Static computed tomography system and detector arrangement

Abstract

Computed tomography system comprising an examination area (2) and a static gantry (3), comprising a base frame (4), an annular detector arrangement (6) with detector elements and an annular X-ray source arrangement (5) with X-ray sources, each of which at least partially encloses the examination area (2) and has a substantially common axial direction, wherein the detector arrangement (6) and the X-ray source arrangement (5) are attached or attachable to the base frame (4) from different sides in axial direction, wherein the computed tomography system comprises at least one guide rail (10) which runs essentially in the axial direction and with which an offset of the detector arrangement (6), in particular of individual detector segments (61) of the detector arrangement (6), can be guided in the axial direction, wherein the computed tomography system comprises at least one eccentric disc (45) for installing the detector arrangement (6) in conjunction with at least one guide rail (10).

Description

The invention relates to a computed tomography system.Regardless of the grammatical sex of a certain term, individuals with male, female or other sex identity are included.Computed tomography (CT) systems known in the art typically include an x-ray tube and a detector opposite the x-ray tube. For imaging on a patient, the x-ray tube and detector rotate about the patient. A three-dimensional image of the patient can be acquired by the rotation.As prior art, U.S. Pat. No. 6,731,716 B2, GB 2 019 688 A, U.S. Pat. No. 4,274,005 A, DE 24 62 538 A1 and KOWTAL, A. [et al.] Signal Sensing and Reconstruction Paradigms For a Novel Multi-Source Static Computed Tomography System. Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2020.However, the rotation can also entail disadvantages. Due to the rotation, the requirements for the mechanics of the CT system and the realization of the data transmission (concerning, e.g., correspondingly flexible interfaces) are relatively great. These increased requirements result in increased manufacturing and maintenance costs and generally increased costs and may also impair image quality.For example, there is the risk that vibrations are generated by the rotation, which vibrations can cause disturbing frequencies in the measurement signals and thus artifacts in CT images. Rotation in general and vibrations caused by rotation in particular may result in a more rapid wear of the components. Furthermore, due to the rotation, it may be necessary for components to be manufactured particularly massively, since a deformation of the components may have a great influence on the image quality. A particularly slender design of the CT system is thus generally not possible. This ensures increased space requirement and higher hardware costs. This also limits the possible fields of application of the CT systems. For example, application in the intraprocedural area or for CT Linac concepts with real-time imaging in an irradiation isocenter is difficult to implement. In addition, the use of the CT system is generally possible exclusively for stationary use. CT systems are thus rather not suitable for use in the mobile sector (e.g. in the hospital truck). The rotation also makes the data transmission more difficult, for example via sliding contacts, as a result of which the capacity of the data transmission can also be limited.It is therefore an object of the present invention to provide a computed tomography system with which the disadvantages indicated can be addressed and at least partially improved. In particular, a computed tomography system is desirable which can be used flexibly, in particular by a lower weight and / or by reducing or avoiding rotational forces. Furthermore, a possibility for the precise and as simple as possible alignment and installation of the components of the computed tomography system is desirable.This object is achieved by a computed tomography system according to claim 1.According to a first aspect of the invention, a computed tomography system is provided, comprising an examination region and a gantry, in particular a static gantry. The gantry comprises a basic framework, an annular detector arrangement with detector elements and an annular x-ray source arrangement with x-ray sources, which each at least partially enclose the examination region and have a substantially common axial direction. The detector arrangement and the X-ray source arrangement are attached or attachable to the basic structure from different sides as seen in the axial direction.The term examination region is to be understood broadly within the scope of this invention. The examination region is generally a region in which a subject or object or a part of a subject or object can be placed in order to examine it with the computed tomography system, in particular in order to collect image data therefrom. The subject may be, for example, a human, in particular a patient, or an animal. An object may be, for example, part of a human or animal, e.g. a limb, a torso, an organ, etc. An object may, however, also be any other object, e.g. any object. It is conceivable, for example, to use the computed tomography system for medical examinations or examinations in humans. However, other purposes, such as examining pieces of luggage or material examinations, are also conceivable.The gantry is preferably arranged around the examination region. The term "static gantry" is to be understood in particular in contrast to a rotating gantry according to the prior art. The term "static" refers to the use in a CT measurement. The gantry is configured in particular such that it does not have to be rotated for a CT measurement or that it is not provided that the gantry rotates substantially around the examination region during the CT measurement. This is made possible by the detector arrangement and the X-ray source arrangement being provided annularly. The ring-shaped arrangement and the plurality of detector elements and X-ray sources make it possible in particular to achieve 360° image recording (for example by selective successive activation and deactivation of the X-ray sources). Thus, even without rotation of detector and X-ray source, measured values from different solid angles can be generated. Moreover, it is not excluded that the static gantry can also be generally rotatable, for example in the uninstalled state or during installation of the gantry. The gantry can be, in particular, a short annular tunnel. The axial direction of the ring tunnel can substantially correspond to the axial direction of the detector arrangement and of the X-ray source arrangement. The axial direction can also be referred to as the z-direction. The term "substantially" is to be understood in this context such that certain, for example structurally related, deviations may also be present. Preferably, however, the axial directions of the respective mentioned components, in particular of the detector arrangement and the X-ray source arrangement, do not deviate from one another by more than 10°. In this context, a radial direction is to be understood such that it runs perpendicular to the axial direction and in particular runs radially outwards from a center point of the respective rings. Accordingly, the term radial direction is to be understood to mean that there are a plurality of directions corresponding to a radial direction, namely according to the totality of the possible radially extending directions. The radial direction can also be referred to as the x-direction, y-direction and / or x,y-direction.Advantageously, the computed tomography (CT) system can be designed to be relatively narrow compared to third generation CT systems customary in the prior art. This can be achieved in that a rotation of the gantry, which is static, does not have to be provided for a CT examination and thus a less stable, lighter construction is possible. Machine dynamics aspects typically need not be taken into account in the mechanical design. As a result, in particular, the basic frame of the gantry can also be made narrower, because it does not have to withstand any rotational forces. Moreover, wear effects caused by rotation can be largely avoided.For example, it may be possible for a system according to the invention to be designed for a mobile application as well. Advantageously, no usually complex and expensive interfaces between parts moved relative to one another, such as sliding contacts, or via capacitive transmission, are required either. Rotation-induced vibrations and interference frequencies and artifacts resulting therefrom in the measurement data and wear which occurs can also be avoided. Furthermore, it may advantageously be possible to record images more quickly and to be more flexible in the selection of successive recording angles, because no inertia during mechanical rotation has to be taken into account. A comparatively higher temporal resolution is also conceivable in principle.The gantry comprises a basic frame. The basic framework is in particular configured such that the detector arrangement and the X-ray source arrangement can be attached thereto. The term "backbone" is to be broadly understood herein. The backbone preferably comprises an annular portion. In particular, the annular section at least partially encloses the examination region. The basic framework is preferably designed to ensure a safe state of the computed tomography system. The basic framework can comprise a foot region which is designed to enable the gantry to be set up. The foot region can be connected indirectly or directly to the annular section of the basic structure. For example, the foot region can be connected to the annular section and / or the annular section can merge into the foot region. The foot region can have an extension in the axial direction. For example, the foot region can have two extensions in the axial direction. The extensions can be configured to stand on a planar base. As viewed in the axial direction, the root portion may have a straight termination in one direction and an annular portion receiving portion opposite to the straight termination. Preferably, the straight termination may be tangential to the annular portion. The basic structure can have interfaces, in particular electronic interfaces for supplying and / or controlling and / or for reading out components of the computed tomography system. For example, the basic structure can have interfaces for the detector arrangement.The gantry comprises the annular detector arrangement. The detector arrangement is preferably a static detector arrangement corresponding to the static gantry. In particular, the detector arrangement is configured not to rotate about the examination region during a CT measurement. This has the advantage that fewer rotational forces occur, as a result of which the gantry can be designed to be less massive overall. This makes it possible to save material and the CT system can be lighter overall. The term "ring-shaped" is to be broadly understood. For example, the detector arrangement can have an extension in the radial direction. The detector arrangement can be a 360° detector ring. Accordingly, the detector ring extends around the entire circumference of a circle. This is advantageous in that x-ray signals can thus be detected in all radial directions. Alternatively, the detector arrangement can also be a partial ring. A partial ring does not extend over the entire circumference of a circle. For example, the partial ring may relate to a fan angle of 160° to 300°. This can be advantageous, for example, in order to provide a particularly light or particularly favorable CT system. The detector arrangement encloses the examination region at least partially, that is to say in particular that the detector arrangement is arranged around the examination region. The term at least partially may be understood here and with respect to the other components such that the detector array (or corresponding other component) may be a complete ring or a partial ring. Alternatively or additionally, it can also be related at least partially to the examination region extending beyond the physical extent of the detector arrangement in the axial direction. The detector elements can be distributed around the examination region in accordance with the annular detector arrangement. Preferably, the detector elements can be distributed around the examination region at uniform distances.The computed tomography system comprises an annular x-ray source arrangement. The X-ray source arrangement is preferably a static X-ray source arrangement corresponding to the static gantry. In particular, the X-ray source arrangement is configured not to rotate about the examination region during a CT measurement. In this regard, the same advantages and properties can be analogously applicable as for the detector arrangement and the basic structure. The x-ray source arrangement comprises a plurality of x-ray sources. The X-ray sources can be distributed around the examination region in accordance with the ring-shaped X-ray source arrangement. Preferably, the X-ray sources can be distributed around the examination region at uniform distances. The x-ray source arrangement can be a 360° x-ray source ring. Accordingly, the x-ray source ring extends around the entire circumference of a circle. This is advantageous in that x-ray signals can thus be emitted in all radial directions. Alternatively, the x-ray source arrangement can also be a partial ring. For example, the partial ring may relate to a fan angle of 160° to 300°. The X-ray sources may optionally be based on a nanotube field emission technique. X-ray sources based on field emission have the advantage over x-ray sources which are usually used in CT systems of the prior art and are based on heat-induced emission that a more rapid switching can be made possible, since an after-glow effect can be avoided to the greatest extent possible. The x-ray source arrangement may be configured to activate individual or groups of a plurality of its x-ray sources one after the other during a CT scan of a subject or object in the examination region.The detector arrangement and the X-ray source arrangement are attached or attachable to the basic structure from different sides as seen in the axial direction. In particular, the detector arrangement and the X-ray source arrangement can be attached or attachable to the basic structure from opposite sides. For example, the detector arrangement can be mounted on the basic structure from a positive axial direction (or from a +z direction) and the X-ray source arrangement can be mounted on the basic structure from a negative axial direction (or from a -z direction). By mounting different sides, on the one hand, a particularly good spatial distribution of the components can be possible. In particular, a clear interface separation can take place between the X-ray source arrangement and the detector arrangement. Corresponding connections can be provided, for example, on the respective outer side. The X-ray source arrangement and the detector arrangement can thereby be provided very close to one another. As a result, an inclination of the X-rays can in turn be reduced, as a result of which artifacts caused by an inclination ("cone beam effect") can be reduced. This can enable a particularly compact gantry and thus a particularly compact and space-saving CT system. On the other hand, a particularly good accessibility of the two components, x-ray source arrangement and detector arrangement, can be made possible individually in each case. This may be advantageous for replacement and maintenance purposes, for example. For example, the detector arrangement can be able to be dismounted or partially dismounted without the X-ray source arrangement making the dismounting substantially more difficult. For example, the detector arrangement can thus be directly accessible and able to be dismounted, wherein for this purpose, for example, only one cover plate has to be removed.According to one embodiment, the computed tomography system further comprises a patient couch. The patient bed can be movable, in particular also during a CT examination. The patient bed can be retractable and extendable in the axial direction into the gantry. The detector arrangement can be attached or attachable to the basic frame from the side of the patient couch in the axial direction. By attaching the detector arrangement from the side of the patient couch, particularly easy access to the detector arrangement, for example for maintenance purposes, can be made possible. In particular, the detector arrangement or elements of the detector arrangement can be removed from the gantry in a particularly simple manner. Optionally, however, it is also conceivable for the detector arrangement to be attached or attachable to the basic framework on the other side, facing away from the access of the patient couch.According to one embodiment, the detector arrangement comprises at least two separate or separable detector segments each having at least one detector element. Each of the detector segments may preferably comprise one or more detector elements configured to detect X-rays. The division of the detector arrangement into detector segments can advantageously simplify handling of the detector arrangement, for example by requiring less large parts to be moved during installation. Costs, for example during transport, can also be reduced as a result. Furthermore, modularization can be made possible by dividing into detector segments. For example, individual detector segments can be exchanged. Furthermore, detector segments make it possible to achieve better fine adjustment of the positioning of the individual detector sections. The detector arrangement can preferably comprise 2 to 10, particularly preferably 2 to 5, detector segments. This number can be particularly advantageous in that the number of parts to be manipulated can still be monitored and at the same time a certain flexibility is made possible. For example, the detector arrangement can comprise exactly three detector segments. Three detector segments can be particularly favorable both for a relatively simple installation due to the lower weight and for a simple alignment due to the flexibility obtained. It has been found that three detector segments on the one hand enable a flexible adaptation of the alignment of the detector segments, but on the other hand also a good stability and organization of the individual parts by using not too many segments. However, it is also possible in principle for the detector arrangement to comprise more than three detector segments or exactly two detector segments or exactly one detector segment.According to one embodiment, the detector segments are essentially ring segments, which each form a partial ring of the detector arrangement. Ring segments can be particularly favorable in that they can directly enable enclosing the examination region. The ring segments can have, for example, an angle size of 5° to 355°, preferably 15° to 270°, particularly preferably 30° to 180°. Most preferably, the ring segments can have an angle size of 100° to 150°. Preferably, the angle sizes may have a substantially uniform angle size.A specific, particularly preferred example is ring segments with an angle size of essentially 120° in each case.According to one embodiment, the computed tomography system is configured such that a positioning of the individual detector segments in the axial direction of the detector arrangement is adjustable. For example, the position of the individual detector segments can be individually adjustable in the axial direction. Advantageously, the position of the detector arrangement as a whole can, however, also be adjustable with respect to the individual detector segments. Adapting the entire detector arrangement may be helpful in adjusting the positioning with respect to one or more X-ray sources. It can thus be achieved, for example, that the detector arrangement is located at the focal point of the X-ray source(s). By adjusting the individual detector segments, it is also possible to advantageously compensate for non-uniformities in the structure of the gantry of the X-ray source(s) or of the detector arrangement. Optionally, an alignment of the detector segments can also be adjustable. An even more accurate adaptation of the detector arrangement can thus be possible. The computed tomography system can preferably be configured such that the detector segments can be fixed after the axial position has been adjusted.According to one embodiment, the detector arrangement comprises a base plate and at least one functional unit which is fastened or can be fastened to the base plate and can be removed from the base plate. In particular, the detector segments of the detector arrangement, as described herein, can each comprise a base plate and at least one functional unit which is fastened or can be fastened to the base plate and can be removed from the base plate. The functional unit or at least one of the functional units can be a modular unit with at least one of the detector elements. The detector arrangement can optionally comprise further functional units. Individual functional units can comprise or be modules, cables and / or a DSF data streaming front end), for example. The base plate can have an opening and / or recess which is designed such that the module unit can be accommodated or passed through it. For example, functional units can be or comprise control and / or read-out electronics for the detector elements. The base plate can be substantially partially annular or annular.If detector segments are provided, the base plate can preferably be partially ring-shaped. The base plate, viewed in the axial direction, can define the outer shape of the detector segments by its own shape. Advantageously, the base plate enables a particularly good modular and flexible configuration of the detector arrangement. The term base plate is to be understood broadly here. In particular, the base plate does not have to be flat, but can have a structured surface. For example, the base plate can have means for receiving and / or fastening the functional units. Advantageously, the base plate can make it possible to remove individual functional units, for example individual modular units with detector elements, for example for maintenance or replacement, without changing the general alignment of the detector segment, in that the base plate remains in the installed and aligned state.According to one embodiment, the detector arrangement comprises at least one housing section, wherein the housing section is configured such that at least one of the functional units can be inserted at least partially into the housing section.In particular, the housing section can be provided for at least one module unit with in each case at least one of the detector elements. It can be provided that the at least one functional unit is inserted in the housing section during the operation of the CT system. It can be provided that the functional unit is removed or removable from the housing for maintenance of the functional unit. Preferably, the housing section can be annular or partially annular. The housing section can itself be a functional unit which can be fastened or fastenable in particular to a base plate as described herein. The housing section can be configured in particular such that the detector elements of at least one module unit can be inserted into the housing section. Advantageously, the detector elements can thus have a position defined by the position of the housing section. It may thus be possible to exchange detector elements without having to subsequently readjust their position or it may be possible in a simplified manner to adjust the position of the detector elements.It can be provided that a plurality of modular units with detector elements can be inserted or inserted in a housing section. For example, a housing section can be configured such that in each case two of the modular units can be inserted at least partially into the housing section. The employment of two module units in each case can be particularly advantageous in order to enable both a stable positioning and simple maintenance. The housing section can be connected to the base plate or designed to be attached to the base plate. The housing section can connect to an opening of the base plate. In particular, an opening of the housing section can connect to the opening of the base plate. The housing section can preferably be provided on a side of the base plate facing the X-ray source arrangement. It can be provided that the at least one module unit can be removed from the housing section through the opening of the base plate.Per module unit or for a plurality of module units, a terminating plate can be provided in each case, which is attached or can be attached to the base plate on a side of the base plate facing away from the X-ray source arrangement. The closure plate can be configured to at least partially close off the opening of the base plate. The end plate may include one or more end plate openings. The end plate openings can be provided, for example, for the purpose of allowing connections of control or read-out electronics of the detector elements to be carried through them. The connections of the control or read-out electronics of the detector elements can extend through the end plate openings at least in the assembled state. The connections can be, for example, connecting cables and / or plug connections. It can be provided that on a side of the end plate facing away from the base plate, the control or readout electronics of the detector elements of the detector elements are mounted and / or can be mounted. The term terminating plate is not necessarily to be understood as absolute in so far as further elements can follow terminating elements after the terminating plate. For example, a cover can also be provided behind the end plate or behind the control or read-out electronics. At least one spacer can be provided between the at least one module unit and the end plate. For example, one spacer piece can be provided per module unit. The at least one spacer may include at least one spacer opening. The at least one spacer opening can be provided for the purpose of allowing connections of the control or read-out electronics of the detector elements to be carried through them. The connections of the control or read-out electronics of the detector elements can extend through the at least one spacer opening at least in the assembled state.According to one embodiment, the detector arrangement comprises at least one functional unit comprising at least some components of control electronics for reading out the detector elements, wherein the functional unit is arranged offset in the axial direction with respect to the detector elements, in particular with respect to at least one module unit having the detector elements, on a side of the detector arrangement facing away from the basic structure. Advantageously, it can thus be achieved that the control electronics are not in the region between X-ray sources and detector elements. As a result, the X-ray sources and detector elements can be brought together more closely as viewed in the axial direction. This enables a better image quality and an even more compact construction to be achieved. The functional unit may comprise an electronic cover. Preferably, the control electronics are arranged between the base plate and the electronics cover. The electronics cover is preferably at least partially metallic and / or conductive. A metallic or conductive configuration can allow shielding against interference signals or interference radiation. For example, the electronics cover can be made of noble metal or comprise noble metal.According to one embodiment, the X-ray source arrangement comprises a plurality of X-ray source segments. All advantages and features relating to the detector segments of the detector arrangement can be transferred analogously to the X-ray source arrangement. Thus, individual segments of the X-ray source arrangement can advantageously be removed. For example, corresponding functional units and / or housing sections of the X-ray source arrangement can also be provided. For example, 10 to 200, preferably 50 to 100, nanotubes per X-ray source segment can be provided.According to one embodiment, the computed tomography system comprises an annular aperture for the X-ray source arrangement. The diaphragm can preferably be mechanically decoupled. The aperture can be designed as a shaft aperture, in particular a deep shaft aperture. The diaphragm can in particular comprise diaphragm segments. The aperture can be arranged in front of the beam exit opening of the X-ray source arrangement. In particular, the aperture can be arranged in front of the beam exit opening such that the aperture collimates the X-rays of the X-ray source arrangement. It can be provided that the aperture can be manually adjustable. For example, the diaphragm can be adjustable with the aid of spacers. Additionally or alternatively, the aperture can be adjustable automatically, for example by means of a motor. The setting of the diaphragm can be supported by sensors, so that the diaphragm setting can be automatically improved by a sensor system.According to one embodiment, the computed tomography system is configured such that a positioning of the aperture in the axial direction is adjustable. The adjustability of the diaphragm and / or the diaphragm segments can be provided analogously as described with respect to the adjustability of the detector arrangement or the detector segments. The diaphragm can be fastened or can be fastened to the basic structure and / or to the X-ray source arrangement by at least one holder. The holder can be, for example, a fastening bracket. Preferably, a plurality of holders are provided. For example, 2 to 5 holders, particularly preferably 3 to 4 and very particularly preferably 3 holders, can be provided.According to one embodiment, the aperture comprises a shielding base plate made of a first material that shields X-rays, and segments made of a second material that shields X-rays arranged on the shielding base plate, wherein the second material has stronger X-ray shielding properties than the first material. The first and second materials may be joined by welding, for example. The segments can preferably be arranged circumferentially in the circumferential direction of the aperture. Optionally, additional stabilizing plates may be provided. The stabilizing plates can have, in particular, a radial main extension. The stabilizing plates can in particular run perpendicular to the segments of the second material. The second X-ray shielding material can be tungsten in particular. Tungsten has the advantage that it has very good shielding properties. The first X-ray shielding material can be, for example, lead, brass or copper. Copper or brass has the advantage of being more harmless to health than lead. Lead has the advantage that less material is required to achieve a sufficient shielding effect. For example, roll lead may be provided. Advantageously, the first material is softer than the second material. While tungsten can shield very well, it is very rigid and potentially brittle. In addition, tungsten is usually very expensive. By supplementing with the first material, a particularly good shielding by the second material (e.g. tungsten) can thus be achieved in a targeted manner, wherein a supplementary (somewhat weaker) shielding by the first (somewhat more favorable material) can be achieved at less critical locations. In addition, the first material can allow additional stability or breaking strength. Optionally, the shielding plate can have notches and / or a locally reduced wall thickness. With the notches or the reduced wall thickness, a lower weight of the panel can be achieved.According to one embodiment, the aperture comprises at least a first aperture part and a second aperture part, wherein the first aperture part is fastened to the detector arrangement or is an integral part of the detector arrangement. By fastening a diaphragm part to the detector arrangement, the detector arrangement can be arranged particularly close to the beam exit opening and an even more compact construction can be achieved. The second aperture part can preferably be attached to the x-ray source arrangement or another part of the gantry, e.g. the basic frame, or can each be an integral part thereof. The aperture can be a ring which is completely closed in the circumferential direction of the X-ray source arrangement or of the detector arrangement. The first aperture part and the second aperture part can together form a channel which limits the propagation of the X-ray radiation. The channel can extend in particular in the radial direction.The channel can, optionally, viewed in the circumferential direction of the circle, have a substantially constant cross section and / or a constant channel opening with respect to the jet outlet opening. Optionally, the first aperture member may be attached to the housing portion, for example, as described herein. It can thus preferably be prevented that a change of the position of the first aperture part takes place during the removal or the exchange of the module unit with the detector elements.According to one embodiment, the detector arrangement is designed such that it can be displaced together with the first aperture part in the axial direction, such that an aperture opening of the aperture can be adjusted by displacing the detector arrangement in the axial direction. This embodiment can represent an efficient way to realize different diaphragm openings for the X-ray sources. Advantageously, the position of the detector arrangement and the beam distribution can thus be adapted simultaneously. This may allow the propagation of the X-rays and the detector position to be synchronized easily and effectively.According to one embodiment, replaceable spacers are provided between the detector arrangement and the basic structure and / or between the X-ray source arrangement and the basic structure and / or between a diaphragm and the basic structure. A positioning of the detector arrangement and / or of the X-ray source arrangement and / or of the aperture in the axial direction can thus be adjustable with the spacers. For example, the spacers can be provided between a holder, which fixes the panel to the basic structure, and the basic structure. Additionally or alternatively, spacers can also be provided for adjusting the position in another direction, in particular in a radial direction. According to an embodiment, the computed tomography system comprises at least one dowel pin for adjusting the positioning of a component in a radial direction.According to one embodiment, exchangeable spacers are provided between the detector segments and the basic framework, so that the positioning of the detector segments in the axial direction of the detector arrangement with the spacers can be adjusted. The term spacer is to be understood broadly within the scope of this invention. Spacers may describe any means suitable for ensuring a distance between the basic frame of the gantry and the respective detector segment. Advantageously, the spacers can regulate the distance between a focal point of the X-ray sources of the scanning planes of the detector arrangement or of the detector elements in the axial direction. For example, it can be provided to release the detector arrangement or individual detector segments and to move them in the axial direction on the guide rails, as described herein. A new spacer can then be inserted on the basic structure and the detector arrangement or the detector segment can be moved back again in the axial direction until the detector arrangement or the detector segment has contact with the spacer. An adjustment of the detector arrangement can thus be effected particularly precisely and quickly. Additional manual adjustment steps that would otherwise be necessary can thus be omitted. The spacers additionally represent a particularly cost-effective possibility for enabling the detector segments to be adjusted in the axial direction. Optionally, it can be provided to use the spacers in order to clamp at least one of the detector segments, in particular at least one of the base plates, in order to compensate for a shape of the respective detector segment. This may be advantageous in particular in the case of distortions caused by heat.According to one embodiment, at least two spacers are provided for each of the detector segments. Advantageously, a plurality of spacers can also enable a particularly good adaptation of the alignment of the detector segments. Particularly advantageously, 3 to 5 spacers, preferably 4 to 5 spacers, can be provided per detector segment. This number of spacers can likewise allow stable installation of the detector segments, good variability in the alignment of the detector segments, and a manageable outlay in the fitting of the spacers.For example, the spacers can be compensating disks. For example, the spacers can be shim plates. Shim plates can also be defined as underlay plates and / or adjustment plates.According to one embodiment, the spacers are manufactured from a metal-containing material, in particular steel. The properties of metal can be particularly well suited for use as spacers. For example, a heat emission of the detector can be improved via metals, e.g. during operation-related heating (or corresponding to the other components, i.e. in particular the X-ray source arrangement or aperture). In particular steel can allow a good combination of flexibility in production and stability. Optionally, however, other materials are also conceivable for the spacers.According to one embodiment, the spacers are elongated shims. An orientation of the spacers is preferably provided such that the longitudinal extent of the compensating disks corresponds substantially to a radial direction. By orienting the longitudinal extension of the spacers in the radial direction, it can be made possible, for example, to change the flatness of the detector arrangement (or of the corresponding other component) particularly well or, if appropriate, to correct it.According to one embodiment, the basic structure comprises fastening means for fixing the spacers. Fasteners may simplify and / or more reliably facilitate installation of the spacers. The fastening means can comprise screw holes, for example. The fastening means can comprise, for example, slots for inserting the spacers. The attachment means may comprise, for example, a click & release mechanism. The backbone may comprise multiple attachment means for multiple spacers per detector segment.According to one embodiment, the computed tomography system comprises a set of spacers with different thicknesses. With a set of spacers, an axial position of the detector arrangement or of the detector segments (and / or corresponding to the other components) can be set or changed relatively quickly and easily. The change of the axial position can be effected, for example, simply by replacing or supplementing spacers.For example, the spacers can be provided in graduations of 0.01 to 0.5 mm, preferably 0.05 to 0.2 mm. Graduations in this region can be particularly useful for setting the positioning, in that, on the one hand, a precise setting is possible, but, on the other hand, too many spacers are also not required.According to one embodiment, the computed tomography system comprises at least one motor configured to adjust the positioning of the detector arrangement, the X-ray source arrangement and / or the aperture in the axial direction. Additionally or alternatively, the computed tomography system may comprise at least one motor configured to adjust the positioning of at least one of the detector segments in the axial direction. The computed tomography system can comprise a plurality of motors, each configured to adjust the positioning of at least one of the detector segments and / or further components of the gantry in the axial direction. The at least one motor, optionally a plurality of motors, can / can be configured to set the positioning of a plurality of, preferably all, the detector segments in the axial direction. Advantageously, an automatic adjustment of the axial position can be made possible with a motor. For example, the detector arrangement or the detector segments can / can be mounted on a guide rail as described herein and / or can be guidable on the guide rail. Advantageously, the engine can be configured to allow for substantially continuously variable adjustment of the axial position. "Substantially continuously variable" is understood to mean the accuracy possible due to design and due to other constraints (such as reasonable cost savings with which a certain accuracy can be achieved). The motor may be provided without using spacers. Optionally, the spacers may be combined with the motor as described herein. The spacers may, for example, enable additional positional stability, while the motor may simultaneously enable automatic displacement of the corresponding component.According to one embodiment, the motor is a linear drive and / or a spindle drive. The guide rail can optionally have a thread. The motor may comprise a shaft that drives the thread, such that by rotating the thread a displacement in the axial direction of the detector arrangement, the x-ray source arrangement, the aperture and / or the detector segment can be made possible. The motor can be arranged on the detector arrangement, the x-ray source arrangement, the aperture and / or the detector segment. The linear drive can comprise a linear unit and a servomotor, wherein the linear unit is driven via the servomotor. The linear unit can be the guide rail or correspond to the guide rail.The computed tomography system can have at least one, preferably a plurality of, contact surfaces which are designed to determine an orientation of the detector segments in a plane whose normal is the axial direction. The detector segments can have corresponding contact sections (or at least one contact section) for contact with the contact surfaces.According to one embodiment, the computed tomography system is configured to detect deviations from a positioning of the detector arrangement, in particular of the individual detector segments of the detector arrangement, classified as ideal, by means of a sensor system. Advantageously, the sensor system can be used to automatically determine whether a position of the detector arrangement or of the detector segments should be adapted. The sensor system can be combined with the motor in a particularly advantageous manner. A fully automatic method and setting of the axial position of the detector arrangement or of the detector segments can thus be made possible. The sensor system can comprise, for example, one or more distance sensors. At least one distance sensor can be fastened, for example, to at least one detector segment and / or to the basic structure of the gantry. The at least one distance sensor can be configured to determine a distance between the detector segment and the basic structure of the gantry. The sensor system used can be the measurement sensor system of the computed tomography system itself. For example, the computed tomography system can be configured to detect a deviation from the positioning of the detector arrangement classified as ideal on the basis of measurement data, in particular on the basis of CT image data and / or X-ray image data.If the detector arrangement is not in the focus of the X-ray source, i.e. is offset in particular in the axial direction, this generally leads to a deterioration in the image quality. The computed tomography system can be configured to infer, on the basis of the image quality of a computed tomography measurement or an X-ray measurement, whether there is a deviation from the positioning of the detector arrangement classified as ideal. Advantageously, position determination can be possible with the measurement on the basis of CT data without requiring additional sensors. For example, it can be provided to determine the CT data within the scope of a test measurement. Optionally, the computed tomography system can be configured to check a deviation of the position of the detector arrangement or of the detector segments on the basis of the CT data obtained during regular operation. The check can also be transferred to an external monitoring unit.According to one embodiment, the annular x-ray source arrangement has a larger diameter than the annular detector arrangement, such that the x-ray source arrangement is arranged around the examination region further outwards than the detector arrangement, as seen in the radial direction. The diameter can be defined according to the respective ring shape of the detector arrangement or of the X-ray source arrangement. Advantageously, the X-ray source arrangement and the detector arrangement can thereby be constructed in a particularly space-efficient manner. Preferably, the detector arrangement is arranged offset from the X-ray source arrangement in the axial direction such that beam exit openings of the X-ray sources, viewed in the radial direction towards the examination region, are at least partially not, i.e. in particular not completely, covered by the detector arrangement. In particular, it can be provided that a center of the beam exit opening is not covered by the detector arrangement. In some cases, for example for the purpose of collimation, it may be advantageous to limit the beam emission partially, in particular at the edge of the beam, of the detector arrangement or parts on the detector arrangement in a targeted manner.The detector arrangement can preferably be arranged offset in the axial direction with respect to the X-ray source arrangement. With such a configuration, a particularly small offset of detector arrangement to the X-ray sources in the radial direction may be possible, whereby the image quality (compared to a greater offset) may be improved.According to one embodiment, the detector arrangement and the X-ray source arrangement partially overlap in the axial direction. This variant enables a particularly compact design of the gantry. Furthermore, the detector arrangement and the X-ray source arrangement can thereby be assembled particularly closely in the axial direction, whereby an improved image quality can be achieved. In particular, a distance from a focal point of the X-ray sources of the X-ray source arrangement and the detector center can thus be reduced. As a result, for example, less pronounced image errors caused by an offset in the axial direction can occur, or image correction can be correspondingly facilitated.According to one embodiment, the computed tomography system comprises a component container separate from the detector arrangement and the X-ray source arrangement, wherein at least some components of the control electronics of the detector arrangement and / or of the X-ray source arrangement are accommodated in the component container. The control electronics can comprise electronic circuits for controlling the X-ray sources and / or for reading out the detector elements. Additionally or alternatively, further components can be provided in the component container. Further components may be, for example, one or more of: computers, cooling units, control components and others. The component container can allow easier access to the corresponding components. The component container may allow greater flexibility in locating the CT system in a room. The component container can allow a narrower gantry. Optionally, the component container can be fastened or can be fastened to the basic structure. A fastening to the basic structure can be advantageous, for example, for a mobile use. Alternatively, the component container can be provided separately from the gantry. For example, the component container can be connected to the gantry or to components of the gantry by connecting cables.According to the invention, the computed tomography system comprises at least one, in particular removable, guide rail which extends substantially in the axial direction and with which an offset of the detector arrangement, in particular of individual detector segments of the detector arrangement, can be guided in the axial direction. For example, the detector segments or the detector arrangement can be plugged and / or plug-on onto the guide rails. Optionally, the detector segments or the detector arrangement can each comprise one or more feedthroughs through which the guide rails are guided and / or can be guided. Optionally, the detector segments or the detector arrangement can be supported and / or placed on the guide rails. The guide rails can facilitate a displacement of the detector segments or of the detector arrangement. For example, the guide rails can allow manual displacement with little effort. The guide rails may be detachably attached or attachable to the base frame. Advantageously, the guide rails can thus be used, for example, for installation or maintenance and then removed in order to prevent interference with the guide rails during normal operation. Alternatively, the guide rails can be provided permanently on the computed tomography system, in particular on the basic structure. Advantageously, a permanent presence of the guide rails can, for example, speed up maintenance or replacement of the detector segments, in that the guide rails do not first have to be attached.According to the invention, the computed tomography system comprises at least one eccentric disk, in particular a removable eccentric disk, for installing the detector arrangement, in particular a detector segment, in cooperation with the at least one guide rail. The eccentric disc can be part of a guide device which is designed to be plugged onto the guide rail and to be guided on the guide rail. The eccentric disc can be configured integrally with the guide device. This can alternatively be fastened to the remaining guide device. The eccentric disk is preferably designed to be fastened directly or indirectly to the detector arrangement, in particular to the detector segment. The eccentric disc comprises a decentral eccentric opening. The eccentric disc may include a rotational engaging portion. For example, the guide device can comprise a polygonal section (e.g. hexagonal section). The rotation engagement portion may be provided to rotate the guide device together with the eccentric disk. By means of the rotation, a position of the detector arrangement, in particular of the detector segment, can be adjusted in a plane perpendicular to the axial direction. For example, the detector arrangement, in particular the detector segment, can be lowered onto a placement surface. The use of an eccentric disk can enable particularly simple assembly and adjustment. Due to the eccentric disk, sufficient play can be available during assembly and precise adjustment can be made relatively easily during adjustment of the position.A further aspect is a use of a guide rail and an eccentric disk for lowering or raising a detector arrangement, in particular a detector segment of a detector arrangement on a basic structure of a gantry. The lowering or raising can be provided in particular during installation of the detector arrangement or of the detector segment. All advantages and features of the computed tomography system can be transferred analogously to the use of a guide rail and an eccentric disk and vice versa.A further aspect is a method for aligning a detector arrangement, in particular a detector segment, during installation on a basic structure of a gantry of a computed tomography system. The method comprises the following steps:attaching the detector arrangement, in particular the detector segment, to an eccentric disk, wherein the eccentric disk is guided on a guide rail which is fastened to the basic structure, wherein the guide rail runs in particular in the axial direction of the basic structure;adjusting an axial position of the detector arrangement, in particular of the detector segment, by moving the detector arrangement, in particular of the detector segment, along the guide rail;adjusting a position in a plane perpendicular to the axial position by rotating the eccentric disk.All advantages and features of the computed tomography system and the use of a guide rail and an eccentric disk can be transferred analogously to the method for setting a vertical position and vice versa. After alignment, the detector arrangement, in particular the detector segment, can be fastened to the basic structure, for example by screwing. Adjusting the axial position may be assisted by spacers and / or by a motor, in particular as described herein. Optionally, the eccentric disc and / or the guide rail can be removed according to the method. It is also conceivable to perform the steps of adjusting the axial position and adjusting in the plane without performing the other step.A further aspect is a method for aligning a detector arrangement in or on a basic framework of a gantry of a computed tomography system, wherein the detector arrangement comprises in particular at least two detector segments, wherein the method comprises the following steps: (a) determining measured values which indicate a current positioning of the detector arrangement, in particular of the detector segments; (b) determining whether a deviation is present in the axial direction, according to which the current positioning of the detector arrangement, in particular of the detector segments, deviates from an ideal positioning; (c) adapting the positioning in the axial direction of the detector arrangement, in particular of the detector segments, for which a deviation has been determined.All advantages and features of the computed tomography system, the use of a guide rail and an eccentric disk and the method for setting a vertical position can be transferred analogously to the method for aligning a detector arrangement and vice versa.The measured values can be determined with a sensor system. For example, the measured values can be determined using at least one distance sensor. According to one embodiment, distance sensors are used on the basic structure and the detector arrangement or the detector segments in order to obtain measured values in the form of distance measurement data, wherein the positioning is determined on the basis of the distance measurement data. This can represent a simple possibility for directly determining a positioning.According to one embodiment, spacers between the basic framework and the detector arrangement, in particular the detector segments, are used to compensate for deviations in a positioning, in particular the position of the detector segments. The spacers may be spacers as described herein. Deviations can be compensated for, for example, by selecting from a set of different spacers. Optionally, the spacers can be used to compensate for a relative positioning and / or orientation of the detector segments with respect to one another. Optionally, the spacers and a screwing together of at least one detector segment, in particular a base plate of the at least one detector segment, can result in a bracing of the detector segment, in particular of the base plate. A bracing can be effected in order to compensate for unevenness of the detector segment, in particular of the base plate. This may be advantageous, for example, in the case of heat-induced distortions. The base plate may be a base plate as described herein.According to one embodiment, the spacers are fixed by at least one fastening means, in particular one or more screws. The spacers can be fixed independently of the fixing of the detector segments or of the detector arrangement. Alternatively, the spacers can each be fixed together with the respective detector segment or the detector arrangement by at least one common fastening means.According to one embodiment, for adjusting the positioning, the detector arrangement, in particular the detector segments, are offset in the axial direction by a motor.According to one embodiment, for adapting the positioning, the detector segments or the detector arrangement are / is moved in the axial direction on in each case at least one guide rail. Optionally, the at least one guide rail can be attached to the basic frame of the gantry before the adaptation. The at least one guide rail can be removed again after the adaptation. Alternatively, the guide rail can be permanently attached to the basic structure. The movement of the detector segments can be provided manually by a user. Alternatively, the movement of the detector segments can be provided automatically, in particular by a motor. Before the adaptation of the positioning, at least one fastening means of the detector segments which are adapted can be released. The fastening means can be re-fastened after the adjustment of the positioning.According to one embodiment, the deviation is determined by carrying out an x-ray image, in particular a computed tomography image, in order to obtain measured values in the form of at least one x-ray image, and by determining whether image errors occur in the at least one x-ray image, which can be attributed to a positioning of the detector arrangement, in particular of the detector segments. The measured values can indicate a current positioning in that a deviation from a focus position of the detector segments can lead to a deterioration of the image quality. A deviation of the positioning in the axial direction of the detector segments can be determined on the basis of properties of the measured values, for example a reduced image quality. Advantageously, it is thus possible to determine the deviation without the use of an additional sensor system. It can be further advantageous that the effects of the positioning on the measured values are taken into account directly. Thus, this variant is not dependent on a position estimated to be ideal being actually ideal, but rather an optimized or improved position can be found directly on the basis of the image quality within the scope of the applied accuracy.The adjustment of the positioning can be performed manually by a user. The user can be requested by the computed tomography system by a notification to make an adjustment of the positioning. Alternatively, the adjustment of the positioning can be automatically initiated by the computed tomography system. Automatic adaptation can be effected, for example, by means of a motor, in particular as described herein.A further aspect is an annular detector arrangement for a computed tomography system, in particular a detector arrangement as described herein. The detector arrangement comprises at least one, in particular ring-shaped or part-ring-shaped, base plate and one or more module units with detector elements. The base plate is configured such that at least one of the modular units can be attached at least partially in or on the base plate. The detector arrangement can be, in particular, a detector arrangement as described herein. All advantages and features of the computed tomography system, the use of a guide rail and an eccentric disk, the method for setting a vertical position and the method for aligning a detector arrangement can be transferred analogously to the annular detector arrangement and vice versa.According to one embodiment, the detector arrangement comprises at least two separate or separable detector segments each having a base plate and one or more modular units. The base plates may collectively define the ring shape of the detector array.According to one embodiment, the detector arrangement comprises a first aperture part which is fastened to the detector arrangement or is an integral part of the detector arrangement, wherein the first aperture part is configured to provide, together with a second aperture part, an aperture for an annular X-ray source arrangement which has a larger diameter than the detector arrangement. In particular, the aperture can be provided for an X-ray source arrangement as described herein. The first aperture part can be fastened to the housing section, for example.According to a further aspect, a method for adjusting an aperture opening of a computed tomography system with a static gantry, in particular of a computed tomography system as described herein, is provided, wherein the gantry comprises an annular detector arrangement and an annular x-ray source arrangement with a beam exit opening and an annular aperture with at least a first aperture part and a second aperture part, wherein the aperture is arranged in front of the beam exit opening of the x-ray source arrangement, wherein the first aperture part is fastened to the detector arrangement or is an integral part of the detector arrangement, wherein the method comprises the following step:displacing the detector arrangement and thus the first aperture part in the axial direction, so that a distance of the first aperture part from the second aperture part is changed and the aperture opening of the aperture is adjusted.All advantages and features of the computed tomography system, the use of a guide rail and an eccentric disk, the method for setting a vertical position, the method for aligning a detector arrangement and the annular detector arrangement can be transferred analogously to the method for setting an aperture opening and vice versa.According to a further aspect, a method for installing a detector segment on a basic frame of a gantry of a computed tomography system is provided. In the method, a detector segment is raised, in particular with the aid of a support device. Furthermore, the detector segment is brought up to the basic structure. The approach can be guided by at least one guide rail fastened to the basic structure. The approach can be supported by at least one guide aid. In a further step, the detector segment is aligned on the basic structure. All advantages and features of the other aspects can be transferred analogously to this aspect and vice versa. The guide aid can comprise at least one mounting ring, for example. The detector segment can have fastening means, for example screw holes and / or through holes, for fastening the at least one mounting ring. The mounting ring may also have fasteners, such as bolt holes and / or through holes, for attachment to the detector segment. The mounting ring can be configured to guide the guide rail through it. The support device can be configured to be fastened to the detector segment. The support device may comprise at least one support opening for fastening a support means, for example a cable or a chain. The alignment may be provided as described herein. For example, the alignment can be provided with the aid of a motor, an eccentric disk and / or with the aid of spacers.All embodiments described herein may be combined with each other unless expressly stated otherwise.Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 1 shows a schematic sectional view from the side of a static gantry according to an embodiment of the invention, FIG. 2 is a front view of a static gantry viewed in the axial direction according to the embodiment of the invention shown in FIG. 1 , FIG. 3 shows a front view of a gantry according to an embodiment of the invention, FIG. 4 shows an exploded view of a gantry of a computed tomography system according to an embodiment of the invention, FIG. 5 shows a basic structure of a gantry of a computed tomography system according to an embodiment of the invention, in which two of three detector segments are installed, FIG. 6 is an exploded view of a detector segment according to an embodiment of the invention, FIG. 7 shows an exploded view of a gantry of a computed tomography system on the detector side according to an embodiment of the invention, FIG. 8 shows mounting rings and a support device attached to a detector segment by means of screws according to an embodiment of the invention, FIG. 9 shows how a detector segment with support device is slid onto guide rails in order to be attached to a basic frame of a gantry according to an embodiment of the invention, FIG. 10 shows a detector segment on guide rails for installation on a basic frame of a gantry according to an embodiment of the invention, FIG. 11 shows a guide rail detector segment that is slid onto a base frame of a guide rail gantry according to an embodiment of the invention, FIG. 12 shows a detailed view of the seat of a detector segment on a guide rail according to an embodiment of the invention, FIG. 13 is a sectional view of the configuration of FIG. 12 and illustrating use of an eccentric disk to adjust a position of a detector segment according to an embodiment of the invention, FIG. 14 shows a computed tomography system according to an embodiment of the invention, FIG. 15 shows a detailed view of a section of a gantry according to an embodiment of the invention, FIG. 16 shows a diaphragm according to an embodiment of the invention, and FIG. 17 shows a flow diagram of a method for aligning detector segments of a detector arrangement in or on a basic frame of a gantry of a computed tomography system according to one embodiment of the invention.FIG. 1 shows a schematic sectional view from the side of a static gantry 3 according to an embodiment of the invention. FIG. 2 shows a corresponding static gantry 3 in a front view as viewed in the axial direction, according to the same embodiment. The gantry 3 is arranged as a short annular tunnel around an examination region 2. The gantry 3 comprises an annular detector arrangement 6 and an annular x-ray source arrangement 5, which each enclose the examination region 2. The detector arrangement 6 and the X-ray source arrangement 5 have a common axial direction which corresponds to the z-direction drawn in. The detector arrangement 6 is from the right side, as viewed in FIG. 1, and the X-ray source arrangement 5 is attached from the left side to a basic frame 4 of the gantry 3 (not shown here). This means that the detector arrangement 6 and the X-ray source arrangement 5 are attached to the basic framework 4 from different sides. The detector arrangement 6 and the X-ray source arrangement 5 partially overlap in the axial direction, i.e. a part of the X-ray source arrangement 5 is arranged at the same z position as a part of the detector arrangement 6. The X-ray source arrangement 5 has a larger diameter than the detector arrangement 6, so that the X-ray source arrangement 5 is arranged further outwards around the examination region 2 than the detector arrangement 6, as seen in the radial direction, i.e. in the x,y direction. In addition, the detector arrangement 6 is arranged offset from the X-ray source ring 8 in the axial direction such that a beam exit opening of the X-ray source arrangement 5, from which the X-ray fan 50 protrudes, is not completely covered by the detector arrangement 6, as seen in the radial direction towards the examination region 2. A first aperture part 81 is fastened to the detector arrangement 6, which is part of an annular aperture 8 arranged in front of the beam exit opening. A second aperture part 82 of the aperture 8 is arranged opposite the first aperture part 81 as viewed in the axial direction. In this embodiment and preferably also in other embodiments, the first panel part 81 and the second panel part 82 are in particular independent assemblies which, however, interact functionally. The detector arrangement 6 is designed such that it can be displaced together with the first diaphragm part 81 in the axial direction, so that an aperture opening of the diaphragm 8 can be adjusted by displacing the detector arrangement 6 in the axial direction.FIG. 3 shows a front view of a gantry 3 according to an embodiment of the invention. In this view, the detector arrangement 6 can be seen in front of the basic frame 4 of the gantry 3. The detector arrangement 6 comprises three separable detector segments 61, which are each concealed here behind a terminating plate 63. Spacers 11 are used here to adjust an axial position of the detector segments 61. With contact surfaces 41 and contact pins 46, an alignment of the detector segments 61 in the x,y plane is defined. An examination region 2 is provided centrally in the gantry 3, in which examination region a patient can be placed, for example. A foot region 42 provided in the lower region of the basic framework 4 enables a secure standing of the gantry 3 in this and in other embodiments. In operation, the detector ring 6 can be covered towards the outside, for example by a cover 14 (not shown here).FIG. 4 shows an exploded view of a gantry 3 of a computed tomography system according to an embodiment of the invention. A basic frame 4 is a central component of the gantry 3; an X-ray source arrangement 5 and a detector arrangement 6 are attached to the basic frame 4 from opposite sides of the gantry 3. An axial position of the detector arrangement 6 and of the X-ray source arrangement 5 can be adjusted by spacers 11. The spacers 11 can preferably be manufactured from a metal-containing material, in particular steel. For example, the spacers 11 can be metal sheets which can be fixed to the fastening means 12 with screws. In this embodiment, most of the spacers 11 are elongated shims, the longitudinal extent of which runs substantially in the radial direction (i.e. x,y direction). A set of spacers 11 of different thickness may be provided, which can be exchanged as required. A gradation in thickness may be, for example, 0.1 mm. Both the detector arrangement 6 and the X-ray source arrangement 5 each consist of three separable segments. With the aid of this segmentation, assembly and maintenance can be facilitated. On the one hand, the individual segments are less heavy than a complete X-ray source arrangement 5 or detector arrangement 6, and on the other hand, a positioning can be better adjusted with the aid of the segments, in that, for example, irregularities within the X-ray source arrangement 5 or the detector arrangement 6 can also be compensated. Furthermore, a diaphragm 8 is provided here, which is fastened from the side of the X-ray source arrangement 5 to the basic structure 4 by means of holders 85. Spacers 11 can optionally also be provided for fastening the panel 8. The spacers 11 of the panel 8 can be positioned, for example, between the holders 85 and the basic structure 4.FIG. 5 shows a basic structure 4 of a gantry 3 of a computed tomography system according to an embodiment of the invention, in which two of three detector segments 61 are installed. The detector segments 61 are essentially ring segments, each of which forms a partial ring of the annular detector arrangement 6. Each of the detector segments 61 comprises a base plate 62 and a housing section 64 for each base plate 62, Module units 65 with detector elements can be inserted into the housing section 64. With the spacers 11, an alignment of the detector segments 61 can be set precisely. The gantry 3 comprises fastening means, for example screw holes and slots, for fixing the spacers 11. Furthermore, a positioning in the x,y plane can be defined by contact surfaces 41 and contact pins 46.FIG. 6 shows an exploded view of a detector segment 61 according to an embodiment of the invention. The detector segment 61 comprises a base plate 62 and a housing section 64 Two module units 65 with detector elements (here the two module units 65 are already linked to one another) can be inserted in the housing section 64. In order to make insertion of the module units 65 simple, in particular without having to remove the base plate 62, the base plate 62 has a corresponding opening. Closing plates 63 can be placed on this opening. Spacers 66 are provided between the end plates 63 and the module units 65. Both the spacers 66 and the end plates 63 have holes through which connection from the module units 65 to a readout electronics 68 can be made possible.Space can thus advantageously be saved in the region of the detector elements themselves and the detector elements can be placed closer to the X-ray sources.FIG. 7 shows an exploded view of a gantry 3 of a computed tomography system on the detector side according to a further embodiment of the invention. The X-ray source arrangement 5 is not shown in this illustration. The detector arrangement 6 is fastened to the basic structure 4, wherein an axial position can be adjusted with spacer 11. Electronics covers 69 serve to protect the read-out electronics 68 of the detector elements.In addition, a cover 14 is provided to protect the detector arrangement 6. A (here ring-shaped) luminous marking unit 17 serves to mark an area on a subject to be examined (e.g. a patient) or object with a light marking, e.g. a cross.FIGS. 8 to 11 show the installation of a detector segment 61 on a basic frame 4 of a gantry 3 according to an embodiment of the invention. Figure 8 shows how mounting rings 43 and a support device 44 are attached to the detector segment 61 by means of screws. With the support device 44, the detector segment 61 can be easily lifted, for example with a cable. In Fig. 9 it is shown how the detector segment 61 is slid on guide rails 10 to be attached to a basic frame 4. Detector segment 61 and backbone 4 may correspond to those shown in Figures 3 and / or 5. In FIG. 10 it is shown how the support device 44 has now been removed and the detector segment 61 now rests on the guide rails 10. By attaching spacers 11, an intended axial position of the detector segment 61 can be adjusted. In FIG. 11, the detector segment 61 is now pushed onto the basic frame 4 on the guide rails 10. Optionally, the displacement may be provided by at least one motor configured to adjust the positioning of the detector segment 61 in the axial direction. The motor 15 can be a spindle drive, for example. Optionally, the guide rail 10 may be a threaded rod used for movement caused by the motor. Spacers 11 define the axial position of detector segment 61. in the motored version, spacers 11 may optionally be omitted, and the positioning of detector segment 61 may be adjusted solely via the motor. In principle, the detector segment 61 can now be fastened to the basic frame 4, e.g. with screws, and the guide rails 10 can be removed. Optionally, an adjustment of the position can also be carried out as indicated in FIGS. 12 and 13. FIG. 12 shows a detailed view of the seat of the detector segment 61 on the guide rail 10; FIG. 13 shows a sectional view of the same from FIG. 12, so that an eccentric disk 45 which is seated on the guide rail 10 is visible. As shown in FIG. 13, by rotating the eccentric disc 45, a lowering of the detector element can be effected, which thus comes to rest against a contact surface 41. Due to the eccentric disk 45, the detector segment 61 initially has sufficient play to be able to be displaced on the guide rail 10. By rotating the eccentric disk 45, the detector segment 61 can subsequently be brought precisely into the intended x,y position.Fig. 14 shows a computed tomography system according to an embodiment of the invention. A gantry 3, a patient couch 18 and a component container 19 can be seen here. the gantry 3 can be configured analogously as described in one of the other figures. In this embodiment, the component container 19 is separate from the detector arrangement 6 and the X-ray source arrangement 5. At least some components of the control electronics of the detector arrangement 6 and / or of the X-ray source arrangement 5 are accommodated in the component container 19. The control electronics can comprise, for example, electronic circuits for controlling the X-ray sources or for reading out the detector elements. Optionally, further components can be provided in the component container 19. The component container 19 is connected to the gantry 3 or to components of the gantry 3 by connecting cables. The component container 19 can allow easier access to the corresponding components, e.g. for the purpose of maintenance. Optionally, the component container 19 can be fastened or can be fastened to the basic structure 4.FIG. 15 shows a detailed view of a section of a gantry 3 according to an embodiment of the invention. An area around the origin of an X-ray fan 50 can be seen. The X-ray fan 50 starts from an X-ray source and is bounded by a diaphragm 8. A first aperture part 81 together with a second aperture part 82 forms a deep shaft aperture. The first aperture part 81 is formed by a part of the detector arrangement 6. Optionally, the diaphragm 8 can also be formed as shown in FIG. 16. In this case, the diaphragm 8 also consists of a stabilizing plate 88 made of a first material and of segments 87 made of a second material.In Fig. 16 there is shown a shutter 8 according to an embodiment of the invention. Specifically, the diaphragm 8 shown comprises the second diaphragm part 82 according to the invention. the diaphragm 8 comprises a shielding base plate 86 made of a first material which shields X-rays, and segments 87 made of a second material which shields X-rays and which are arranged on the shielding base plate 86, the second material having stronger X-ray shielding properties than the first material. The first and second materials are joined by welding, for example. The segments 87 are arranged circumferentially in the circumferential direction of the diaphragm 8. Furthermore, stabilizing plates are provided. The stabilizing plates have a radial main extension (in the x, y direction) and run perpendicular to the segments 87 of the second material. The segments 87 are preferably made at least partially of tungsten. The first X-ray shielding material can be, for example, lead, brass or copper.FIG. 17 shows a flow diagram of a method for aligning detector segments 61 of a detector arrangement 6 in or on a basic frame 4 of a gantry 3 of a computed tomography system according to one embodiment of the invention. In a first step 101, measured values are determined which indicate a current positioning of the detector segments 61. For this purpose, an x-ray image can be carried out, for example, in order to obtain measured values in the form of at least one x-ray image. Alternatively or additionally, distance sensors can be used on the basic structure 4 and the detector segments 61 in order to obtain measured values in the form of distance measurement data. In a further step 102, it is determined whether there is a deviation in the axial direction, according to which the current positioning of the detector segments 61 deviates from an ideal positioning. The deviation can be determined, for example, by determining whether image errors occur in a recorded x-ray image, which can be attributed to a positioning of the detector segments 61. Alternatively or additionally, the positioning can be established on the basis of distance measurement data. In a further step 103, the positioning in the axial direction of the detector segments 61 for which a deviation has been determined is adapted. For this purpose, spacers 11 can be used, for example, between the basic structure 4 and the detector segments 61 in order to compensate for the deviations in the positioning. Optionally, to adjust the positioning, the detector segments 61 can be axially displaced with a motor.

Claims

Computed tomography system comprising an examination region (2) and a gantry (3), wherein the gantry (3) comprises a basic framework (4), an annular detector arrangement (6) with detector elements and an annular X-ray source arrangement (5) with X-ray sources, wherein the detector arrangement (6) and the X-ray source arrangement (5) each at least partially surround the examination region (2) and have substantially a common axial direction, wherein the detector arrangement (6) and the X-ray source arrangement (5) are attached or can be attached to the basic framework (4) from different sides as seen in the axial direction, wherein the computed tomography system comprises at least one guide rail (10), which runs substantially in the axial direction and with which an offset of the detector arrangement (6), in particular individual detector segments (61) of the detector arrangement (6), can be guided in the axial direction, wherein the computed tomography system comprises at least one eccentric disk (45) for installing the detector arrangement (6) in cooperation with the at least one guide rail (10).Computed tomography system according to claim 1, wherein the detector arrangement (6) comprises at least two separate or separable detector segments (61) each having at least one detector element.Computed tomography system according to claim 2, wherein the computed tomography system is configured such that a positioning of the individual detector segments (61) in the axial direction of the detector arrangement (6) is adjustable.Computed tomography system according to claim 2 or 3, wherein replaceable spacers (11) are provided between the detector segments (61) and the base frame (4), so that the positioning of the detector segments (61) in the axial direction of the detector arrangement (6) with the spacers (11) is adjustable.Computed tomography system according to one of the preceding claims, wherein the computed tomography system comprises an annular diaphragm (8) for the X-ray source arrangement (5), wherein the diaphragm (8) comprises a shielding base plate (86) made of a first material shielding X-ray radiation, and segments (87) made of a second X-ray radiation shielding material, in particular made of tungsten, arranged on the shielding base plate (86), wherein the second material has stronger X-ray shielding properties than the first material.Computed tomography system according to claim 5, wherein the aperture (8) comprises at least a first aperture part (81) and a second aperture part (82), wherein the first aperture part (81) is fastened to the detector arrangement (6) or is an integral part of the detector arrangement (6).Computed tomography system according to one of the preceding claims, wherein the computed tomography system comprises a component container (19) separate from the detector arrangement (6) and the X-ray source arrangement (5), wherein at least some components of the control electronics of the detector arrangement (6) and / or of the X-ray source arrangement (5) are accommodated in the component container (19).Computed tomography system according to one of the preceding claims, wherein the at least one guide rail (10) is removable.Computed tomography system according to one of the preceding claims, wherein the at least one eccentric disc (45) is removable.

Images