The invention relates to an arrangement for image formation and image transmission
for magnetic resonance tomographs
(MRT) according to the genus
of the claims.
Magnetic resonance tomography, in which a patient to be examined,
whose head is in a head coil into a tunnel of a
Tomographs has become one in the last decade
developed a major medical examination method. It will be
the patient one or two eyed images or video sequences presented
and thereby his brain in defined states. The pictures
generating unit must because of their electromagnetic energy to be ensured
to the MRI itself generally outside
of the MRI tunnel so that the images of the imaging unit
in the narrow tunnel to the patient's eyes must be transferred. In addition to
are often used simultaneously with the functional MRI measurement response times and
Error rates of the patient recorded. Especially enlightening
thereby the evaluation of the pupil movement and the eyelid strike of the
Patients undergoing a transmission
on an outside
the MRT tunnel receiving device and thus more
Claim space in the tunnel.
In detail, from WO 95/14429 a fiber optic transmission and
Projection system with a translucent lens for aperture widening and
a subsequent one
Mirror eyepiece on the patient side known, where the mirror
serves to compensate for visual defects of the patient. The disadvantages
of this system are in the limited image resolution through the fiber optics,
the high price for
fiber optic image guide with ordered fibers and in the acute
Risk of fiber breakage
to see in the picture ladder. The company Avotec Inc. offers in their publication "Eye Tracking" from 23.06.03 additionally
Fiber optic image guidance system for observation of the pupil movements of a
Patients. The one for this
Image guides are connected to the mirror eyepiece.
The EP 12 05 145 A2
has a screened video projection system containing a video projector and a lens group on the head coil near the patient's eyes. An image of the projector projected onto the lens and viewed by a patient. The main disadvantage of the system is the small viewing distance of nominally 250 mm. Although this can be slightly increased by moving the mirror group, however, the patient must accommodate at least +2 d, which is not possible in particular in older patients without glasses. Glasses may not be worn on MRI. Another disadvantage of the system is the large change in the visual angle with a variation of the visual distance; in contrast, the experimental paradigms often require adherence to defined visual angles.
In the US 5076275 A
and US 5864331 A
MRI systems are described in which a patient looks over deflecting means at an image which is produced on a projection screen outside the MRT tunnel. The disadvantage here is the highly restricted by the MRI tunnel field of view and the lack of compensation for any existing defective vision. In addition, these MRI systems do not allow the display of independent, eg stereoscopic images separately for each eye.
In the US 5339813 A
describes a viewing system for MRI tunnels in which a patient looks through a telescope directly at the display of a video projector whose front lens is removed. Such a viewing system has extremely small exit pupils; his eyepieces must be aligned exactly with the patient's pupils. Even with relatively small eyesight of the patient in the direction of one of the edges of the image, the images can wander out of the field of vision.
In the US 5134373 A
For example, an imaging channel with a fiber optic image guide and a prism is described in which an image is projected onto a screen for viewing by a patient. The MR Eyetracker from Cambridge Research Systems Ltd., company brochure dated 15.07.03 also works with fiber optic cables. For the purpose of functional magnetic resonance imaging, a pupil movement tracking device comprises optical fibers and a deflection mirror that permits combination with a video and audio system. The disadvantage of this eye tracker is that there is no image transfer from a patient's eye to a camera, but only scattered light components of a pupil reflex are evaluated via two light guides. In addition, a calibration of the Eyetracker of approximately 5 minutes is required for each patient before use.
The US 5877732 A
discloses a three-dimensional high-resolution video and audio system based on magnetic resonance images in which an optical relay lens system is used to generate an image to be viewed by a patient. A simultaneous detection of the eye condition during the image viewing does not take place.
It is an object of the present invention to provide a compact, stable, inexpensive yet accurate image transfer system in an MRI. The system should be in easier For example, image transfer from one or more imagers outside of an MRI tunnel to the eyes of a patient in the MRI tunnel and simultaneous image transfer of the patient's eyes to at least one camera outside the MRI tunnel.
According to the invention
This object is achieved by the characterizing features of the first claim
Advantageous embodiments of the invention are specified in the subclaims.
The image transfer
increased with the help of an endoscope
the use of fiber optic cables not just the economy
and security of image transmission,
but also their dissolution. Advantageous
can use the same endoscope for image transmission
paradigms on both the patient's eye and imaging
of the patient's eye to a camera outside the MRI tunnel. Furthermore
The use of an endoscope has the advantage of being targeted
optical system aberrations of the entire image transmission system
or its enlargement in
can be easily corrected. By use
two endoscopes or image transmission systems
Is it possible,
to each eye and from each eye an independent, stereoscopic image
to create. The means for image correction can also be applied to the endoscopes.
or be subordinate. Every endoscopic system is to be switched off
from foreign influences
arranged in a closed imaging channel. For lighting
Of the eye, IR light is preferably used, which passes through the eye
at least one optical fiber outside
the image transmission system or
through the image transmission system
is forwarded. Both possibilities
to the illumination of the eye can
also be combined with each other. As infrared light sources may preferably
LED s serve. So that the image of the eye the imaging surface of the
Camera is fully exploited, it is an imaging optical link immediately
Invention will be explained in more detail below with reference to the schematic drawing. It
1 an embodiment of the invention in an MRI,
2 a detailed optical structure of an inventive arrangement and
3 one of 2 deviating optical design of the optical arrangement in the vicinity of the patient's eye.
In 1 is located in a tunnel 11 a magnetic resonance tomograph 10 a couch 12 with a patient 14 , an image transmission system, in a closed imaging channel 13 is arranged, and a head coil 15 for the patient's head 14 , The picture channel 13 connects to a shielded housing 16 on, with or on a stand 33 is pivotally mounted in a plane that in 1 directed at right angles to the plane of the drawing. In addition, the housing 16 and the picture channel 13 with or on the stand 33 adjustable in height, parallel to the drawing plane, and the imaging channel 13 is in terms of its length, eg. By a telescopic design, changeable.
Before the patient 14 on the couch 12 in the MRT tunnel 11 is driven, the image transmission system must by appropriate changes of the imaging channel 13 over the patient 14 be positioned so that the patient is in the eyepiece ( 29 in 2 ) can look. Ametropia of the patient 14 between approx. +6 dpt and -6 dpt can be compensated for example by adjusting the eyepiece. Due to the formation of the eyepiece, the patient can fully see the image information regardless of his pupil distance without individual adaptation of the insights into the image transmission systems. In the exemplary embodiment, the exit pupil of the image transmission system is approximately 20 mm in front of the front lens of the eyepiece and has a diameter of 20 mm.
It goes without saying that for double-blind consideration for each
Eye an image transmission system
must be present.
In 2 are housed in an electromagnetic radiation shielding housing 16 the belonging to an image transmission system electrical or electronic components. To the case 16 closes a substantially formed as a tube imaging channel 13 with an optical axis OO, which consists of a magnetically and electrically non-conductive material. The pipe 13 protrudes into the housing with one end 16 into and near this end and in the case 16 an approach 46 on, in which a camera 32 and an optic 45 are located. At the other end is the tube 13 Doubly cranked, so that the visualized by the optical axis OO optical imaging beam path of the image transmission system undergoes a parallel displacement and to an eye 44 is directed. From the case 16 are seen in the tube 13 one light source in succession 18 , a condenser 19 , a display 17 , an IR-selective mirror 20 , a multiple array of lenses 24 and 25 , which in their entirety form an endoscopic imaging system and repeats intermediate pictures 26 produce. The last lens 25 is already in the bent part 22 of the pipe 13 , between two deflection mirrors that provide the optical offset 27 . 28 (or prisms). The deflection mirror 28 are a lens group 30 for optical correction, a partially transparent mirror 31 and a diffuser 23 downstream. Furthermore, are in the cranked part 22 of the pipe 13 a concave mirror 35 , an edge filter 37 and an eyepiece 29 for an eye about 20 mm away 44 , The illumination of the eye 44 serve an IR light source 33 in the shielded housing 16 and a fiber optic cable 34 that is essentially parallel to the pipe 13 close to the eye 44 is guided. The IR light source 33 can also be in the pipe 13 are located and the lighting of the eye 44 done through the pipe.
the display 17 becomes from the visible light emitting light source 18 over the condenser 19 illuminated. Through the mirror 20 (or prism cube with splitter surface), the endoscopic imaging system n ( 24 . 25 ), the lens group 30 and about the deflection mirrors 27 . 28 . 31 becomes the display 17 on the reflected light disc 23 displayed. About the variation of the number of lens groups 24 . 25 In the endoscopic imaging system, the image transmission system can basically be adapted to the tunnel length. In a telescopic design of the imaging channel 13 The length change must be in one of the parallel beam paths between two lenses 24 and 25 done by the endoscopic system. Through the eyepiece 29 and the non-imageable partially transmissive mirror in this case 31 looks at the patient's eye 44 the picture of the display 17 on the incident light disc 23 , which can be designed to compensate for a possible caused by the eyepiece field curvature corresponding curved. A possibly still existing distortion of the Okularabbildung can by an opposite distortion of the Okularbildes on the spreading disc 23 be compensated. This can also serve a targeted optical distortion of the endoscopic beam path; in 2 is the targeted optical distortion by the lens group 30 reached.
The eye 44 is illuminated with IR light and through the eyepiece 29 as well as the concave mirror 35 an intermediate picture 36 of the eye in the bent part 22 generated. The location of this intermediate image is determined by a corresponding focal length of the concave mirror 35 chosen so that this intermediate image through the splitter mirror 31 through and from the endoscopic imaging system n. 24 . 25 ) and by reflection at the IR-selective mirror 20 to the camera 32 transmitted and imaged with infrared light.
Thus the normally white light from the display 17 from the concave mirror 35 is not reflected back, this must be IR-selective or it will, as in 2 shown an IR edge filter 37 arranged in the beam path. When tilting the filter 37 There are no disturbing reflections from the filter surface. In front of the camera 32 is advantageously the optical member 45 attached, which is the IR image of the patient's eye 44 projected in optimal size on the image pickup surface.
Will the eyepiece 29 shifted along its optical axis to compensate for defective vision of the patient, so shifts the intermediate image 36 of the patient's eye 44 so slightly axial that the image of the patient's eye on the camera 32 stays sufficiently sharp.
In 3 is the in 2 Twofold cranked part 22 of the picture channel 13 through a simple right-angled bend 47 replaced. Incidentally, in the picture channel 13 again the intermediate image level 26 and the endoscope lenses 24 and 25 recognizable, between which a telecentric beam path exists. The endoscopic system 24 . 25 forms an unillustrated display (paradigms) via an IR-transmissive deflection mirror 38 and a lens group 30 on a diffuser 40 from. This display image is through the eyepiece 29 and the IR-selective mirror 39 viewable.
The lighting of an in 3 Patient eye not shown is used by an unillustrated IR LED outgoing light guide cable 24 , For IR imaging of the eye in an intermediate image plane 36 becomes the eyepiece 29 together with a lens 41 used, wherein the deflection of the imaging beam path through the IR-selective mirror 39 and the deflecting mirror 42 he follows. The deflection mirror 43 leads the IR imaging beam path back to the endoscopic imaging system, whose focus facing the eye in the intermediate image plane 36 located. For the rest, this is true too 2 Said analogously.
- Magnetic resonance tomograph
- Figure channel
- head coil
- light source
- intermediate images
28, 38, 42, 43
- Deflecting mirror (prisms)
- lens group
- optical cable
- concave mirror
- Intermediate image (plane)
- cut-off filter
- By light diffuser
- patient's eye
- IR light source