MONITORING SYSTEM WITH A CAMERA AND NON-METALLIC MIRROR FOR MAGNETIC RESONANCE EXAMINATION SYSTEM

Abstract

A magnetic resonance examination system with an examination zone (11) and comprising a camera (21) and non-metallic mirror (22), in particular within the examination zone (11), arranging an optical pathway (23) between a portion of the examination zone (11), via the non-metallic mirror (22), and the camera (21). The camera can obtain image information from that portion even if the direct line of sight (28) is blocked. The non-metallic mirror is a dielectric mirror having a macroscopically grated base.

Claims

1. A magnetic resonance examination system with an examination zone, the system comprising: a monitoring system that comprises a camera and a non-metallic mirror, within the examination zone, arranging an optical pathway between a portion of the examination zone, via the non-metallic mirror, and the camera, wherein the non-metallic mirror is a dielectric mirror having a macroscopically grated base wherein the macroscopically grated base comprises a plurality of patches that are tilted relative to the normal to the planar extension of the base such that the orientations of the individual patches determine an effective tilt to the angle of reflection for light from and/or to the examination zone.

2. The magnetic resonance examination system of claim 1, wherein said monitoring system is adapted to obtain information from the patient, based on an image output of said camera, wherein said information includes at least one of: vital signs of the patient, movement of the body of the patient, an indication of distress or of a mood of the patient, a respiratory cycle phase, or a cardiac cycle phase.

3. The magnetic resonance examination system of claim 1, wherein the optical pathway circumvents auxiliary equipment that is placed in the examination zone.

4. The magnetic resonance examination system of claim 1, wherein the non-metallic mirror is a dielectric mirror having a macroscopically grated base, onto which a stack of dielectric layers is deposited, such that a tilted effective reflection from the layered stack is obtained.

5. The magnetic resonance examination system of claim 1, wherein said patches are each at an equal oblique angle to the normal of the lateral extension of the base.

6. The magnetic resonance examination system of claim 1, wherein said non-metallic mirror is adjustably mounted so that its orientation to the inner wall can be varied.

7. The magnetic resonance examination system of claim 1, including a light source for directing a light beam via the non-metallic mirror into the examination zone.

8. The magnetic resonance examination system of claim 1, wherein the monitoring system includes a plurality of non-metallic mirrors.

9. The magnetic resonance examination system of claim 1, wherein the camera is sensitive for infrared radiation and the non-metallic mirror or mirrors are reflective for infrared radiation.

10. The magnetic resonance examination system of claim 1, wherein the non-metallic mirror is transparent in the visual wavelength range.

11. A monitoring system to view the examination zone of a magnetic resonance examination system by way of a camera, the monitoring system comprising a camera and a non-metallic mirror for placing in said examination zone so as to arrange an optical pathway between a portion of the examination zone, via the non-metallic mirror, and the camera, wherein the non-metallic mirror is a dielectric mirror having a macroscopically grated base, wherein the macroscopically grated base comprises a plurality of patches that are tilted relative to the normal to the planar extension of the base such that the orientations of the individual patches determine an effective tilt to the angle of reflection for light from and/or to the examination zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 shows a schematic side-elevation of an example of the magnetic resonance examination system incorporating the invention;

[0027] FIG. 2 shows a schematic side-elevation of another example of the magnetic resonance examination system incorporating the invention and

[0028] FIG. 3 shows a detail of an example of the non-metallic mirror incorporated in the monitoring system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] FIG. 1 shows a schematic side-elevation of an example of the magnetic resonance examination system incorporating the invention. The magnetic resonance examination system comprises a main magnet structure 10, which defines the examination zone. A patient to be examined 13 may be positioned on a patient carrier 14, e.g. a patient couch, into the examination zone. The main magnet structure includes a frame holding magnet windings to generate a stationary uniform magnetic field in the examination zone. The examination zone may be a cylindrical volume encompassed by a set of coaxial (super conductive) windings. The acquired magnetic resonance signals are applied to a reconstructor 15 which reconstructs magnetic resonance image(s) from the magnetic resonance signals. The reconstructed magnetic resonance images are finally output 16 for viewing, processing or storage. Auxiliary equipment, such as the RF T/R head coil 12 is placed in the examination zone, notably to acquire magnetic resonance signals from the patient's 13 head. For example, brain, cranial and/or cervical scans may be typically performed with the aid of such head coil, which may (at least to a large extent) fully enclose the head and neck of the patient, such that a direct view by the camera is mostly obscured.

[0030] The monitoring system 20 functions to obtain information from the patient to be examined, notably on vital signs and on motion. Notably, respiratory motion and cardiac motion may be derived from image information of outer hull of the patient's body. The camera 21 may be mounted close to one entry of the examination zone. For example, the camera may be integrated in, on mounted on, a flange of the MR bore (e.g. such that the usable free bore diameter is not affected or only minimally reduced, and/or to avoid or minimize interference with the operation of the MR system).

[0031] A camera control 25 is provided to control the camera 21, notably as to the direction into which the camera's range extends into the examination zone as to the focus length of the camera. Images of the inside of the examination zone 11 acquired by the camera 21 may be shown on a display 26. In this way, staff or an operator may visually monitor the patient to be examined in the examination zone. The image information acquired by the camera 21 may also be applied to a motion detector 27 (which may for example be implemented in software) to derive physiological information as respiratory and/or cardiac cycle phase of the patient to be examined from the image information acquired by the camera 21. The respiratory and/or cardiac phase information may be applied to the reconstructor 15 to correct the acquired magnetic resonance signals for motion and/or apply motion corrections to the reconstructed magnetic resonance images.

[0032] The monitoring system 20 further includes the non-metallic mirror 22 that may be mounted to the examination zone's inner wall 17 (e.g. the inner wall of the magnet bore enclosure). The monitoring system may comprise a pivot 24 to mount the non-metallic mirror such that its orientation can be controlled by the adjustable pivot. The non-metallic mirror 22 may be directly mounted to the inner wall 17 so that only little space in the examination zone is taken up by the non-metallic mirror. The non-metallic mirror generates (additional) optical paths 23 from a portion of the patient to be examined to the camera. Such an additional optical path 23 via the camera may circumvent obstructions, such as the RF T/R head coil 12 shown in FIGS. 1 and 2 as an example. Accordingly, the non-metallic mirror achieves that potions of the patient to be examined may be monitored, even if the camera's direct line of sight 28 is obstructed e.g. by the RF T/R head coil 12.

[0033] Alternatively, (or additionally) the non-metallic mirror may be mounted on, or formed as part of, a head T/R coil, e.g. as used for cervical, cranial and/or neuroradiological MR examinations. It is to be noted that integrating the mirror in or on the head coil may avoid costly or complex modification of existing equipment, e.g. of the scanner bore. While a relatively far distance between the camera, e.g. mounted on a flange of the bore, may result in a very limited field of view, e.g. only showing the forehead or part thereof, this may be sufficient for some applications, e.g. to monitor blood pulsation by slight variations in pixel intensity.

[0034] FIG. 2 shows a schematic side-elevation of another example of the magnetic resonance examination system incorporating the invention. The monitoring system of the magnetic resonance examination system shown in FIG. 2 is similar to that shown in FIG. 1. The monitoring system of FIG. 2 is additionally provided with an illumination system to illuminate (part of) the examination zone. The illumination system includes a light source 29, e.g. an infrared (IR) light source. For example, the light source may be located side-by-side with the camera 21. The light source may be located at a distance from the camera, but, for example, in generally the vicinity thereof. The light source(s) may thus illuminate a relevant part of the examination zone, for example directly and/or via the non-metallic mirror 22. In this way, parts of the examination zone that may be obstructed can be illuminated via the non-metallic mirror. Hence, the non-metallic mirror may achieve that the illumination of the examination zone is effective in spite of the presence of potentially blocking objects in the examination zone. FIG. 3 shows a detail of an example of the non-metallic mirror 22 incorporated in the monitoring system. The non-metallic mirror 22 comprises a base plate 31 with a macroscopically grated base 33 on one side of the base plate 31. The macroscopically grated base 31 has a plurality of patches 34 that are tilted relative to the normal 35 to the base plate's planar extension. That is the patches each are at an angle θ.sub.g to the normal 35 to the base plate's planar extension. The lateral dimension of individual patches is substantially larger than the wavelength of the (IR) light from the examination zone. Thus, the patches induce an effective tilt to the angle of reflection for light form/to the examination zone. This effective tilt can be determined by the orientations of the individual patches.