WO2016058813A1

WO2016058813A1 - Aligning a patient within an mr scanner

Info

Publication number: WO2016058813A1
Application number: PCT/EP2015/072209
Authority: WO
Inventors: Erkki Tapani VAHALA; Matti WAHLSTRÖM
Original assignee: Koninklijke Philips N.V.
Priority date: 2014-10-16
Filing date: 2015-09-28
Publication date: 2016-04-21

Abstract

The invention pertains to aligning a patient within an MR scanner. For that, a system for aligning a patient within an MR scanner (3) is provided, comprising a tabletop (1) on which a patient (2) may be supported, and an indication device for sending out a visible indication signal onto at least a part of the patient's body supported on the tabletop (1). The tabletop (1) and the indication device are configured in such a way that in a predetermined area of the tabletop (1) the indication device may be attached to the tabletop (1) in a predetermined position and orientation in a fixed manner. Preferably, the indication device is part of an RF coil holder (7) that may be attached to the tabletop (1). In this way, reliable possibility for aligning a patient within an MR scanner (3) is provided which may be realized in an easy and cost efficient way.

Description

Aligning a patient within an MR scanner

FIELD OF THE INVENTION

The invention pertains to a system for aligning a patient within an MR scanner, an MR scanner system with an MR scanner including an MR bore and a system for aligning a patient within the MR scanner, and a method for generating a visible indication signal for aligning a patient within an MR scanner.

BACKGROUND OF THE INVENTION

In some MR (magnetic resonance) applications, especially in MR RT

(magnetic resonance radio therapy) applications, patient positioning requires high accuracy. There are commercial units known from conventional practice in which external laser bridges are used for aligning and marking a patient in an MR scanner. For marking a patient in an MR scanner, especially two different cases may be distinguished:

An indication device for sending out a visible indication signal, e.g. a laser sending out a laser beam, may be used to position a patient in such a way that a cross hair formed by the laser falls on a patient's tattoo. In this way, the patient may be correctly positioned in the MR scanner for image acquisition before acquiring an image from the requested location.

Alternatively, a patient may be scanned in an MR scanner, and the acquired image may be used to deduce where to put a tattoo on the patient's skin. In this situation the indication device is used to indicate where to place the tattoo on the patient's skin after acquiring the image in the MR scanner.

These scenarios are referred to as relative marking and absolute marking, respectively.

The accuracy requirements for such marking are very demanding, especially in absolute marking scenarios, where a tabletop on which the patient may be supported must be controlled within a distance of typically less than 2 mm. This means that registration inaccuracy of images taken within the MR bore to the indication device outside the bore must be under control. In a system like the one mentioned above, the laser bridge and the MR scanner are decoupled and need to be calibrated separately. To maintain calibration, mechanical fixtures and moving parts need to be accurate within a couple of millimeters. Such accuracy requirements increase the costs of the system and lead to fragile operating conditions, complex quality assurance procedures spanning over several sub-systems like lasers, floor, patient support mechatronics, MR bore, gradient coil alignment etc. Conventional diagnostics MR scanners are not equipped with patient support mechatronics which are able to provide the necessary accuracy without extensive and costly modifications.

From GB 2 149 510 A a patient alignment system for an MR system is known. A patient transport system is provided in longitudinal alignment with the MR bore. The transport system is capable of retrievably positioning the patient in the active region of the magnetic field and includes first and second assemblies for projecting first and second visible patterns on the skin of the patient. The second pattern is movable vertically within a predetermined range relative to a fixed reference point.

Further, WO 2012/080984 Al describes a radiation therapy planning and follow-up system which includes an MR scanner with a first bore which defines an MR imaging region and a functional scanner, e.g. a nuclear imaging scanner, or a CT scanner with a second bore which defines a nuclear or CT imaging region. A radiation therapy type couch moves linearly through the MR imaging region along an MR longitudinal axis and the nuclear or CT imaging region along a nuclear or CT longitudinal axis which is aligned with the MR longitudinal axis. A fusion processor combines an image representation generated from data collection in the MR imaging region and an image representation generated from data collection in the nuclear or CT imaging region into a composite image representation and a planning processor generates a radiation therapy treatment plan according to the composite image.

US 2011/0306863 describes a patient alignment system for diagnostic and therapeutic procedures where the embodiment is mounted or referenced to the patient positioning interface such as add-on positioning devices or directly with the diagnostic and/or therapeutic treatment table or couch.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a reliable possibility for aligning a patient within an MR scanner which may be realized in an easy and cost efficient way. This object is achieved by the subject matter of the independent claims.

Preferred embodiments of the invention are described in the sub claims.

According to one aspect of the present invention, the object is achieved by a system for aligning a patient within an MR scanner, the system comprising:

a tabletop on which a patient may be supported, and

an indication device for sending out a visible indication signal onto at least a part of the patient's body supported on the tabletop, wherein

the tabletop and the indication device are configured in such a way that in a predetermined area of the tabletop the indication device may be attached to the tabletop in a predetermined position and orientation in a fixed manner.

Accordingly, it is an idea of the invention that the indication device is integrated into the MR system, i.e. attached to the tabletop for the MR system, in a predetermined position and orientation in a fixed manner. In this way, for the indication device and the MR system, i.e. the tabletop, the same coordinate system may be used without the need of extra calibration. This means that accuracy may be highly improved without great effort.

Accordingly, the invention is based on the fact that the relation between the tabletop and its fixed accessories does not change. Therefore, aligning and marking may be made in relation to the tabletop, and, thus, no separate calibration for the indication device and the MR system, respectively, is required.

In general, the indication device may be attached to the tabletop without any other additional device. However, according to a preferred embodiment of the invention, the indication device is part of a frame which is configured for being attached to the tabletop.

In this respect, it is especially preferred that the frame is part of an RF (radio frequency) coil holder. This has the advantage that a device which is needed for acquiring an image with the MR scanner anyway is used for attaching the indication device to the tabletop which reduces the additional effort to realize the invention. Since the attachment of an RF coil has to be done in a predetermined position and orientation, too, the RF coil holder is provided with all prerequisites which have to be met for a frame the indication device is part of.

Generally, the frame the indication device is part of may be attached to the tabletop in different ways. In this respect, according to a preferred embodiment of the invention, the tabletop comprises fixing holes for mechanically attaching and fixing the frame onto the tabletop. This provides for easy attachment and detachment of the frame onto or from the tabletop, respectively, while assuring that an exact positioning of the frame relative to the tabletop may be ensured. Such fixation can re-utilize existing tabletop indexing mechanisms, which are conventionally used for patient fixation.

The indication device may comprise different types of light sources. However, according to a preferred embodiment of the invention, the indication device comprises at least one laser. According to an even more preferred embodiment of the invention, the indication device actually comprises at least two lasers. These lasers are preferably adapted for sending out laser light in two different light planes, respectively.

For some applications, it may be sufficient if the lasers are fixed relative to the frame. However, according to a preferred embodiment of the invention, the lasers are movable in at least two different directions back and forth. In this way, relative and absolute marking requirements can be met in an easy and reliable way.

For deducing the tabletop position relative to the rest of the MR system, there are different solutions. According to a preferred embodiment of the invention, the tabletop comprises markers for MR imaging. This means, that the tabletop is provided with such markers that can be discovered in an image required by the MR system.

In this respect, it is especially preferred that the markers for MR imaging are provided in the predetermined area for attaching the indication device or are provided on a tabletop extension, preferably on an extendable arm. The latter is especially preferred in such situations in which the tabletop itself can move outside the imaging volume of the MR system.

According to another aspect of the present invention, above mentioned object is achieved by an MR scanner system with an MR scanner including an MR bore and a system for aligning a patient within the MR scanner as described above, wherein

the tabletop and the indication device are configured to be movable inside and outside the MR bore, respectively.

In this regard, it is especially preferred that positioning electronics, preferably comprising a position encoder, a laser interferometer or/and a machine vision system, are provided for deducing the tabletop position relative to the MR bore.

According to yet another aspect of the present invention, above mentioned object is achieved by a method for generating a visible indication signal for aligning a patient within an MR scanner, the method comprising the following steps:

providing a tabletop on which a patient may be supported, providing an indication device for sending out a visible indication signal onto at least a part of the patient's body supported on the tabletop,

attaching the indication device in a predetermined area of the tabletop in a predetermined position and orientation in a fixed manner, and

sending out the visible indication signal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. Such embodiments do not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

In the drawings:

Fig. 1 schematically shows an MR scanner system according to a preferred embodiment of the invention,

Fig. 2 schematically shows the tabletop of the MR scanner system according to a preferred embodiment of the invention in a perspective view,

Fig. 3 schematically shows the attachment of an RF coil holder onto the tabletop of the MR scanner system according to a preferred embodiment of the invention in a perspective view,

Fig. 4 schematically shows the RF coil holder of the MR scanner system according to a preferred embodiment of the invention with three fixed lasers for relative marking in a perspective view,

Fig. 5 schematically shows the RF coil holder of the MR scanner system according to a preferred embodiment of the invention with three automatically movable lasers for absolute marking in a perspective view, and

Fig. 6 schematically shows the RF coil holder of the MR scanner system according to a preferred embodiment of the invention with three manually movable lasers for absolute marking in a perspective view.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 schematically shows an MR scanner system according to a preferred embodiment of the invention, with a tabletop 1 on which a patient 2 is supported and an MR scanner 3 with an MR bore 4 for acquiring an image based on the MRI (magnetic resonance imaging) technique. The tabletop 1 is movably supported by a tabletop support 5 which allows the tabletop 1 to be moved inside and outside the MR bore 4 as indicated by the arrow. Positioning electronics 15 in the form of a machine vision system is provided for deducing the position of the tabletop 1 relative to the MR bore 4.

According to the preferred embodiment of the invention depicted in Fig. 1, an RF coil 6 is provided which is mounted on an RF coil holder 7. The RF coil holder 7 itself is attached to a tabletop 1 by pins 8 which are arranged at the feet 9 of the RF coil holder 7. These pins 8 are introduced in fixing holes 10 which are provided in the tabletop 1 as shown in Figs. 2 and 3.

In Fig. 2, it is further shown that the tabletop 1 is provided with markers 11 for MR imaging, i.e. markers which may be identified on an image acquired with the MR system. This serves for deducing the position of the tabletop relative to relative to the MR bore 4.

Further, the usable area for marking and imaging is indicated as a grey area 12 on the tabletop 1 which makes it easier to position the patient 2 on the tabletop 1 in a correct way for marking and/or imaging.

While Figs. 1 and 3 only show the RF coil holder 7 without explicitly providing details with respect to any indication device for marking, Figs. 4, 5 and 6 show the use of three lasers as indication devices according to different embodiments of the invention.

Fig. 4 shows the use of three lasers which send out laser light in three different light planes, respectively. These lasers 12 are provided in different bars of the RF coil holder 7. In this way, within the volume covered by the RF coil holder 7, the lasers 12 may be used for indicating any marking spot within this volume. According to the embodiment shown in Fig. 4, the lasers 12 are fixed and, thus, the RF coil holder 7 according to this embodiment of the invention may be used for relative marking, i.e. the laser beams sent out by the laser 12 may be used to position the patient 2 in such a way that a cross hair formed by the laser beams falls on a tattoo on the skin of the patient 2. In this way, the patient 2 may be correctly positioned in the MR scanner 3 for image acquisition before acquiring an image from the respective location.

In contrast to that, the embodiments of the invention shown in Figs. 5 and 6 may be used for absolute marking, where the patient 2 is scanned in the MR scanner 3, and the acquired image is be used to deduce where to put a tattoo on skin of the patient 2. In this situation, laser 13, 14 are used to indicate where to place the tattoo on the skin of the patient 2 after acquiring the image in the MR scanner 3. For that, the lasers 13 of the embodiment shown in Fig. 5 are movable along different directions along the respective bars of the RF coil holder 7. According to the embodiment shown in Fig. 5, an automatic movement of the lasers 13 is provided for, i.e. by small electric motors not shown in detail. In contrast to that, according to the embodiment shown in Fig. 6, a manual movement of the lasers 14 is provided. Compatibility with the MR system may require powering off the lasers 12, 13, 14 and/or motors during imaging - even with MR compatible piezo motors. The mechanical version for manual movement of the lasers 14, a low-cost system comprises rulers next to the lasers 14 and an in-room display for manually adjusting and locking thumb-controls for the lasers 14 in place.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

REFERENCE SYMBOL LIST

1 tabletop

2 patient

3 MR scanner

4 MR bore

5 tabletop support

6 RF coil

7 RF coil holder

8 pins

9 feet

10 fixing holes

1 1 markers for MR imaging

12 lasers

13 lasers

14 lasers

Claims

CLAIMS:

1. A system for aligning a patient within an MR scanner (3), the system comprising:

a tabletop (1) on which a patient (2) may be supported, and

an indication device for sending out a visible indication signal onto at least a part of the patient's body supported on the tabletop (1), wherein

the tabletop (1) and the indication device are configured in such a way that in a predetermined area of the tabletop (1) the indication device maybe attached to the tabletop (1) in a predetermined position and orientation in a fixed manner, wherein the indication device is part of a frame which is configured for being attached to the tabletop (1) and wherein the frame is part of an RF coil holder (7).

2. The system according to claim 1, wherein the tabletop (1) comprises fixing holes (10) for mechanically attaching and fixing the frame onto the tabletop (1).

3. The system according to any of the preceding claims, wherein the indication device comprises at least two lasers (12, 13, 14) which are adapted for sending out laser light in two different light planes, respectively.

4. The system according to claim 3, wherein the lasers (13, 14) are movable in two different directions back and forth, respectively.

5. The system according to any of the preceding claims, wherein the tabletop (1) comprises markers (11) for MR imaging. 6. The system according to claim 5, wherein the markers (11) for MR imaging are provided in the predetermined area for attaching the indication device.

MR scanner system with an MR scanner (3) including an MR bore (4) and for aligning a patient within the MR scanner (3) according to any of the preceding claims, wherein

the tabletop (1) and the indication device are configured to be movable inside and outside the MR bore (4), respectively.

8. MR scanner system according to claim 7, wherein positioning electronics is provided for deducing the position of the tabletop (1) relative to the MR bore (4).

9. MR scanner system according to claim 8 wherein the positioning electronics (15) comprises a position encoder, a laser interferometer or/and a machine vision system.

10. Method for generating a visible indication signal for aligning a patient within an MR scanner (3), the method comprising the following steps:

providing a tabletop (1) on which a patient (2) may be supported, providing an indication device for sending out a visible indication signal onto at least a part of the patient's body supported on the tabletop (1), wherein the indication device is part of a frame which is configured for being attached to the tabletop (1) and wherein the frame is part of an RF coil holder (7)

attaching the indication device in a predetermined area of the tabletop (1) in a predetermined position and orientation in a fixed manner, and

sending out the visible indication signal.