Abstract:
A display system compatible with a magnetic resonance imaging (MRI) apparatus disposed in a magnet room for producing video images to a patient in an MRI magnet tunnel, the images having a three-dimensional (3D) effect. An MRI-compatible 3D display includes a display panel configured to generate optical images having 3D content, and RF and electromagnetic interference filtering. A Faraday cage encloses the display panel, and includes an optically transparent window panel having an electrically conductive mesh and a layer of transparent optically isotropic material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a division of application Ser. No. 13/725,339, filed Dec. 21, 2012, which in turn claims priority from U.S. Provisional Application No. 61/582,323, filed Dec. 31, 2011, and from U.S. Provisional Application 61/729457, filed Nov. 23, 2012, the entire contents of which applications are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The use of displays in a Magnetic Resonance Imaging (MRI) equipment environment was first developed in the late 80&#39;s and early 90&#39;s, as described in U.S. Pat. No. 5,412,419, 5,432,544, 5,627,902, and 5,877,732. 
         [0003]    The earliest form of three dimensional (3D) technology first appeared in the movie industry at the end of the 19th century. The principal concept of this technology is to recreate the way humans see depth in real life; through a phenomenon called “binocular fusion”. 3D TVs digitally recreate the perception of binocular fusion to give viewers an immersive viewing experience with pictures that pop off the screen. With the recent release of new 3D TVs to the market, together with readily available 3D movies and other content, it would be advantageous to bring this new technology to patients in the MRI environment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Features and advantages of the disclosure will readily be appreciated by persons skilled in the art from the following detailed description when read in conjunction with the drawing wherein: 
           [0005]      FIG. 1  is a schematic illustration of a 3D LCD monitor setup in an MRI suite. 
           [0006]      FIG. 2  is a diagrammatic cross-sectional view of an exemplary embodiment of a system for 3D display delivery in the MRI. 
           [0007]      FIGS. 3A and 3B  are cross-sectional diagrammatic illustrations of an exemplary embodiment of a 3D display.  FIG. 3B  illustrates features within circle  3 B of  FIG. 3 . 
           [0008]      FIG. 4  is a diagrammatic depiction of a patient viewing a 3D display while lying in an MRI bore. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    In the following detailed description and in the several figures of the drawing, like elements are identified with like reference numerals. The figures are not to scale, and relative feature sizes may be exaggerated for illustrative purposes. 
         [0010]    A 3D TV and the human eye have a lot in common. Since our eyes are spaced slightly apart, the left and right eye sees images from a slightly different perspective. The human brain then combines the two images to create a 3D impression. A 3D TV works the same way. Two images—displayed from slightly different angles—are viewed through 3D glasses and then combined by the brain to construct a 3D image 
         [0011]    The first generation of 3D shutter glasses produced a 3D effect, in part, with technology embedded in the glasses. 3D shutter glasses function just like a camera shutter. A 3D television, in synchronization with the 3D glasses, alternately flashes a 2D image to each eye through a liquid crystal layer embedded within each lens of the glasses. The viewer&#39;s brain then combines the images flashed to each eye to create a 3D effect. However, the use of 3D shutter glasses in an MRI magnet room application is useless due to the electronics and battery existing in the active shutter glasses. 
         [0012]    The next generation FPR (Film Patterned Retarder) 3D relies on technology embedded in the television. FPR 3D glasses use a circular polarized filter to present two images concurrently to each eye. FPR 3D TVs incorporate the FPR technology in which a polarized film is placed on the 3D television screen to effectively split the left and right images into interweaving odd and even lines onscreen, and along with the 3D glasses which use circular polarization filters of opposite sense, separates the left and right images before they are delivered to the brain. This technically halves the original resolution of 3D content to each eye. The images are then combined by the brain to create the 3D impression. The applicant has recognized that this technology is ideal for use in MRI applications. 
         [0013]    An LCD TV can be shielded to block the emission of electromagnetic interference (EMI) inside of the MRI room, to provide an MRI-compatible display. For example, the front active part of the LCD TV may be shielded with a micro conductive mesh or laser aided conductive mesh which is 30 micrometers thick and will not appear when viewed with the naked eye. The entire LCD monitor will then be housed in a shielded Faraday cage, with inputs for power and the video/audio signals (e.g. carried by fiber optics or by Wi-Fi signals). 
         [0014]      FIG. 1  illustrates a typical component layout within the MRI suite. In this exemplary layout, the MRI magnet is disposed in the magnet room, with a patient table for positioning the patient in the bore of the MRI magnet  10 . An MRI-compatible 3D display such as a large MRI-compatible LCD display  100  is positioned on a wall in the magnet room at a position selected to allow the patient in the MRI bore to observe the display, with the aid of a mirror. In this exemplary embodiment, the MRI-compatible 3D display is a display  100  which employs FPR technology to provide a 3D effect when used with an appropriate set of goggles or glasses, with circular polarization filters of opposite sense through which the image generated by the 3D display is viewed. 
         [0015]    The control room includes the Technologist Station  20  for controlling the MRI system. An FPR-compatible video source  22  capable of generating signals to produce the 3D image is placed in the control room, and its signal is converted (e.g. through an HDMI-to-Fiber Optic Converter  24 ) to an optical signal carried on an optical fiber  26 . The video source may be, for example, a DVD player, HDTV receiver, a PC, etc. The optical fiber is passed from the control room into the equipment room and through a waveguide  28  positioned in a penetration panel  30  to the magnet room and to the large MRI-compatible LCD display  100 . Alternatively, in another embodiment, the video source signals may be broadcast using a Wi-Fi broadband network, wherein a Wi-Fi repeater is used to transmit signals (e.g. from an antenna mounted to the magnet room wall). 
         [0016]      FIG. 2  illustrates the patient setup for the system in further detail. The patient wears the circular polarized passive glasses or goggles  40 , with lenses  42  having circular polarization filters of opposite polarization sense for the left and right eye, typically applied by a filter film, and through the use of a reflective mirror  44 , can view the 3D MRI-compatible display (e.g. a shielded 3D LCD TV) located on either end of the MRI bore (tunnel). The patient goggles  40  are configured to be MRI-compatible and fabricated without magnetic materials. Alternatively, the circularly polarized filters can be built into the passive goggles or applied to the mirror  44  into which the patient looks to see the display image. The patient goggles are typically fabricated of a very thin layer of optically clear plastic on which the filters are formed, and, because of the thinness, do not affect substantially the 3D image quality. 
         [0017]    In exemplary embodiments, the display  100  may be a large screen high definition 3D display or TV, utilizing LCD, LED or OLED technology (i.e. a 3D HD TV) and images generated by the display are relayed to the subject via a reflective mirror applied to a rear surface of a substrate formed of optically isotropic material. Alternatively, this could be a front surface mirror. 
         [0018]    In an exemplary embodiment for use in an MRI magnet room, the 3D TV is housed in a non-magnetic Faraday cage to shield EMI. A clear conductive window overlay is specially made for the MRI 3D application utilizing FR technology, where it is optically clear or transparent and does not affect screen polarization. 
         [0019]    The process of making the conductive window for the display in one exemplary embodiment uses a very fine conductive mesh laminated between two layers of optically isotropic glass or plastic material in a way that the edge of the mesh at the window edges is exposed. A conductive adhesive such as silver epoxy is applied to the mesh and window edges. By applying the silver epoxy, all the window edges become shorted to the mesh, increasing a surface area of conductive material in electrical contact with the mesh. With the conductive window assembled in the housing, the edge of the conductive window stays in tight contact with the housing of the display. For the 3D system to operate properly, the base material of any adhesive or other structures used to build the window may not cause interference with the polarization of the TV. Optically isotropic materials are used for the rf (radio frequency) conductive window on the display and the reflective mirror (i.e. materials having the same optical properties in all directions). The mesh may be sandwiched between the two layers of the window because the mesh is very fine and to protect it from damage. 
         [0020]    Another alternative for constructing the fine mesh is to start with a sheet of conductive copper applied to a glass layer, and then etch away most of the copper, leaving only a very fine line in the shape of very fine mesh. The etching may be done by a laser or other etching techniques. 
         [0021]      FIG. 3A  is a diagrammatic cross-sectional view illustrating features of an exemplary embodiment of a 3D flat panel display  100  suitable for use in the magnet room environment of  FIGS. 1 and 2 .  FIG. 3B  illustrates features within circle  3 B of  FIG. 3A . The display is constructed to provide a Faraday cage  110  defined by non-magnetic, electrically conductive materials. The Faraday cage  110  includes a front bezel or cover structure  112  which circumscribes the display panel area  114 , and rear cover  116 . The cover structure  112  may be fabricated of a non-magnetic electrically conductive material such as, by way of example only, brass or aluminum. The rear cover  116  attaches to the back of the cover structure  112 . The Faraday Cage  110  includes an internal mounting frame structure  120  which is positioned between the inside of the front bezel portion  112 A of the cover structure  112  and the rear cover  116 . The rear cover and the internal mounting frame structure are also fabricated of non-magnetic electrically conductive material, such as brass or aluminum. 
         [0022]    The internal mounting frame structure  120  and the cover structure  112  are configured to support the planar display system components, including the LCD/LED/OLED display panel  130 , an LED backlight panel  140  (for an LCD implementation), and a mesh panel assembly  150  to cover the display panel or window area  114 . The display panel may be a flat panel display such as an LCD (liquid crystal display) panel, an LED (light emitting diode) panel, an OLED (organic light emitting diode) panel, or even a plasma panel, for example. In the case of an LCD display panel, the backlight panel  140  is provided behind the display panel  130 . The backlight panel  140  may be omitted for the implementation in which the display panel is OLED. 
         [0023]    The mesh panel assembly  150  in this exemplary embodiment includes planar layers  150 A and  1508  of transparent optically isotropic material, such as a glass, which sandwich a non-magnetic, electrically conductive mesh  150 C. The opening size of the mesh is preferably sufficiently small so as to block RF signals from passing through, yet large enough to allow the optical image rays pass through. An exemplary mesh opening size is on the order of 50 mesh openings per square inch. The mesh may be fabricated from copper, tungsten or alloy thereof, for example. The mesh panel assembly  150  is constructed to be optically isotropic, i.e. with a refractive index not dependent on the polarization and propagation direction of light. If the mesh panel assembly  150  were to be anisotropic, and exhibit birefringence, this could affect the polarized light emitted from the panel  130  and destroy the 3D effect. The panel  150  could also be a single layer of optically isotropic material, on which the mesh is applied or etched. However, to protect the mesh from damage, sandwiching the mesh between two layers can be advantageous. High quality isotropic glass, and plastics such as isotropic acrylic and CR39, may be employed to form the window assembly  150 . 
         [0024]    In this exemplary embodiment, the display panel  130  is spaced from the mesh panel assembly  150  by an elastomeric spacer member  122 . An EMI (electromagnetic interference) gasket  124 A is positioned between adjacent surfaces of the edge of the mesh panel  150  and the inner surface of flange portion  120 A 1  of the internal mounting frame structure  120 . Another EMI gasket  1248  is positioned between adjacent portions of the back edge  1128  of the cover structure  112  and the back flange portion  120 C 1  of the internal mounting frame structure  120 . The EMI gaskets can be fabricated of a springy non-magnetic, electrically conductive material, such as a copper/bronze alloy. 
         [0025]    The edges of the electrically conductive mesh layer  150 C are brought into contact with the adjacent surface of the internal mounting frame structure  120 , e.g. at  120 D, so that the mesh is electrically connected to the internal mounting frame structure  120 . A grounding connection  180  at the rear cover is connected to system ground within the magnet room so that the Faraday cage  110  is grounded. 
         [0026]    A support structure  160  is positioned between a back panel portion  1208  of the internal mounting frame structure  120  and the lower portion of the LED backlight  140 . The support structure  160  is fabricated of a non-magnetic material such as aluminum. The top edge of the LED backlight is secured by a bracket portion  120 A 2  of the frame structure  120 . A circuit board structure  170  is positioned with an upwardly extending board portion  170 A positioned between the display panel  130  and the backlight panel  140 . The board portion can include circuit traces for making electrical contact with the circuit of the display panel, for example. The particular technique for fabricating the display panel  130  and driving it to provide the 3D display images may be conventional. 
         [0027]    An interface module  190  is positioned within the Faraday cage, adjacent the rear cover  116 , and provides a power supply for the 3D flat panel display  100 , and a connection (e.g. fiber optic, broadband Wi-Fi) for the video source signals to be supplied to the 3D flat panel display  100 . 
         [0028]    The 3D flat panel display  100  in this exemplary embodiment employs FPR technology to provide a 3D effect when used with an appropriate set of goggles or glasses, with circular polarization filters of opposite sense through which the image generated by the 3D display is viewed. Alternatively, the display could use left and right linear polarizations to produce the 3D effects, with corresponding left and right linear polarization on the polarized films applied to the goggles worn by the patient. Other display technologies could produce the 3D effect in conjunction with electronics to create the 3D effect on the display itself, without the need for the patient to wear polarized glasses. For example, parallax barrier, glasses-free displays are known, which work by placing an opaque screen door-like barrier over the screen. Each eye views the barrier from a slightly different angle, and therefore sees different sets of pixels behind it. Some manufactures use an LCD barrier that can be turned off to enable 2D viewing. In the case of the parallax barrier, glasses-free display, the patient might directly view the 3D image reflected from the mirror. In all cases, the optical path between the image panel generating the 3D images and the patient&#39;s eyes should not pass through birefringent materials, which may adversely affect the 3D content of the images. 
         [0029]      FIG. 4  diagrammatically illustrates how, in one exemplary embodiment, a patient in an MRI tunnel could view the 3D images generated by the 3D flat panel display  100 . The patient wears the circular polarized passive glasses or goggles, with lenses having circular polarization filters of opposite polarization sense for the left and right eye, typically applied by a filter film, and through the use of a reflective mirror, can view the MRI-compatible display, e.g. a shielded LCD TV, located on either end of the MRI bore (tunnel). The glasses are configured to be MRI-compatible, without magnetic materials. Alternatively, the circularly polarized filters can be built into the passive glasses or applied to the mirror into which the patient looks to see the display image. The patient can see the display while lying down on the MRI bore, using the combination of the polarized films in conjunction with the reflective mirror. 
         [0030]    The reflective mirror  44  in the MRI bore is optically isotropic, i. e. with a refractive index not dependent on the polarization and propagation direction of light. Typically, the reflective surface is placed on a back side of the mirror substrate, to reduce chances of scratching or damaging the reflective surface (as compared to forming the reflective surface on the front face of the mirror substrate). A suitable exemplary plastic for the mirror substrate is acrylic or CR39. For the case in which the reflective surface is placed on the back surface of the mirror substrate, the light path is through the substrate, which in this case should be formed of an optically isotropic plastic material, to avoid affecting the 3D image content of the viewed image. If the reflective surface is placed on the mirror front face, then the light path does not pass through the mirror substrate, and the substrate material should have little effect on the image quality. 
         [0031]    Although the foregoing has been a description and illustration of specific embodiments of the subject matter, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope and spirit of the invention.