X-ray collimator and X-ray imaging facility

Abstract

The utility model relates to an X-ray collimator (RK) and an X-ray imaging facility. The utility model relates to an X-ray collimator (RK) for automatically displaying an X-ray field (RS) emitted by an X-ray source (RQ) of an X-ray imaging installation (RB), comprising:-a first aperture unit (BE1); and-a second aperture unit (BE2), the first aperture unit (BE1) being designed to display the X-ray field (RS) symmetrically with respect to a central beam (ZS) of the X-ray field (RS), and the second aperture unit (BE2) being designed to further delimit the symmetrically displayed beam field asymmetrically with respect to the central beam (ZS).

Description

Technical Field

[0001] The utility model relates to an X-ray collimator, in particular for a medical X-ray imaging facility. The X-ray collimator is provided with a plurality of blades for automatically gradually displaying a ray field. Background Art

[0002] In medical X-ray imaging, typically in classical radiography, an X-ray source generates X-ray radiation. The X-ray radiation penetrates the body region to be examined, such as the subject being examined, a human or animal patient, and is absorbed or scattered to varying degrees by different tissue types. The attenuated X-ray radiation is detected in a spatially resolved manner by an X-ray detector arranged opposite the X-ray source. The detector data generates the digital X-ray image record, which is typical today.

[0003] In order to keep the X-ray dose as low as possible during X-ray examinations of patients, the generated X-rays that impact the body area to be examined are collimated. That is, after exiting the X-ray source, the X-rays are shaped or limited by an aperture device. A square or rectangular radiation field, in any case symmetrical about the central beam of the X-ray radiation, is typical. This is particularly applicable to radiography, fluoroscopy, and / or urology (RFU for short). However, other field shapes are also possible and may be necessary for specific examinations. The aperture is made of a material that absorbs X-ray radiation, such as lead or tungsten.

[0004] Symmetrical fade-in typically requires that, for fading in the X-ray image, the collimator blades are coupled at least in pairs and moved symmetrically with respect to the central ray. Therefore, asymmetrical fade-in is generally not easily possible.

[0005] Specifically, a collimator in the RFU field usually includes two blade planes.

[0006] The main blade plane has the greatest possible distance from the X-ray focal point, which is close to the radiation exit window of the X-ray source. This large distance results in the greatest possible precision with respect to the dimensions of the radiation window to be set, the best possible edge quality with respect to the radiation window or the set image field, and thus also improved reproducibility of the generated X-ray images and the blade positions.

[0007] In contrast, the blade plane near the focus is positioned as close as possible to the focus / radiation exit window. The blades of this plane typically move synchronously with the main blades and are not imaged. They are more like a ray exit window of variable size and, especially with small ray fields or image formats, reduce out-of-focus and scattered radiation.

[0008] Therefore, for asymmetric fade-in, the patient must be frequently repositioned. Imaging systems typically do not provide corresponding motorized axes of motion, such as a movable table, requiring the operator of the imaging system to manually reposition the patient. This hinders the increasing automation and efficiency of the imaging process and requires greater staffing.

[0009] As an alternative to repositioning the patient, a more symmetrical fade-in can be selected with the aid of the collimator leaves. This results in a higher and therefore undesirable radiation exposure for the patient.

[0010] Furthermore, X-ray imaging systems are known which have collimators for asymmetrically fading in, wherein these systems are usually only cumbersome and not very intuitive to operate and are technically complex in design.

[0011] In particular, the mechanical coupling of the main blade plane with the near-focus blade plane requires significantly more installation space in asymmetrically collimated systems and is a challenge, since typically four main blades in such systems are driven individually and are correspondingly individually coupled to the respective near-focus blades.

[0012] In addition to the actual main fade-in, various auxiliary mechanisms are also used in the RFU field to improve the image quality, in particular wedge filters, additional blades or contour filters.

[0013] Wedge filters are typically used in fluorescence photography. Three different wedge filters are actually used there, each with its own drive and positioning mechanism. A disadvantage is that for most applications, only one wedge filter is required, and largely two-thirds of the mechanism and drive remain unused.

[0014] Contour filters are primarily used in radiography and must be manually mounted on the collimator as an accessory using operating forces, which in turn hinders automation of the recording process.

[0015] In summary, the auxiliary mechanisms are each very specific for a relatively small selection of applications and, however, have previously required their own additional operating mechanism or manual operation. The result is that the correspondingly limited areas of use are filled with individual auxiliary mechanisms with complex operation and / or complicated construction. Utility Model Content

[0016] Based on this, the object is to provide a mechanism for asymmetric fade-in, wherein the asymmetric fade-in can be operated simply, in particular automatically. Another object of the present invention is to provide a mechanism that allows symmetrical fade-in with a simple design and a small installation space requirement. Another object is to reduce the component complexity of various auxiliary mechanisms for fade-in and to facilitate their operation.

[0017] The object is achieved by an X-ray collimator and an X-ray imaging device according to the invention for automatically fading an X-ray field. Preferred and / or alternative advantageous design variants are the subject matter of the following text.

[0018] The first aspect of the present invention relates to an X-ray collimator for automatically fading an X-ray field emitted by an X-ray source of an X-ray imaging device, which is also referred to as a collimator in the specification for simplicity. The X-ray collimator comprises:

[0019] - a first aperture unit, and

[0020] -Second aperture unit.

[0021] The first aperture unit is designed to fade in the x-ray field symmetrically with respect to a central ray of the x-ray field. The second aperture unit is designed to further limit the symmetrically faded ray field asymmetrically with respect to the central ray.

[0022] The first aperture unit and the second aperture unit are used to set or determine the size and / or shape of the X-ray field (hereinafter referred to as the ray field). Therefore, the first aperture unit and the second aperture unit respectively play an imaging role.

[0023] In a preferred embodiment of the present invention, the first aperture unit and the second aperture unit are fixedly integrated into the collimator or arranged in a collimator housing that defines an outer edge of the collimator.

[0024] Furthermore, in a preferred embodiment of the collimator, a third aperture unit may be included. The third aperture unit is primarily used to reduce out-of-focus radiation or scattered radiation. It does not directly play an imaging role, but helps to improve the quality of the generated X-ray image.

[0025] The inventors have recognized that, from the user's perspective, significant advantages can be achieved by providing, in addition to the first aperture unit for classic symmetrical fade-in, also a unit for asymmetrical fade-in directly in the collimator. Furthermore, the inventors have recognized that automating the operation of both the first and second aperture units also offers operational advantages.

[0026] The second aperture unit is preferably arranged downstream of the first aperture unit in the direction of beam propagation. This means that the beam field emitted by an associated X-ray source, such as an X-ray tube, first passes through the first aperture unit and then through the second aperture unit. Thus, the beam field is initially shaped symmetrically by the first aperture unit about its central beam. According to the present invention, it is now possible to shape the beam field asymmetrically as it progresses, i.e., downstream of the first aperture unit, as needed, depending on the examination to be performed. This specifically means that the symmetrically evolving beam field is further asymmetrically delimited.

[0027] In a particularly preferred embodiment of the present invention having a third aperture unit, the third aperture unit is still positioned upstream of the first aperture unit in the direction of radiation propagation. More specifically, the third aperture unit is positioned as close as possible to the radiation focus, for example, directly downstream of the radiation exit window of the X-ray source. This allows undesirable radiation contributions to be removed at the very beginning of the radiation path.

[0028] For symmetrical fading, the first aperture unit comprises at least one blade pair, i.e. at least two related blades. In this case, in an embodiment of the invention, the blades have straight ray edges. A ray edge is understood to be an edge of a blade oriented toward the central ray. In an embodiment, the two blades of at least one blade pair are arranged opposite each other and are configured to move in a coupled manner transversely to the ray propagation direction toward the central ray or away from the central ray. In a preferred embodiment, the ray edges of the two blades are arranged parallel to each other. Thereby, the first aperture unit comprising the blade pair is configured in particular to fade in the ray field in a rectangular manner or to produce a rectangular image field. Due to the symmetrical arrangement of the blade pairs with respect to the central ray, the rectangular ray field is also oriented symmetrically with respect to the central ray. In another advantageous embodiment, the first aperture unit comprises two blade pairs configured as described above, wherein the blade pairs are arranged at an angle of 90° relative to each other around the central ray. The first aperture unit now allows a rectangular and in particular square fading of the ray field or the production of a square image field that is symmetrical with respect to the central ray.

[0029] Alternative designs of the first aperture unit are also conceivable, for example an iris aperture for generating a circular beam field.

[0030] In one embodiment of the collimator, the two blades of at least one blade pair are designed to be coupled, i.e., their movements are coupled. The blades always move synchronously and, in doing so, travel the same, but opposite or mirror-image, adjustment paths. In a preferred embodiment, the adjustment path runs along a straight line. However, in other embodiments, the adjustment path can also be curved and, for example, correspond to a circular or elliptical path.

[0031] In one embodiment of the present invention, both blades of at least one blade pair are identical in both shape and X-ray absorption properties. Particularly preferably, the blades of the first aperture unit have a rectangular basic shape and are 100% X-ray-opaque. This means that they completely or substantially completely absorb incident X-rays. In one embodiment, the blades of the first aperture unit are formed as lead blades. However, other materials with similar absorption properties, such as tungsten, are also conceivable.

[0032] In embodiments of the collimator, the second aperture unit includes at least one additional blade, that is, embodiments with exactly one additional or additional blade, but also embodiments with more than one additional blade. For example, two or three additional blades may be included. In embodiments with two or more blades, the blades are particularly preferably also arranged offset by 90° relative to one another. However, the second aperture unit is not limited to these embodiments. Any angular position of the at least one additional blade is conceivable.

[0033] In one embodiment, at least one additional blade also has a straight ray edge. In one embodiment, the ray edge can be oriented parallel to the ray edges of the blades of the first aperture unit. In another embodiment, the ray edge is oriented at an acute or obtuse angle relative to the ray edges of the blades of the first aperture unit. In this way, the second aperture unit can generate not only ray fields or image fields that are asymmetric about the central ray, but also ray fields or image fields that differ from a quadrilateral shape.

[0034] In other embodiments, the beam edge of at least one additional blade is curved. Advantageously, the curvature is concave in the direction of the central beam, so that a circular shape of the beam field or image field can be approached via the additional blade. Regarding the angular position of the additional blade relative to the blades of the first aperture unit, the above-described conditions apply.

[0035] According to an embodiment variant, the basic shape of at least one further blade can be very different. Here, a rectangular basic shape similar to the blades of the first aperture unit is conceivable, but any other shape, in particular a free-form shape, is also conceivable.

[0036] Correspondingly, in a preferred embodiment, the second aperture unit is designed to adjust at least one further blade parallel to one or all blades of the first aperture unit and transversely to the beam propagation direction.

[0037] To this end, it should be ensured that the movement of the at least one additional blade is not coupled to the movement of the blades of the first aperture unit. In other words, the second aperture unit can be configured to adjust the at least one additional blade independently of the movement of the blades of the first aperture unit. In other words, in one embodiment of the collimator, only the additional blades of the second aperture unit can be used to delimit the beam field, while the blades of the first aperture unit remain in their respective rest positions, in which they do not contribute to beam shaping. The rest positions are defined in this context such that they are outside the maximum beam field or do not contribute to beam shaping. The maximum beam field corresponds to the propagation of the X-ray radiation as would occur without any fading. In contrast, in other embodiments, beam shaping is achieved solely by the blades of the first aperture unit, with the additional blades of the second aperture unit not contributing to beam shaping. In these embodiments, the additional blades are in their rest positions outside the maximum beam field.

[0038] In this way, the collimator according to the present invention can be matched to multiple different fade-in situations corresponding to multiple different imaging processes simply by adjusting multiple blades of the first aperture unit and / or the second aperture unit.

[0039] As explained at the outset, the angular position of the additional blades relative to the blades of the first aperture unit can be different. However, the second aperture unit is particularly preferably designed to change the angular position of at least one additional blade relative to at least one blade pair of the first aperture unit. In other words, the second aperture unit includes a mechanism by which the angular position of the additional blades can be adjusted or set. This allows the same collimator to be adapted to different inspection requirements.

[0040] To advantageously enable automatic positioning of the at least one further blade, the second aperture unit includes a drive module comprising at least one drive device for the adjustment movement of the at least one further blade. In one embodiment, each of the at least one further blade may include its own drive device. In another embodiment, two further blades may be coupled to the drive device. In particular, the corresponding drive train configuration ensures that the further blades nonetheless follow different adjustment paths. In another embodiment, more than one drive device may also be provided for the further blade, for example if the further blade has more than one degree of freedom.

[0041] In one embodiment, the drive device can be designed as an electric drive device, in particular an electric motor. The drive module is advantageously positioned within the second aperture unit in the collimator housing, so that the kinematic transmission path is advantageously shortened.

[0042] In addition, it should be noted that the first aperture unit also has a similarly designed drive module, which includes at least one drive device designed as described above. Particularly preferably, the drive module of the first aperture unit includes a drive device for each blade pair, so that the movement of the blades of the blade pair is forced to be coupled via a common drive device.

[0043] The drive module of the first aperture unit and the second aperture unit advantageously enables fully automatic fading-in both for symmetrical and for asymmetrical image fields.

[0044] In order to achieve a precise and reproducible adjustment movement for the at least one further blade, the second aperture unit comprises in an embodiment of the collimator at least one guide device for the at least one further blade, which is designed to allow a translation and / or rotation of the at least one further blade.

[0045] In an embodiment of the adjustment path for translation, the guide device can comprise a straight guide rail, a guide web or a guide rod, along which the at least one further blade is moved driveably by the drive module.

[0046] In another embodiment of a rotational adjustment path, the guide device can include at least one aperture disk rotatably mounted about a central beam, with at least one additional blade attached to the aperture disk. For the rotational adjustment movement, in particular for changing the angular position of the additional blade relative to the first aperture unit, the disk is driven in rotation by means of a drive module.

[0047] However, other configurations of the guide device are also conceivable, for example a rotation axis, about which the at least one further blade can be rotated in a guided manner.

[0048] In order to improve the adaptability of the collimator to different examination scenarios as well as possible, it is proposed in other embodiments of the present invention that at least one additional blade is configured as an X-ray-impermeable or at least partially X-ray-transparent blade. In other words, at least one additional blade can be configured as a completely or substantially completely absorbing blade, for example a blade composed of lead or tungsten. Alternatively or additionally, at least one additional blade can be configured as a partially X-ray transparent blade, for example in the form of a thin steel blade. In a particularly preferred embodiment, the partially X-ray transparent blade is configured in the form of a wedge-shaped blade whose thickness increases continuously over the blade width. Preferably, the thickness of the wedge-shaped blade is smallest in the area oriented toward the central ray and increases as the distance from the central ray increases. The thicker the material of the additional blade, the stronger the X-ray absorption.

[0049] As already mentioned, at least one further blade can alternatively or additionally be designed as a contour filter. Contour filters are particularly characterized by their curved beam edges, which contribute to the free-form shaping of the beam field or field of view. In a preferred embodiment, the shape or curvature of the beam edge is adapted to the patient's specific anatomy, such as the shoulder joint.

[0050] In order to avoid unnecessarily increasing the overall height of the collimator in the direction of beam propagation by the second aperture unit, while still being able to stock a plurality of different additional blades for the second aperture unit for automated phasing, the collimator, in another embodiment, includes at least one magazine for accommodating at least three additional blades. The X-ray collimator includes a replacement device for placing one of the three additional blades in the second aperture unit. In other words, a storage location is provided for the at least three additional blades via the magazine, which is not integrated into the second aperture unit itself but rather external to it. To prepare the collimator for the upcoming imaging, a suitable blade from the three stored additional blades can now be selected and placed in the second aperture unit. Advantageously, the present invention provides a replacement device for automating the assembly of the second aperture unit or magazine for this purpose. The replacement device may, for example, include a slide or a gripper that can be used to grasp and reposition one of the additional blades. In one embodiment, the replacement device may include a robotic unit, such as a robotic arm, to which the gripper or slide is attached. In a preferred embodiment, the replacement device is at least partially integrated into the second aperture unit and / or the collimator housing and / or the magazine in a space-optimized manner.

[0051] In order to enable an automated replacement process, the second aperture unit can include at least one, alternatively multiple, retaining means for one of the at least one further blade, by means of which the correct positioning of the at least one further blade, for example relative to the guide device, can be achieved in a virtually automatic manner. To this end, the at least one retaining means can, for example, be provided with magnetic retaining elements at the guide device and the further blade, which, once brought into sufficient spatial proximity by the replacement device, adhere to one another and hold the further blade in the desired position. Alternatively, the at least one retaining element can include a locking or latching element at the further blade or the guide device, which is also fixedly connected with a contact fit in order to position the further blade in the second aperture unit.

[0052] In one embodiment, it is provided that when replacing or placing a further blade in the second aperture unit, positioning always takes place at a position corresponding to the rest position of the further blade.

[0053] In some embodiments of the collimator, a magazine for additional blades of any design of the second aperture unit is arranged on the collimator housing in the region of the second aperture unit in the direction of radiation propagation, thereby achieving a particularly space-optimized arrangement. This means that the magazine is externally attached to the collimator housing, more precisely, at the level of the second aperture unit. The magazine may extend beyond the height of the second aperture unit in the direction of radiation propagation, but is preferably designed so that it does not increase the overall height of the collimator in the direction of radiation propagation. In other words, the present invention utilizes the recognition that, in addition to the second aperture unit, the magazine can also be arranged in the region of other units integrated into the collimator, such as the first aperture unit and / or the unit for detecting the dose-area product, also known as the DAP chamber.

[0054] The blades of the first aperture unit are typically arranged at a distance of approximately 200 mm from the X-ray focal point, while in a preferred embodiment, the distance between the at least one additional blade in the second aperture unit amounts to a value between 220 mm and 250 mm, preferably between 235 mm and 245 mm, for example, 240 mm or 244 mm. This increases the overall height of the collimator only slightly compared to a design without a second aperture unit. Advantageously, the second aperture unit at least partially utilizes already available but previously unused structural space within the collimator.

[0055] The above dimensions relate to a distance of 1000 mm between the X-ray focus and the image plane or detection surface (also called source-image distance (SID)). Here, the maximum beam field or image field (with all blades of the first and second aperture units in their resting position) has a diameter or width of 450 mm.

[0056] Another aspect of the present invention relates to an X-ray imaging system. The X-ray imaging system is preferably configured as a medical X-ray imaging system for generating medical X-ray image data of a patient's body region to be examined. In this context, the following description will be based on a human patient as the examination subject. In principle, the patient can also be an animal. Alternatively, the examination subject can be a plant or an inanimate object, such as a historical artifact.

[0057] An X-ray imaging system includes an X-ray collimator according to the present invention. The medical X-ray imaging system is preferably designed as a transmission X-ray system. The transmission X-ray system is particularly designed to produce two-dimensional X-ray image recordings. In a preferred embodiment, the medical X-ray imaging system is thus designed as a radiography system, a fluoroscopy system, a urology system, or a mammography system. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The above-mentioned characteristics, features, and advantages of the present invention, as well as the manner and method of achieving the same, will become clearer and easier to understand with reference to the following description of the embodiments, which are described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described in this description. In the different drawings, the same components are provided with the same reference numerals. The drawings are generally not to scale. The drawings show:

[0059] Figure 1 A detailed view showing an X-ray imaging facility including an X-ray collimator in one embodiment of the present invention,

[0060] Figure 2 shows a detail view of an X-ray collimator with two additional leaves in one embodiment of the invention,

[0061] Figure 3 A detailed view showing an X-ray collimator with additional leaves in another embodiment of the present invention,

[0062] Figure 4 A diagram showing an X-ray collimator according to the present invention including a filter storage bin in another embodiment of the present invention,

[0063] Figure 5 A top view of an asymmetrically faded ray field according to the present invention in one embodiment is shown,

[0064] Figure 6 A top view showing an asymmetrically faded ray field according to the invention in an alternative embodiment, and

[0065] Figure 7 A plan view of an asymmetrically faded ray field according to the invention is shown in a further alternative embodiment. DETAILED DESCRIPTION

[0066] Figure 1A detailed view of an X-ray imaging facility RB including an X-ray collimator RK in one embodiment of the present invention is shown. The X-ray imaging facility RB is a medical X-ray imaging facility and is used to detect or record medical X-ray images of a body region of interest of a patient. For this purpose, the X-ray imaging facility RB includes an X-ray source RQ, which generates X-ray radiation in a focal spot or X-ray focus RF and emits an X-ray field RS through an exit window AF of the X-ray source RQ. In this case, the X-ray field RS propagates in a ray propagation direction AR corresponding to its central ray ZS in the center of the X-ray field RS. The X-ray field RS passes through the patient's body tissue and its intensity is thereby attenuated. Downstream of the patient, the X-ray field RS impinges on an X-ray detector (not shown), which detects the attenuated X-ray field RS pixel by pixel in a position-resolved manner. A currently typical digital X-ray image is generated from the detector data.

[0067] The X-ray imaging system RB is designed in particular as a radiography system, a fluoroscopy system or a urology system, all of which are associated with classical projection X-rays or fluoroscopic X-rays.

[0068] In order to keep the X-ray dose for the patient advantageously low and at the same time to avoid losses in image quality, the X-ray imaging system RB also includes an X-ray collimator RK, which is described in detail below.

[0069] The X-ray collimator RK is used to collimate or limit or gradually expand the X-ray field RS starting from the largest, unrestricted radiation field MRS. This allows the image field, i.e., the area of the patient's body shown by means of X-ray imaging, to be optimally limited and minimized. This allows body tissue that is not of interest to be protected.

[0070] The X-ray collimator RK is designed to automatically fade in the X-ray field RS. For this purpose, it comprises a first aperture unit BE1 and a second aperture unit BE2. The first aperture unit BE1 is configured to fade in the X-ray field RS symmetrically with respect to the central ray ZS of the X-ray field RS, while the second aperture unit BE2 is designed to further limit the symmetrically faded-in X-ray field asymmetrically with respect to the central ray ZS. The result is a beam field or image field that is asymmetrical with respect to the central ray ZS. This has a significant advantage, for example: for dose-optimized X-ray image recording, the operator no longer has to manually reposition the patient; instead, the beam field can be asymmetrically adapted to the desired body region at the touch of a button.

[0071] For this purpose, the X-ray collimator RK advantageously comprises a rotation device (not shown) which is designed to rotate the entire collimator relative to the X-ray source RQ or the patient.

[0072] In the illustrated embodiment, the X-ray collimator RK also includes a third aperture unit BE3, which is arranged upstream of the first aperture unit BE1 in the propagation direction AR. This third aperture unit BE3 is positioned directly downstream of the exit window AF of the X-ray source RQ and serves to reduce out-of-focus radiation and scattered radiation. In this embodiment, the third aperture unit BE3 includes four blades pointing toward the exit window and movable relative to the central ray ZS.

[0073] In the propagation direction AR, the second aperture unit BE2 is arranged downstream of the first aperture unit BE1 . Advantageously, the second aperture unit BE2 is arranged largely in the actually free and existing installation space of the collimator housing, so that the overall height of the collimator RK remains approximately unchanged.

[0074] The first aperture unit BE1 currently comprises a first blade pair LP1 and a second blade pair LP2. The blades of the first and second blade pairs LP1 and LP2 are arranged opposite each other. Therefore, during collimation, the blades of the blade pairs LP1 and LP2 move toward or away from each other transversely to the propagation direction AR. To maintain the symmetry of the beam field RS, the blades of the blade pairs LP1 and LP2 are coupled so that they always traverse the same adjustment path in terms of distance. Thus, the central beam ZS is centered between the blades of the blade pairs LP1 and LP2 in all positions, regardless of their position. Each blade has a basic rectangular shape with straight beam edges. All blades of the first aperture unit BE1 are designed as 100% X-ray-opaque lead blades. The blade pairs LP1 and LP2 are oriented at a 90° angle relative to each other. The movement of the blade pairs LP1 and LP2, in contrast, is uncoupled and is each performed by its own drive unit or transmission system. Thus, the first aperture unit BE1 is designed to generate a rectangular or square beam field RS.

[0075] However, a coupling mechanism KM, comprising a plurality of gears or adjustment disks, exists between the first aperture unit BE1 and the third aperture unit BE3, so that an adjustment movement of the blades of the blade pair LP1, LP2 results in a corresponding adjustment movement of the blades of the third aperture unit BE3. This ensures an optimal position for the third aperture unit BE3 for every position of the blade pair LP1, LP2, and automatically removes undesirable radiation contributions from the radiation field RS.

[0076] The X-ray collimator RK advantageously comprises a measuring chamber DK, for example in the form of a DAP chamber, which serves to determine the X-ray dose applied during the X-ray imaging, particularly with regard to the size of the emerging radiation field RS.

[0077] Furthermore, the X-ray collimator RK also comprises a camera device K, which is arranged laterally on the collimator housing and serves to detect the patient position.

[0078] Furthermore, further components may be included, for example a mirror arrangement SA including an X-ray transparent mirror and a light source in the form of a lighting device for generating visible light, whereby the currently emerging X-ray field RS in the image plane can be made visible to the operator.

[0079] Figure 2 A detailed view of the X-ray collimator RK is shown. As already described at the outset, the second aperture unit BE2 comprises at least one further blade WL. Figure 2 The embodiment variant of the second aperture unit BE2 shown in FIG. includes two additional blades WL1 and WL2. The components of the second aperture unit BE2 are arranged on a supporting base plate BP, via which the second aperture unit BE2 can be mounted in the housing of the collimator RK. The two additional blades WL1 and WL2 are rectangular, just like the blades of the first aperture unit, and in particular, have straight beam edges. The two additional blades WL1 and WL2 are oriented at right angles to each other. They are designed to be independently adjustable along a straight line toward or away from the central beam. In particular, the two additional blades WL1 and WL2 are oriented substantially identically to the two blades of the first aperture unit BE1, which are arranged at right angles to each other, i.e., their beam edges are parallel to each other. Thus, at least one additional blade WL1 and WL2 can be adjusted parallel to the blades of the first aperture unit BE1 and transversely to the beam propagation direction AR. In this way, the beam field RS, which is symmetrically bounded by the first aperture unit BE1 or not bounded at all by the first aperture unit BE1, can be (further) bounded on both sides to achieve a rectangular, particularly square, beam field RS, but offset relative to the central beam ZS, i.e., asymmetrical therewith. To adjust the two additional blades WL1, WL2, the second aperture unit includes a guide device FV with two guide rails FS provided for each blade WL1, WL2. The additional blades WL1, WL2 are each suspended in these guide rails and can be moved translationally along these guide rails FS. To this end, the additional blades WL1, WL2 are each driven by a drive device in the form of an electric motor EM via a toothed belt ZR preloaded by spring tension. Together, the two electric motors EM form the drive module AM of the second aperture unit BE2, which is also advantageously arranged on the base plate BP in a space-saving manner. In this embodiment of the second aperture unit BE2 , the guide device FV is therefore designed to allow only a translation of the at least one further blade WL.

[0080] For an SID of 1000 mm, the blade pair LP1, LP2 of the first aperture unit BE1 is spaced from the X-ray focus RF at a distance of 190 mm to 210 mm, while the aperture of the third aperture unit BE3 is positioned at a distance of approximately 40 mm from the X-ray focus RF. The at least one further blade WL of the second aperture unit BE2 is then positioned at a distance of approximately 244 mm from the X-ray focus RF.

[0081] This embodiment of the second aperture unit BE2 also allows for asymmetrical fading of the blade pairs LP1 and LP2 of the first aperture unit in these two directions. The travel paths of the two additional blades WL1 and WL2 are chosen to be large enough so that they can be positioned completely outside the maximum X-ray field MRS in their rest position. Depending on the application, the additional blades WL1 and WL2 can each supplement one of the blades of the first aperture unit BE1.

[0082] The second aperture unit BE2 represents a simplified possibility for realizing asymmetric fading in the RFU field, offering primarily advantages in terms of installation space and costs compared to typical asymmetric apertures.

[0083] Figure 3 A detailed view of an X-ray collimator RK with precisely one additional blade WL in another embodiment of the present invention is shown. Here, too, the components of the second aperture unit BE2 are arranged on a supporting base plate BP, via which the second aperture unit BE2 can be mounted in the housing of the collimator RK. The additional blade WL is also designed with straight beam edges. However, the outer edges of the additional blades WL are designed in the form of circular arcs. In the figure, the beam edges of the additional blades WL are oriented parallel to the beam edges of the blades of the first aperture unit BE1. The second aperture unit BE2 also includes a guide device FV for adjusting the additional blade WL. The guide device FV is designed to allow translation and / or rotation of at least one additional blade.

[0084] The guide device FV comprises a first guide disk FSH and a second guide disk FSH located above it. Two guide webs FST are mounted parallel to each other on the first guide disk FS. The further blade WL is arranged on the guide web FST so that it can be adjusted in translation. A guide pin FP, arranged laterally on the further blade WL, engages in a guide slot FN in the second guide disk FSH. To cause the further blade WL to translate toward or away from the central beam ZS, a drive device of a drive module AM in the form of an electric motor drives the second guide disk FSH to rotate, thereby adjusting the guide pin FP in the guide slot FN and causing the further blade WL to move along the guide web FST.

[0085] Furthermore, the second aperture unit BE2 is designed to change the angular position of the additional blades WL relative to the blades of the first aperture unit BE1. In other words, the additional blades WL can be rotated about the central beam ZS by means of the guide device FV. To this end, another electric motor EM belonging to the drive module AM of the second aperture unit BE2 can rotationally drive the first guide disk FSH, while another electric motor EM drives the second guide disk FSH synchronously and in the same direction of rotation. This allows the additional blades to assume any angular position relative to the blades of the first aperture unit BE1. The symmetrical fading-in of the blade pairs LP1 and LP2 of the first aperture unit can be further limited to any desired asymmetrical configuration, in particular, thereby also allowing the generation of image fields or ray fields RS having quadrilateral surfaces other than right angles. In particular, the corners of the ray field RS generated symmetrically by the first aperture unit BE can be faded out by the second aperture unit BE2.

[0086] The second aperture unit BE2, including the additional blades WL, offers a very good cost-effectiveness ratio. The possibility of an asymmetric fade-in for one of the four blades of the first aperture unit BE1 is sufficient in many clinical applications. At the same time, the technical complexity, production costs, and required installation space are lower than those for a completely asymmetric aperture system.

[0087] It should be noted that the further blades WL can be rotated continuously by means of the two guide discs.

[0088] As reference Figure 2 and Figure 3 As described, the at least one further blade WL, WL1, WL2 can be designed differently. In particular, the further blade WL, WL1, WL2 can be designed as an X-ray-opaque or at least partially X-ray-opaque blade. This can be in the form of a flat, at least partially X-ray-transparent, X-ray-opaque flat blade or as a partially X-ray-transparent wedge filter. Alternatively, the further blade WL, WL1, WL2 can be designed as a typically X-ray-opaque contour filter with a curved, curved beam edge KF.

[0089] In embodiments with more than one further blade WL, it is particularly advantageous to combine different shapes of the further blades in order to be able to implement a large number of applications with the collimator RK.

[0090] Figure 4A diagram shows an X-ray collimator RK according to the present invention, in another embodiment of the present invention, comprising a storage compartment in the form of a filter magazine M. The filter magazine M is designed to accommodate or store at least three additional blades WL. Furthermore, the X-ray collimator RK includes a replacement device (not shown) associated with the filter magazine for positioning one of the three additional blades in the second aperture unit. The replacement device is designed to transfer one of the additional blades WL from the filter magazine M to the second aperture unit BE2, or vice versa. The replacement device can be designed in various ways, for example, including a magnetic or mechanical coupling mechanism. In the present embodiment, the filter magazine M includes a total of five positions for additional blades. Positions PL1 and PL2 are unoccupied. The remaining positions of the magazine M are occupied by additional blades in the form of X-ray-transparent, X-ray-opaque, flat or wedge-shaped filters F and / or contour filters KF with arbitrarily shaped beam edges.

[0091] The filter magazine M is located outside the collimator housing, specifically in the region of the second aperture unit BE2 in the direction of beam propagation AR. In other words, the filter magazine M is mounted at the level of the second aperture unit BE2, so that the path for additional blades during replacement is advantageously short. The height of the filter magazine M does not exceed the height of the DAP chamber DK, so that the filter magazine does not affect the overall height of the collimator RK.

[0092] The advantage of the filter storage bin M is that it can be used for Figure 2 or Figure 3 Different additional blades WL are stored in the different positioning mechanisms of the second aperture unit BE2 and can be added to the X-ray collimator RK when necessary. This reduces the production costs of the collimator RK because, for example, fewer drives are required. In this way, the diversity of additional blades integrated in the X-ray collimator RK can be increased. The additional free positions PL1 and PL2 in the storage bin M provide the following possibilities: providing parking positions for the replacement process, or subsequently equipping the collimator RK with other additional blades, for example according to individual user preferences. This keeps the variations of the collimator RK itself and the installation of the collimator RK small. For example, after installation, the same X-ray collimator RK is equipped as follows for different users:

[0093] Radiology: Wide wedge foot & contoured filter shoulder

[0094] Urology: Additional fifth blade & narrow wedge.

[0095] Figure 5 In one embodiment, the present invention is shown by means of Figure 2A top view of the asymmetrically faded-in radiation field RS of the aforementioned embodiment variant of the second aperture unit BE2. The asymmetrical fade-in is achieved relative to the largest possible radiation field MRS, in which all blades of the first and second aperture units BE1 and BE2 are in their rest position, i.e., outside the X-ray beam path. A portion of the patient's spine is imaged. The second blade pair LP2 is almost completely in its rest position and accordingly contributes almost nothing to delimiting the radiation field RS, while the first blade pair LP1 is each displaced approximately half the travel distance toward the central beam ZS, resulting initially in a symmetrical, rectangular radiation field RS. Furthermore, another first blade WL1 appears, further delimiting the rectangular radiation field from the right, resulting in a rectangular field of view that is shifted to the left relative to the central beam ZS. The additional second blade essentially corresponds to the associated blade of the second blade pair LP2. It contributes no more to the fade-in of the radiation field RS than the associated blade of the second blade pair LP2.

[0096] The blade pairs LP1 and LP2 consist only of completely radiopaque blades, while the first and second blades WL1 and WL2 are partially radiopaque. These blades allow a portion of the incident X-ray radiation to pass through, allowing the body area covered by the blade WL1 to be detected without fully irradiating the corresponding detector surface. This facilitates the gradual development of a suitable field of view. The blades WL1 and WL2 are currently designed as thin, flat steel blades.

[0097] Figure 6 A top view of an asymmetrically faded radiation field RS according to the invention is shown in an alternative embodiment in radiology. Figure 3 The shoulder joint is shown in the case of the X-ray collimator RK of the second aperture unit BE2. The beam field is initially slightly faded in rectangularly, primarily through the first blade pair LP1, by means of the first and second blade pairs LP2 of the first aperture unit BE1, relative to the maximum square beam field MRS. To improve the image quality, the upper left corner, where no body tissue is present, is now faded out by means of further blades WL in the form of an X-ray-transparent wedge filter F. This can be achieved by Figure 3 The second aperture unit BE2 is simple to implement.

[0098] Figure 7 A top view of an asymmetrically faded radiation field according to the invention is shown in another alternative embodiment in fluoroscopy. Here, the corners of the rectangular radiation field faded in by the first aperture unit can also be additionally faded out via an X-ray-transparent wedge filter F.

[0099] As from Figure 6 and Figure 7 As can be clearly seen, the angular position of the further blade WL / F can be set arbitrarily via the guide device FV of the second aperture unit BE2 .

[0100] Although the details of the present invention have been described in detail through preferred embodiments, the present invention is not limited to the embodiments, and other variations can be derived therefrom by those skilled in the art without departing from the scope of protection of the present invention.

Claims

1. An X-ray collimator (RK) for automatically fading an X-ray field (RS) emitted by an X-ray source (RQ) of an X-ray imaging facility (RB), the X-ray collimator (RK) comprising: - a first aperture unit (BE1), and - second aperture unit (BE2), It is characterized in that The first aperture unit (BE1) is designed to fade the X-ray field (RS) symmetrically with respect to a central ray (ZS) of the X-ray field (RS), and The second aperture unit (BE2) is designed to further limit the symmetrically fading ray field asymmetrically with respect to the central ray (ZS).

2. The X-ray collimator (RK) according to claim 1, characterized in that The second aperture unit (BE2) is arranged downstream of the first aperture unit (BE1) in the radiation propagation direction (AB).

3. The X-ray collimator (RK) according to claim 2, characterized in that The first aperture unit (BE1) includes at least one blade pair (LP1, LP2), wherein the two blades of the at least one blade pair (LP1, LP2) are arranged opposite to each other and are configured to move toward or away from the central ray (ZS) in a coupled manner transversely to the ray propagation direction (AB).

4. The X-ray collimator (RK) according to claim 3, characterized in that The second aperture unit (BE2) comprises at least one further blade (WL, WL1, WL2).

5. X-ray collimator (RK) according to claim 4, characterized in that The second aperture unit (BE2) is designed to adjust the at least one further blade (WL, WL1, WL2) parallel to the blades of the first aperture unit (BE1) and transversely to the beam propagation direction (AB).

6. X-ray collimator (RK) according to claim 4 or 5, characterized in that The second aperture unit (BE2) is designed to change the angular position of the at least one further blade (WL, WL1, WL2) relative to at least one blade pair (LP1, LP2) of the first aperture unit (BE1).

7. X-ray collimator (RK) according to claim 4 or 5, characterized in that The second aperture unit (BE2) comprises a drive module (AM) comprising at least one drive device (EM) for the adjustment movement of the at least one further blade (WL, WL1, WL2).

8. X-ray collimator (RK) according to claim 4 or 5, characterized in that The second aperture unit (BE2) comprises at least one guide device (FV) for the at least one further blade (WL, WL1, WL2), the guide device (FV) being configured to allow a translation and / or rotation of the at least one further blade (WL, WL1, WL2).

9. X-ray collimator (RK) according to claim 4 or 5, characterized in that The at least one further blade (WL, WL1, WL2) is designed as an X-ray-impermeable or at least partially X-ray-transmissive blade (F).

10. The X-ray collimator (RK) according to claim 4 or 5, characterized in that The at least one further blade (WL, WL1, WL2) is designed as a contour filter (KF).

11. X-ray collimator (RK) according to claim 4 or 5, characterized in that The X-ray collimator (RK) further comprises at least one magazine (M) for accommodating at least three further blades (WL, WL1, WL2), wherein the X-ray collimator (RK) comprises an exchange device for arranging one of the three further blades in the second aperture unit (BE2).

12. X-ray collimator (RK) according to claim 11, characterized in that The magazine (M) is arranged on the collimator housing in the region of the second aperture unit (BE2) in the beam propagation direction (AB).

13. X-ray collimator (RK) according to claim 4 or 5, characterized in that The at least one further blade (WL, WL1, WL2) is arranged at a distance of 220 mm to 250 mm.

14. An X-ray imaging facility (RB), characterized in that The X-ray imaging facility (RB) comprises an X-ray collimator (RK) according to any one of claims 1 to 13.

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