DE102013227060A1 - Shooting frame for the gantry of a computer tomograph, as well as gantry and computer tomograph with such a rotating frame - Google Patents

Abstract

The invention is based on the finding that a rotary frame must be designed to be stable, especially in the direction of the centrifugal forces acting upon rotation. Furthermore, the inventors have recognized that with a sufficiently rigid and stiff annular or cylindrical reinforcing frame, the centrifugal forces can cause stabilization of components mounted on the inside of the reinforcing frame. Therefore, according to a first variant, the inventors propose to build up the rotating frame for the gantry of a computer tomograph on a cylindrical basic body (14) with a central axis of rotation. The stability of this basic body is increased by a reinforcing frame with at least two annular reinforcing elements (15), wherein the reinforcing elements (15) are arranged outside the main body (14) and concentric with the central axis of rotation. In this case, the reinforcing elements (15) are connected to the base body (14) in such a way that the reinforcing elements (15) are designed to receive centrifugal forces acting on the base body (14).

Description

The invention relates to a rotating frame for the gantry of a computer tomograph, a gantry for a computer tomograph and a computer tomograph. A computer tomograph is designed for X-ray-related generation of images, in particular sectional images. Computer tomographs are mainly used in medical imaging, but are also used in non-destructive material testing and other technical fields. The images are reconstructed from measurement data, the measurement data comprising projections from a multiplicity of different projection directions. To record the projections from different projection directions, an X-ray source and an X-ray detector cooperating with the X-ray source rotate about a receiving area. In the construction of a computer tomograph, all components that are to be rotatable are used in a so-called rotating frame, in particular the X-ray source and the X-ray detector. Such a rotating frame is also referred to as a "drum" or rotatable part of the gantry of a computer tomograph. This rotating frame is rotatably mounted in a gantry housing. The gantry housing further has a fixed support frame, are attached to the cladding elements or flow plates. In this support frame, in turn, the rotating frame is rotatably mounted, for example by means of a rolling bearing or by means of a magnetic bearing.

In order to avoid motion artifacts in the reconstructed image which may arise due to movements in the recording area, the aim is to make the time window for recording the projections required for the reconstruction as small as possible by means of high rotational speeds. In the current computed tomography devices speeds of 240 U / min are achieved. In the future, however, the speeds should be raised to at least 300 rpm. By combination of high speed, large radius of rotation and high rotational mass of the rotating frame is a mechanically highly stressed component, which must guarantee not only recording the voltages occurring but also compliance with the positions of the X-ray source and X-ray detector, since already position shifts of the components in the submillimeter range to a significant impairment image quality. Essential requirements of the rotating frame are therefore a high stability, in particular a high strength and rigidity, in order to minimize deformation of the rotating frame and thus the positional displacements of the components for recording the projections.

The rotating frame is therefore regularly produced as a metal casting, especially as cast aluminum. The increase in the stability of the rotating frame by a solid construction of the rotating frame, however, results in a higher cost of materials and higher weight. Then also components for driving the rotor and the gantry housing would have to be adapted to the larger weight forces and the resulting larger centrifugal forces. In DE 10 2008 036 019 A1 It is therefore proposed to manufacture the rotating frame from a particle-reinforced metal-matrix composite.

It is therefore an object of the present invention to specify how the rotating frame of the gantry of a computer tomograph can be formed in a technically simple manner as possible. This object is achieved by a rotating frame according to claim 1 and according to claim 2, by a gantry according to claim 8, and by a computer tomograph according to claim 11.

The invention is based on the finding that a rotary frame must be designed to be stable, especially in the direction of the centrifugal forces acting upon rotation. Furthermore, the inventors have recognized that with a sufficiently rigid and stiff annular or cylindrical reinforcing frame, the centrifugal forces can cause stabilization of components mounted on the inside of the reinforcing frame. Therefore, according to a first variant, the inventors propose to build up the rotating frame for the gantry of a computer tomograph on a cylindrical basic body with a central axis of rotation. The stability of this base body is increased by a reinforcing frame with at least two annular reinforcing elements, wherein the reinforcing elements are arranged outside the base body and concentric with the central axis of rotation. In this case, the reinforcing elements are connected to the base body in such a way that the reinforcing elements are designed to receive centrifugal forces acting on the base body. The first variant of the solution according to the invention is technically particularly easy to implement.

Furthermore, the annular reinforcing elements do not extend over the entire extent of the cylindrical base body along the axis of rotation. Therefore, material is saved over a conventional solid construction, so that the rotary frame according to the invention has a particularly low weight. An inventive rotary frame can thus be designed so that it can realize particularly high speeds by a particularly high stability with comparatively low weight.

The stability of the rotating frame, in particular against forces that can cause distortion of the rotating frame is further increased by cross members are at least partially disposed between the base body and the reinforcing elements, wherein the cross member along the central axis of rotation are oriented. The cross member serve on the one hand, the distribution of centrifugal forces acting on the body centrifugal forces on the reinforcing elements, on the other hand, the inclusion of forces, which could lead to a torsion of the rotating frame without the cross member.

In a second variant of the invention can be dispensed with the cylindrical base body of the rotary frame. In this case, the reinforcing frame comprises at least two concentric with a central axis of rotation arranged annular reinforcing elements and along the central axis of rotation oriented cross member. The reinforcing elements are in such a way with the cross beams in connection that the reinforcing elements are designed to receive centrifugal forces acting on the cross member. Due to the lattice-like structure which is formed by the reinforcing elements and the cross members, the reinforcing frame has sufficient stability even without a cylindrical base body. This second variant of the solution according to the invention is technically easy to implement and allows to produce a rotating frame with a particularly low weight.

The reinforcing frame can in particular be designed so that the reinforcing elements are positively connected to the cross members. As a result, the reinforcing frame and thus also the rotary frame on a particularly high stability.

In accordance with a further aspect of the invention, the cross members may each have first recesses on the side facing the reinforcing elements, wherein the reinforcing elements have second recesses at connection points to the cross members, so that a plug connection between the reinforcing elements and the cross members is formed. Such a connector is technically easy to implement and in particular has the advantage of easy installation of the rotating frame with high stability.

It is further provided that the rotating frame within the reinforcing frame can have at least one adapter for integrating electronic components. Such an adapter makes it possible to integrate a necessary for a tomographic image electronic component such as an X-ray source or an X-ray detector in a technically simple manner in the rotating frame.

According to a further aspect of the invention, at least one reinforcing element is designed as a rotor of an electric motor. Thereby, a further weight advantage is achieved because a drive component, namely the rotor, at the same time fulfills the function as part of the reinforcing frame to stabilize the rotating frame.

Furthermore, the invention comprises a gantry for a computer tomograph with a rotary frame according to the invention and a support frame, wherein the rotary frame is rotatably mounted on the support frame via an outer bearing. Alternatively, the rotary frame may be rotatably supported via an inner bearing on the support frame. In both types of storage, the low weight of the rotary frame according to the invention has an advantageous effect on the design of the gantry and in particular of the support frame. Because of the low weight of the rotating frame, the forces acting on the support frame forces are lower, so that the support frame of a gantry invention can be made with less material than a conventional support frame.

One aspect of the invention relates to a gantry with drive elements, wherein the drive elements are adapted to set the rotating frame by belt drive in a rotational movement about the central axis of rotation. Such a belt drive is technically particularly easy to implement. Thus, this embodiment of a gantry is a technically particularly simple and at the same time stable and reliable and cost-effective solution.

If the rotating frame is designed so that it achieves particularly high rotational speeds due to its particularly high stability with comparatively low weight, then this makes it possible for the CT scanner to take pictures with a higher time resolution.

In the following the invention will be described and explained in more detail with reference to the embodiments illustrated in the figures.

Show it:

1 a computer tomograph according to the invention,

2 a rotating frame according to the first variant of the invention,

3 a rotating frame according to the second variant of the invention,

4 a reinforcing element in cross-section,

5 a rotating frame with a cross member in longitudinal section,

6 a rotating frame without cross member in longitudinal section,

7 a rotary frame with a cross member and centrally arranged outer bearing in longitudinal section,

8th a rotating frame with a cross member and laterally arranged outer bearing in longitudinal section,

9 a rotating frame with a cross member and with a bottom bracket in longitudinal section,

10 a rotating frame with a cross member and with an adapter for the integration of electronic components in longitudinal section,

11 a reinforcing element with wrapped copper conductors in cross section, and

12 a rotating frame with cross member and with an electric motor drive in longitudinal section.

1 shows a computer tomograph according to the invention. The computed tomography includes a gantry 1 with a rotating frame 4 , In the rotating frame 4 are an X-ray source in the example shown here 8th and one with the X-ray source 8th interacting x-ray detector 9 integrated. The rotating frame 8th rotates during the acquisition of X-ray projections around a longitudinal axis 5 , and the X-ray source 8th emit X-rays during recording 2 in the form of an x-ray beam. In particular, the x-ray beam may be formed as a fan or cone. The CT scanner can also have more than just an X-ray source 8th and more than just an x-ray detector 9 have to enable recordings in the so-called dual energy method. At the X-ray source 8th In the example shown here, this is an X-ray tube. In the case of the X-ray detector 9 In the example shown here, this is a line detector with several lines, for example 128 lines or 256 lines.

Upon rotation of the rotating frame 4 X-ray projections can be taken from different directions, which can be reconstructed into a high-resolution, spatially three-dimensional image. When taking the X-ray projections in the example shown here is a patient 3 on a patient couch 6 which is so connected to a lying base that he is the patient bed 6 with the patient 3 wearing. The patient bed 6 is designed for the patient 3 along a take-up direction through the opening 10 the gantry 1 method. The pickup direction is usually through the axis of rotation 5 of the rotating frame 4 given. However, the rotation axis 5 also opposite the recording direction, along which the patient 3 while recording is being moved, be tilted, for example, by the rotating frame 4 is designed as part of a tiltable gantry.

In the example shown here, the computer tomograph also includes a computer 12 , which is designed for example for controlling the computed tomography and for storing and processing a plurality of X-ray projections. The computer 12 is with an output unit 11 , For example, connected to the graphical output of tomographic images. At the output unit 11 For example, it is an LCD, plasma or OLED screen. Furthermore, the computer 12 with an input unit 13 connected. At the input unit 13 For example, it is a keyboard, a mouse, a so-called touch screen or even a microphone for voice input. interfaces 7 allow the computer 12 with the computer tomograph and with the input unit 13 or an output unit 11 to be able to communicate. At the interfaces 7 These are generally known hardware or software interfaces, eg the hardware interfaces PCI bus, USB or Firewire.

2 shows a rotating frame according to the first variant of the invention. In the embodiment of the first variant of the invention shown here, the rotating frame comprises 4 a cylindrical body 4 and three annular reinforcing elements 15 which are concentric with the axis of rotation 5 of the basic body 4 are arranged. Furthermore, the reinforcing elements 15 the same outer radius and substantially the same inner radius. The inner radius of the reinforcing elements 15 only know at the connection points to the cross members 16 through internal recesses deviations from a fixed value. The reinforcing elements 16 can, as shown here, be elongated and provided with flat, straight surfaces. In various embodiments of the invention, the reinforcing elements 16 formed substantially cuboid, with deviations from the cuboid shape by recesses at the connection points to the reinforcing elements 15 or a slightly curved and attached to the outer surface of the main body 14 adapted contour can be justified. The two reinforcing elements 15 shape together with the direction of the axis of rotation 5 oriented cross members 16 a reinforcing frame, which outside the main body 14 is arranged. The crossbeams 16 are in the direction of the axis of rotation 5 oriented that the axis of its longest extent in the direction of the axis of rotation 5 are oriented, in particular, this longest axis can be oriented parallel to the axis of rotation. This reinforcing frame forms a grid-like structure and is connected to the main body 14 in such a way that when rotating about the axis of rotation 5 on the main body 14 acting centrifugal forces can be at least partially transmitted to the reinforcing frame. The crossbeams 16 can be fixed by joining techniques such as welding or gluing to the base body 14 be connected.

The main body 14 is typically made of sheet metal, such as sheet steel. Alternatively, the main body 14 also be made from a semi-finished product. The thickness of a basic body 14 may vary between less than one millimeter and several millimeters in various embodiments. According to one aspect of the invention, the thickness of the base body is 14 one to two millimeters. In the established aluminum casting process, a comparable cylindrical element of a conventional revolving frame is many times thicker. For technical reasons, aluminum casting is usually at least 15 millimeters thick. Even considering the low density of aluminum compared to steel sheet, the construction according to the invention brings with it a considerable weight advantage. The main body 14 can, as in 2 shown forming a complete cylinder; In further embodiments, the main body 14 However, recesses and / or holes in its cylindrical basic shape, for example, to attach power lines, coolant lines and other supply channels between inside and outside of the body attached elements in a simple manner.

The main body 14 may further be made of a non-metallic material, such as carbon fiber, composite or plastic. The main body 14 must have sufficient stability to prevent it from operating the revolving frame 4 tears or deforms so much that it results in artifacts in the imaging. The exact stability of the body 14 , in particular the exact strength and rigidity, depends on the design of the reinforcing frame. The material of the basic body 14 and its thickness also depend on the diameter of the body 14 with a large diameter typically associated with a particularly stable material and / or a high thickness. In the field of medical imaging, the diameter of the basic body is 15 and the reinforcing frame in about 1 to 1.6 meters, wherein in other embodiments of the invention, both larger and smaller diameter can be realized.

The reinforcing elements 15 have a higher stability than the main body 14 on. Therefore, the reinforcing elements 15 preferably made in one piece, ie without welding, gluing or another joining technique. However, it can also be several one-piece reinforcing elements 15 connected to each other, see for example 12 , The reinforcing elements 15 can be made of a metal casting, such as aluminum, or by a milling process. The typical extension of a reinforcing element 15 along the axis of rotation 5 is about one to two centimeters. If a particularly high stability is desired, the expansion of the reinforcing elements 15 along the axis of rotation 5 also be bigger. In the radial direction, the reinforcing elements carry 15 typically a few inches up. In a particularly stable embodiment of the invention wear the reinforcing elements 15 more than 10 inches on.

3 shows a rotating frame according to the second variant of the invention. In this second variant of the invention is based on a cylindrical body 14 waived. The rotating frame 4 then has a reinforcing frame with at least two reinforcing elements 15 and several crossbeams 16 , wherein the reinforcing elements 15 in such a way with the crossbeams 16 related to that the reinforcing elements 15 for receiving on the cross member 16 acting centrifugal forces are designed. This is at least a part of the cross member 16 on the inside of the reinforcing elements 15 ,

In a typical embodiment of the second variant of the invention, the reinforcing elements 15 the same outer diameter and substantially the same inner diameter. Become more than two reinforcing elements 15 so they can be used along the axis of rotation 5 have the same distance from each other, so that a uniform possible transmission of centrifugal forces of the body 14 or from the cross members 16 on the reinforcing elements 16 is guaranteed. Furthermore, the cross member 16 and the reinforcing elements 15 be firmly connected by joining techniques such as welding or gluing to the stability of the reinforcing frame and thus the rotating frame 4 to increase.

The crossbeams 16 can as well as the reinforcing elements 15 be made of a metal casting and must have a high stability. The crossbeams 16 extend typically over the entire extent of the body 14 along the axis of rotation 5 , Regardless of whether the rotating frame 4 a basic body 14 or not, the cross member 16 the same extent along the axis of rotation 5 have or even formed substantially identical, so as even as possible power transmission from the cross members 16 on the reinforcing elements 15 is possible.

4 shows a reinforcing element in cross section, ie in a section through a plane perpendicular to the axis of rotation 5 , In the embodiment shown here, the reinforcing element 15 on its inside rectangular recesses in a regular arrangement. The recesses are dimensioned so that a precisely fitting arrangement of a cross member 16 in a recess of the reinforcing element 15 is possible. Such a reinforcing element 15 can in a development of the rotary frame according to the invention 4 be used, the cross member 16 each on the reinforcing elements 15 facing side first recesses, so that a positive connection between the reinforcing elements 15 and the crossbeams 16 can be formed. Such a positive plug connection is technically particularly easy to implement and allows the rotating frame 4 particularly stable form.

The recesses may be used in further embodiments of the reinforcing element 15 also have other than rectangular shapes, for example, they may be formed trapezoidal in cross section. Furthermore, the recesses may be arranged irregularly, for example because in a certain area of the rotating frame 4 higher centrifugal forces than in other areas are to be expected, so that at the specific area a higher density of connectors with cross members 16 is desired. Higher centrifugal forces are to be expected, for example, if a particularly heavy electronic component is integrated in a certain area.

5 shows a rotating frame with a cross member in longitudinal section. Here are both in 2 dashed line V as well as the central axis of rotation 5 in the cutting plane. In the example shown here, the reinforcing elements carry 15 - Measured against the distance from the axis of rotation 5 - just as high as the crossbeams 16 , In further embodiments, the reinforcing elements 15 and the crossbeams 16 also different high, in principle, both the reinforcing elements 15 as well as the crossbeams 16 can apply higher. Higher reinforcing elements 15 can be beneficial if the reinforcing elements 15 formed as part of a camp, as described in the in 7 to 9 the examples described is the case. In the in 5 Illustrated example are the reinforcing elements 15 as well as the crossbeams 16 connected by plug connections. Furthermore, the cross member 16 firmly with the main body 14 connected, so that the connectors are formed positively.

6 shows a rotating frame without cross member in longitudinal section. Here are both in 2 dashed line VI as well as the central axis of rotation 5 in the cutting plane. In the embodiment shown here, the reinforcing elements 15 firmly with the main body 15 connected, causing the revolving frame 4 obtains a particularly high stability. In further embodiments, between the main body 4 and the reinforcing elements 15 Also be mounted a connecting element, in particular for connection of the reinforcing element 15 with the main body 14 ,

7 shows a rotating frame with a cross member and with centrally located outer bearing in longitudinal section. The outer bearing shown here is a wire roller bearing, wherein the spherical rolling elements 23 such between the central reinforcing element 15 and the central frame 25a which is fixed to the gantry support frame 1 is connected, are arranged, so that the rolling elements 23 a rotation of the rotating frame 4 around the axis of rotation 5 enable. The wires 26 extend along the central reinforcing element 15 around the axis of rotation 5 and form a cage in which the rolling elements 23 to run. The construction shown here has a low weight and is very inexpensive.

8th shows a rotating frame without cross member and with laterally arranged outer bearing in longitudinal section. The outer bearing comprises two wire rolling bearings with the rolling elements 23 and the wires 26 , which in each case the rotation of two decentralized reinforcing elements 15 and thus the rotating frame 4 around the axis of rotation 5 enable. Here is the decentralized frame 25b fixed to the gantry's support frame 1 connected. The construction shown here has the advantage of a particularly high stability of the rotational movement. In further embodiments, more than two wire rolling bearings can be used.

9 shows a rotating frame with a cross member and with a bottom bracket in longitudinal section. The inner reinforcing element 15 is in the example shown here by means of a rolling bearing with rolling elements 23 and the inner frame 25c for rotation about the axis of rotation 5 designed. In this case, the rotational movement is accomplished by a belt drive, wherein the bearing surface for the belt through the profiled surface transversely to the section plane shown here of the inner reinforcing element 15 is shown. Such a surface is particularly suitable for interacting with a V-belt. In this case, the V-belt transmits the rotational movement of an engine to the rotating frame 4 , Alternatively, the surface of the inner reinforcing element 15 have transverse ribs along the cutting plane shown here, whereby the reinforcing element 15 Particularly well with a toothed belt for transmitting the rotational movement can interact. Furthermore, the shown here and other forms of storage such as magnetic bearing principle with different drive types such as belt drive or an electric motor drive can be combined. In particular, the various forms of storage and the drive can be combined both with a rotating frame 4 with basic body 14 as well as without basic body 14 realize.

10 shows a rotating frame with a cross member and with an adapter for integration of electronic components. An electronic component can be an X-ray source 8th , an x-ray detector 9 or other powered components necessary to acquire a tomographic image. The adapter 19 is designed so that it firmly on the one hand with the main body 14 or the reinforcing frame, and on the other hand, that it has a certain electronic component in the rotating frame 4 can integrate. This may be the adapter 19 at least partially comprise the electronic component and / or its shape design may be adapted to the respective electronic component. In particular, the adapter 19 be firmly connected to an electronic component. Furthermore, the adapter 19 be designed to provide a connection, for example for an electronic power supply, for each integrated electronic component.

11 shows a reinforcing element with wrapped copper wires. The reinforcing element shown here 15 is with copper wires 26 wrapped so that the reinforcing element 15 as a rotor 20 an electric motor can be used. It can also be other materials than copper for a wrap of the reinforcing element 15 are used, which are suitable for the reinforcing element 15 as a rotor 20 form an electric motor.

12 shows a rotating frame with an electric motor drive. The electromotive drive is based on a stator 21 as well as a rotor 20 , where the rotor 20 a plurality of interconnected reinforcing elements 15 includes. The individual reinforcing elements 15 are made of so-called electric sheet, which is soft magnetic and is usually made of steel. But there may also be other suitable materials for the production of the individual sheets 27 be used. The to a reinforcing element 15 assembled sheets 27 are, as in 10 shown with a wire 26 wrapped. The design of a rotor 20 through several sheets 27 instead of going through a massive core with beneficial magnetic properties 20 of the rotor 20 associated. In particular, by connecting several sheets 27 Eddy currents avoided. The stator 21 is fixed to the support frame of the gantry 1 connected.

It will be understood by those skilled in the art that the various embodiments described herein may in principle be combined with each other insofar as it appears technically meaningful to those skilled in the art.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008036019 A1 [0003]

Claims (11)

Rotating frame ( 4 ) for the gantry ( 1 ) of a computer tomograph comprising a cylindrical basic body ( 14 ) with a central axis of rotation ( 5 ), and comprising a reinforcing frame with at least two annular reinforcing elements ( 15 ), wherein the reinforcing elements ( 15 ) outside the main body ( 14 ) and concentric with the central axis of rotation ( 5 ) are arranged, wherein the reinforcing elements ( 15 ) in such a way with the main body ( 14 ) that the reinforcing elements ( 15 ) for receiving on the base body ( 14 ) acting centrifugal forces are designed. Rotating frame ( 4 ) for the gantry ( 1 ) of a computer tomograph comprising a reinforcing frame with a central axis of rotation ( 5 ), wherein the reinforcing frame at least two concentric with the central axis of rotation ( 5 ) arranged annular reinforcing elements ( 15 ) and along the central axis of rotation ( 5 ) oriented cross beams ( 16 ), wherein the reinforcing elements ( 15 ) in such a way with the cross beams ( 16 ) that the reinforcing elements ( 15 ) for receiving on the cross member ( 16 ) acting centrifugal forces are designed. Rotating frame ( 4 ) according to claim 1, further comprising at least partially between the main body ( 14 ) and the reinforcing elements ( 15 ) arranged cross member ( 16 ), the cross members ( 16 ) along the central axis of rotation ( 5 ) are oriented. Rotating frame ( 4 ) according to claim 2 or 3, wherein the reinforcing elements ( 15 ) positively with the cross beams ( 16 ) are connected. Rotating frame ( 4 ) according to claim 4, wherein the cross members ( 16 ) on each of the reinforcing elements ( 15 ) facing side first recesses, wherein the reinforcing elements ( 15 ) second recesses at connection points to the cross members ( 16 ), so that a plug connection between the reinforcing elements ( 15 ) and the cross beams ( 16 ) is formed. Rotating frame ( 4 ) according to any one of claims 1 to 5, comprising at least one adapter (within the reinforcing frame) ( 19 ) for the integration of electronic components. Rotating frame ( 4 ) according to one of claims 1 to 6, wherein at least one reinforcing element ( 15 ) as a rotor ( 20 ) is formed of an electric motor. Gantry ( 1 ) for a computer tomograph comprising a rotating frame ( 4 ) according to one of claims 1 to 7 and a support frame, wherein the rotating frame ( 4 ) is rotatably mounted on the support frame via an outer bearing. Gantry ( 1 ) for a computer tomograph comprising a rotating frame ( 4 ) according to one of claims 1 to 7 and a support frame, wherein the rotating frame ( 4 ) is rotatably supported via an inner bearing on the support frame. Gantry ( 1 ) for a computer tomograph comprising a rotating frame ( 4 ) according to one of claims 1 to 6, wherein the gantry drive elements, wherein the drive elements are adapted to the rotating frame ( 4 ) by belt drive in a rotational movement about the central axis of rotation ( 5 ) to move. Computer tomograph with a gantry ( 1 ) according to any one of claims 8 to 10.

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