US20010005912A1

US20010005912A1 - "Patient bed arrangement for use in an open MR system"

Info

Publication number: US20010005912A1
Application number: US09/739,899
Authority: US
Inventors: Wilhelm Duerr
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1999-12-27
Filing date: 2000-12-20
Publication date: 2001-07-05
Also published as: JP2001198099A; DE19963184A1

Abstract

A patient bed arrangement for use in an intense-field magnet system which generates a vertical basic field for MR imaging, wherein two carrying supports are centrally symmetrically arranged between an upper magnet and a lower magnet of the magnet system, has a longitudinal axis that is oriented at an acute angle β of 45° relative to the connecting axis between the carrying supports.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a patient bed arrangement for use with an intense-field magnet system which generates a vertical basic field, where the magnets are supported by two carrying columns that are centrally symmetrically arranged relative to the magnets between an upper magnet and a lower magnet.

2. Description of the Prior Art

In order to withstand the attraction forces between the upper and the lower magnets in a so-called “open” magnetic resonance (MR) imaging apparatus (which weigh 55 tons given a field intensity of 1 Tesla), an intense-field magnet system which generates a vertical field requires two extremely stable supports. In an apparatus employing superconducting magnets, these supports also serve as a housing for liquid helium conduits, the cryo-shield and the cryostat housing. For reasons of stability, the arrangement normally is symmetrical relative to a center point; this has the disadvantage that the accessibility with respect to the patient on the patient bed is significantly restricted by the supports.

In order to improve this accessibility, European Patent 0 793 941 teaches to move the supports from diametrically opposing positions to positions toward the rear of the apparatus for increasing the openness. It is thus easier to gain access to the patient from the side, which is particularly advantageous with respect to interventional operations. This arrangement, however, has the disadvantage of being mechanically more unstable than the centrally symmetrical arrangement. In this non-centrally symmetrical arrangement, the supports not only are stressed as to compression but also as to bending, since a strong unidirectional bending moment is generated by the magnetic attraction forces. The magnet becomes heavier, larger and more expensive and vibrations coupled in from the outside or by interaction with the gradient fields, are considerably stronger compared to the centrally symmetrical arrangement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a patient bed arrangement of the aforementioned type wherein accessibility to the patient is achieved without the disadvantages of the aforementioned unsymmetrically displaced carrying supports. This object is inventively achieved in a patient bed arrangement wherein the longitudinal axis of the patient bed is oriented toward the connecting axis of the carrying supports by an acute angle β, preferably 45°.

In the aforementioned conventional arrangement having centrally symmetrical carrying supports, longitudinal the axis of the patient bed forms an angle of 90° with the connecting axis of the carrying supports. In the inventive arrangement the orientation of the longitudinal axis of the patient bed to the connecting axis between the supports at a non-90°angle results in as good lateral accessibility to the patient as in the unsymmetrically displaced arrangement, but without the disadvantages of this unsymmetrical carrying support arrangement. The fact that the patient does not have two columns next to him or her, which can cause claustrophobic effects in some cases, but has a maximum of one column next to him or her, since the other one will be toward the bottom end of the bed and is not disturbingly perceived by the patient, is a further benefit of this inventive arrangement.

A further embodiment of the inventive patient bed arrangement has particularly beneficial structure, wherein the patient bed, preferably cantilevered with one arm attached to a lifting support, can be inserted into the intense-field magnet system, The lifting support preferably is fastened at one of the carrying supports, or can be integrated with it, since the carrying supports must be extremely stable by nature due to the magnetic forces and the weight of the magnets

In a further embodiment of the invention, the patient bed can be pivoted around a vertical axis of the lifting support, so that it is possible to move the patient out of the intense field region to a position next to the two carrying supports, at one side. Interventional operations are even more easily conducted in this position.

In order to be able to bring lateral parts of the patient, such as the shoulders, into the imaging region of the intense-field magnet arrangement as well, in a further embodiment of the invention at least one support plate of the patient bed can be additionally displaceable transversely to the insertion axis.

The operating elements and displays can be arranged for easy accessibility at the lifting support or at the appertaining carrying support. The bed lifting motor can be a magnetically shielded electromotor, which is preferably arranged in the lifting support and which has a spindle, or can be a hydraulic drive, which can also be accommodated in the bed base due to its small size, if an unsupported bed is not to be utilized.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic horizontal section through an intense-field magnet system with a centrally symmetrical arrangement of the carrying supports and a conventional patient bed arrangement. [0012]
FIG. 2, corresponding to FIG. 1, is a schematic section through a conventional arrangement with carrying supports that are displaced toward one another. [0013]
FIG. 3 is a side view of the arrangement according to FIG. 2. [0014]
FIG. 4 is a horizontal section through an intense-field magnet system with a first embodiment of an inventive patient bed arrangement. [0015]
FIGS. 5[0016] a through 5 d show another version of the inventive patient bed arrangement in various pivot and displacement positions of the patient bed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, an intense-field magnet system which generates a vertical basic field for MR imaging has a lower magnet [0017] 1, and an upper magnet 5 (see FIG. 3) is fastened above the lower magnet 1 supported by two carrying supports 2. Conventionally, the patient bed arrangement is fashioned as in FIG. 1, i.e., the longitudinal axis 4 of the patient bed, which can be displaced in the direction of this axis 4, is perpendicular relative to the connecting axis of the carrying supports 2.
In the known embodiment shown in FIGS. 2 and 3, the two carrying [0018] supports 2 are displaced toward one another toward the back of the magnet system. This has the disadvantageous consequence that the carrying supports 2 are not only stressed in compression, but also for bending as a result of the weight of the upper magnet 5 and particularly as a result of the magnetic attraction forces between the magnets. In addition, vibrations coupled in from outside or by gradient interaction (indicated by arrows 6 in FIG. 3) are considerably stronger compared to the symmetrical embodiment according to FIG. 1.
In a first inventive embodiment (shown in FIG. 4) of a patient bed arrangement for an intense-field magnet system, the carrying supports are centrally symmetrically arranged so that the carrying supports are diametrically opposite to one another, and the [0019] bed axis 4 forms an acute angle β of 45°with the connecting axis 7 of the carrying supports 2. Therefore, a similarly good, even more improved accessibility results with respect to the patient, since accessibility from the right side is the same as from left and right in FIG. 2, however, completely free accessibility also exists from the left side with respect to the upper head region of the patient, which is not achieved in the arrangement according to FIG. 2 In the inventive arrangement according to FIG. 4, the patient does not have two supports next to him or her in any position, but only one at a maximum, which is more beneficial for claustrophobic patients. In order to receive a maximal transverse displaceability of the patient bed in the direction of double arrow 8, so that lateral body parts of the patient can also be placed in the bed axis 4 and therefore in the imaging volume of the intense-field magnet, the angle β of 45°is particularly beneficial.
In the inventive embodiment according to FIG. 4, the [0020] patient bed 3 is fastened at a lifting support 9 via a support arm, so that it can be displaced from a lowered position, in which the patient can be placed onto the bed 3, into a position above the height of the lower magnet 1. Specific details for displacing the bed in the direction of its longitudinal axis 4, and transverse displaceability in the direction of double arrow 8, are not shown, since such displaceable patient beds are sufficiently known. In FIG. 4, the lifting support 9 is firmly connected to the neighboring carrying support 2, so that anchoring of this lifting support is considerably facilitated, since the carrying support 2, already must be designed to be extremely stable due to the intense forces.
FIGS. 5[0021] a through 5 d show a second embodiment of an inventive patient bed arrangement. Proceeding from the loading and unloading position according to FIG. 5 a, in which the patient bed is moved downwardly, so that the patient can easily reach it, the lifting support 9′ for the patient bed 3, which is connected to the left carrying support 2 and which can be swivelled around a pivot point 10, is initially upwardly moved and then can be placed into the position according to FIG. 5b, for example, in which the patient is situated in the weaker edge field and can be very easily accessed for interventional operations. In order to be placed in the entirely pivoted position (corresponding to FIG. 4), the patient bed must be initially moved back in the direction of its longitudinal axis 4, since it would otherwise bump against the right carrying support 2. It can only be moved back into its forwardly displaced position after it has been swivelled-in sufficiently far, namely somewhat further than in FIG. 5c. The support plate also can be displaced in the direction of the double arrow 8 in this embodiment of an inventive patient bed arrangement.
FIG. 5[0022] d shows a side view of a column 11, which contains suitable lifting and pivoting components, from which the lifting support 9′ extends in cantilevered fashion,
Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art. [0023]

Claims

I claim as my invention:

1. In a magnet system which generates a vertical magnetic field between an upper magnet and a lower magnet and which has two supports connected to said upper magnet and said lower magnet which supports said upper magnet above said lower magnet, said supports being centrally symmetrically disposed relative to said upper magnet and said lower magnet, the improvement comprising:

a patient bed having a longitudinal axis mounted for orienting said longitudinal axis at an acute angle of 45°relative to a connecting axis proceeding between said carrying supports.

2. The improvement of

claim 1

further comprising a lifting support connected at one end of said patient bed for inserting said patient bed between said upper magnet and said lower magnet

3. A patient bed as claimed in

claim 2

wherein said patient bed is insertable between said upper magnet and said lower magnet along an insertion axis, and wherein said patient bed comprises a support plate mounted for displacement transversely relative to said insertion axis.

4. The improvement of

claim 2

wherein said patient bed is pivotable around an axis of said lifting support.

5. The improvement of

claim 2

wherein said lifting support is connected to one of said carrying supports.

6. The improvement of

claim 5

wherein said lifting support has operating components associated therewith, said operating components being disposed at said carrying support to which said lifting support is connected.

7. The improvement of

claim 2

wherein said lifting support is integrated with one of said carrying supports.

8. The improvement of

claim 7

wherein said lifting support has control elements associated therewith and wherein said control elements are disposed at said carrying support with said lifting support is integrated.

9. The improvement of

claim 2

wherein said lifting support has control elements associated therewith, and wherein said control elements are disposed at said lifting support.

10. The improvement of

claim 2

wherein said lifting support has a lifting motor, and further comprising magnetic shielding for said lifting motor in said lifting support.

11. The improvement of

claim 2

wherein said lifting support has a hydraulic lifting motor.

12. The improvement of

claim 11

wherein said patient bed has a bed base, and wherein said hydraulic lifting motor is disposed in said bed base.