E2, a third group of the channels123of the channel arrangement120is arranged on a third plane E3, a fourth group of the channels123of the channel arrangement120is arranged on a fourth plane E4and a fifth group of the channels123of the channel arrangement120is arranged on a fifth plane E5. The planes E1-E5extend parallel to each other here. In general, provision can be made for one or more further groups of channels123which are arranged in each case on planes E2-E5that are parallel to the first plane E1. In this context, the channels123of one plane can optionally be so arranged as to be offset relative to the channels123of the adjacent planes, in a direction transverse to the longitudinal extent of the channels123, as illustrated by way of example inFIG. 14. The individual channels123can be realized via plates25with grooves26which are formed therein, e.g. as illustrated inFIG. 9and explained above.

The reservoir140inFIG. 12is illustrated merely symbolically as a block and contains an absorber liquid which absorbs X-radiation, e.g. Galinstan or mercury. For example, an electrolyte can be added to the absorber liquid. The reservoir140is connected to the channel arrangement120in a fluidically conductive manner, e.g. via a line system, each channel123being connected to the reservoir140at both the first end123A and the second end123B.

As schematically illustrated inFIG. 12, the transport system150can take the form of an electrode arrangement. In the filter system100illustrated by way of example inFIG. 12, the electrode arrangement has a multiplicity of first electrodes151and at least one second electrode152per channel123. For each channel123, a multiplicity of first electrodes151are so arranged as to be distributed along the channel123, e.g. fastened to an outer surface of the channels123, in order to apply a first electrical potential to the channel walls. The first electrodes151are electrically insulated from the absorber liquid, e.g. by virtue of the channels123being made of an electrically insulating material. For each channel123, at least one second electrode152is arranged in the interior of the respective channel123and applies a second electrical potential to the absorber liquid F.

A switch device153is electrically connected to the first electrodes151or is designed to connect each of the first electrodes151individually to an electrical voltage source154and optionally to control the electrical potential of the first electrodes151. The switch device153is optionally also connected to the second electrodes152, in order to control their electrical potential. Alternatively, the second electrodes152can also be coupled to a ground potential. The switch device153is designed to connect the individual first electrodes153consecutively to the voltage source154, whereby transportation of the absorber fluid along the channels is achieved.

Alternatively, the transport system150can also be realized via a hydraulic system. The hydraulic system comprises at least one pump, which is arranged between the reservoir123and the channel arrangement120in order to fill the channels123from two sides with a specific occupancy level of absorber liquid F. A hydraulic system comprising a first pump158, which is arranged between the reservoir140and the first ends123A of the channels123, and a second pump159, which is arranged between the reservoir140and the second ends123B of the channels123, is illustrated inFIG. 12by way of example. It is also conceivable to provide one or two dedicated pumps for each of the channels123. Alternatively or additionally, valves can be provided in order to control the occupancy level of absorber liquid in the channels.

Although the invention is illustrated and described in detail by the example embodiments above, the invention is not restricted by the examples disclosed therein, and other variations may be derived therefrom by a person skilled in the art without thereby departing from the scope of the invention.