Catadioptric medical imaging system for observing the inside wall of a surgical cavity

Abstract

The invention relates to a catadioptric medical imaging system (1), in particular a surgical microscope (2). During surgery, it may be necessary to gain more information about a surgical cavity (6), in particular the type of tissue (29) at the inside walls (4) of the surgical cavity (6). To solve this problem, the catadioptric medical imaging system (1) according to the invention comprises a camera device (8) and a convex catoptric mirror (20) adapted to be inserted into the surgical cavity (6). The catoptric mirror (20) is mounted on an arm (22) and spaced apart from the camera device (8).

Claims

1. A catadioptric medical imaging system (1) for observing an inside wall (4) of a surgical cavity (6), the catadioptric medical imaging system (1) comprising: a camera device (8); a convex catoptric mirror (20) spaced from the camera device (8), wherein the catoptric mirror (20) is adapted to be inserted into the surgical cavity (6); a correction module (46) adapted to correct distortion of the catoptric mirror (20); and an image processor (52), wherein the correction module (46) is a part of the image processor (52).

2. The catadioptric medical imaging system (1) according to claim 1, wherein the catoptric mirror (20) is a fish-eye mirror.

3. The catadioptric medical imaging system (1) according to claim 1, wherein the catoptric mirror (20) includes a marker (74) which differs from immediate surroundings of the marker (74) in at least one of reflectance, fluorescence, and transparency.

4. The catadioptric medical imaging system (1) according to claim 3, wherein the marker (74) reflects and/or emits light outside the visible light spectrum.

5. The catadioptric medical imaging system (1) according to claim 4, further comprising a controller (36) adapted to automatically adjust a field of view (24) of the camera device (8) to the catoptric mirror (20) based on the marker (74).

6. The catadioptric medical imaging system (1) according to claim 1, further comprising a light source (76) carried by the catoptric mirror (20).

7. The catadioptric medical imaging system (1) according to claim 1, further comprising a controller (36) adapted to automatically adjust a field of view (24) of the camera device (8) to the catoptric mirror (20).

8. The catadioptric medical imaging system (1) according to claim 7, wherein the controller (36) is adapted to automatically fill the field of view (24) of the camera device (8) with the catoptric mirror (20).

9. The catadioptric medical imaging system (1) according to claim 1, further comprising an arm (22), wherein the catoptric mirror (20) is mounted to the arm (22).

10. The catadioptric medical imaging system (1) according to claim 1, further comprising a drive system (30) adapted to move the catoptric mirror (20) relative to the camera device (8).

11. The catadioptric medical imaging system (1) according to claim 1, wherein the medical imaging system (1) is a surgical microscope (2).

12. A catadioptric medical imaging system (1) for observing an inside wall (4) of a surgical cavity (6), the catadioptric medical imaging system (1) comprising: a camera device (8); a convex catoptric mirror (20) spaced from the camera device (8), wherein the catoptric mirror (20) is adapted to be inserted into the surgical cavity (6); and a correction module (46) adapted to correct distortion of the catoptric mirror (20), wherein the correction module (46) comprises correction optics (48) arranged between the camera device (8) and the catoptric mirror (20).

13. A method of imaging an inside wall (4) of a surgical cavity (6), comprising the steps of: inserting a convex catoptric mirror (20) into the surgical cavity (6); arranging the catoptric mirror (20) in a field of view (24) of a camera device (8); and correcting distortion of the catoptric mirror (20) in a correction module (46), wherein the correction module (46) is a part of an image processor (52).

Description

BRIEF DESCRIPTION OF THE DRAWING VIEWS

(1) In the drawings,

(2) FIG. 1 shows a schematic representation of the catadioptric medical imaging system according to the invention, and

(3) FIG. 2 shows a schematic rendition of a catoptric mirror which is used in the catadioptric medical imaging system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) First, the design and function of a catadioptric medical imaging system 1, such as a surgical microscope 2 are explained with reference to FIG. 1. The catadioptric medical imaging system 1 is used for observing an inside wall 4 of a surgical cavity 6, such as a surgical cavity in brain surgery, but also for any other kind of surgical cavity.

(5) The catadioptric medical imaging system 1 comprises a camera device 8 which may be located in an optics carrier 10 together with a lens 12, in particular a microscope lens. The catadioptric medical imaging system 1 may also comprise an illumination device 14 which may also be included in the optics carrier 10. A beam splitter 16 may be provided to add light from the illumination device 14 coaxial to an optical axis 18 of the camera device 8 and directed towards the surgical cavity 6. Light directed towards the camera device 8 from the surgical cavity 6 is separated from light from the illumination device 14 by the beam splitter 16.

(6) The camera device 8 may comprise a multispectral camera or a hyperspectral camera. The camera device 8 may comprise more than one single camera, e.g. for stereoscopic imaging. The camera device 8 may be sensitive in at least one of the UV, IR and NIR spectrum. Additionally or alternatively, the camera device 8 may comprise a stereoscopic camera, so that three-dimensional images of the interior of the surgical cavity 6 may be acquired.

(7) The illumination device 14 may provide illumination light in at least one of the visible light spectrum, the UV spectrum, the IR spectrum and the NIR spectrum.

(8) In order to view the inside wall 4 of the surgical cavity 6, a convex catoptric mirror 20 is provided. The catoptric mirror 20 is adapted to be inserted into the surgical cavity 6. For insertion, an arm 22 is provided.

(9) The convex catoptric mirror 20 is arranged in the field of view 24 of the camera device 8, preferably such that the field of view 24 is filled at least almost completely by the catoptric mirror 20.

(10) The catoptric mirror 20 is preferably a fish-eye mirror, which has a diagonal angle of view of at least 120°, preferably of 180°. Even more preferably, the angle of view in at least one of the horizontal and vertical direction of an image recorded by the camera device 8 is at least 120°, preferably 180°. This allows most or all of the surgical cavity 6 to be surveyed if the convex catoptric mirror 20 is at or close to the inside wall 4 in the surgical cavity 6 opposite the camera device 8. The shape of the convex catoptric mirror 20 may, for example, be (hemi-) spherical, parabolic, hyperbolic or ellipsoid. The convex catoptric mirror 20 may have rotational symmetry and may be aligned with the optical axis 18 of the camera device 8, its base 26 which faces away from the camera device 8 being perpendicular to the optical axis 18.

(11) The arm 22 may be configured for manual handling by the surgeon or an assistant by having a handle 28. In order to avoid damage to any tissue 29 in the surgical cavity 6, the arm 22 is flexible in at least one of its longitudinal direction and a direction perpendicular thereto, preferably both. The stiffness of the arm 22 is preferably not higher than the stiffness of the tissue 29 within the surgical cavity 6. A remotely releasable coupling may be provided for releasably attaching the catoptric mirror to the arm.

(12) In another embodiment, the catoptric mirror is deposited by itself in surgical cavity. The base 26 may be provided with an attachment section 27 for attaching it to the tissue 29. This is particularly useful when the catoptric mirror 20 stays with the surgical cavity 6 without an arm 22. The attachment section 27 may comprise a means for establishing at least one of a chemical and a mechanical connection with the tissue 29, e.g. a glue and/or spikes or hooks.

(13) Preferably, however, the catoptric mirror 20 is and/or may be adapted to be releasably attached to a drive system 30. The drive system 30 is adapted to move the catoptric mirror 20 relative to the camera device 8, preferably in all three spatial dimensions, as indicated by arrows 32. The drive system 30 may be fixed relative to a support frame 34 of the catadioptric medical imaging system 1, which support frame is only indicated schematically. The support frame 34 is preferably stationary with respect to the surgical cavity 6. The optics carrier 10 may be movable with respect to the support frame 34, e.g. by being attached to a pivotable cantilevered boom which supports the optics carrier 10.

(14) The catadioptric medical imaging system 1 may be provided with a controller 36 for controlling the drive system 30, e.g. in response to manipulators 37 of the catadioptric medical imaging system 1, which manipulators 37 are operated by the surgeon. This enables the catoptric mirror 20 to be moved within the surgical cavity 6 and thus allows surgical cavities with complex interior shapes, such as undercuts, to be surveyed.

(15) In operation, the camera device 8 will output image data 38, e.g. as a time series 40 of frames 42, each frame 42 consisting of a plurality of pixels 44.

(16) Due to the shape of the convex catoptric mirror 20, the images gathered from the catoptric mirror 20 as represented by or in the frames 42 will be distorted. This distortion may impede visual analysis of the frames 42 by a surgeon or assistant.

(17) To correct or at least reduce distortion caused by the catoptric mirror 20, a correction module 46 may be provided. The correction module 46 may comprise correction optics 48 which are preferably arranged between the surgical cavity 6 and the camera device 8. Preferably, the correction optics 48 can be quickly mounted and unmounted, e.g. be moved into the field of view 24 of the camera device 8. For example, a support 50 for pivoting the correction optics 48 in front of the camera device 8, in particular the lens 12, and back may be provided.

(18) The catadioptric medical imaging system 1 may further comprise an image processor 52, which may also comprise the correction module 46 or a part thereof, which in this case may be implemented as software or electronic hardware. The correction module 46 of the image processor 52 is adapted to correct distortion of the convex catoptric mirror 20 in the image data 38. For example, the image processor 52 may be adapted to compute distortion-free three-dimensional images from stereoscopic images of the catoptric mirror 20. The image distortion correction performed by the image processor 52 may be used together with the correction optics 48 to obtain optimum results.

(19) The catadioptric medical imaging system 1 may further comprise at least one display 54, which may be integrated into the optics carrier 10. The display 54 is coupled to the image processor 52 and adapted to display output image data 56 which have been derived from the image data 38. For example, the output image data 56 may comprise an output frame 58 based on at least one distortion-corrected frame 42. The display 54 may only show a part 60 of the output frame 58. The part 60 may be moved in the output frame 58 depending on the operation of manipulators 62 of the catadioptric medical imaging system 1.

(20) Movement of the part 60 within the output frame 58 may also be effected by including a virtual reality system in the catadioptric medical imaging system 1, such as movement-sensitive goggles as a display 54.

(21) FIG. 2 shows an exemplary embodiment of the convex catoptric mirror 20 and the arm 22. The convex catoptric mirror 20 is shown only for explanatory purposes as having a hemispherical mirror surface 70. Any other shape which allows the interior of the surgical cavity to be surveyed may be used. The base 26 of the catoptric mirror 20 is shown to be circular, but can also be of any shape, e.g. polygonal, such as rectangular, as indicated by phantom lines 72. The rectangular base 72 may be adapted to correspond, in its proportions, to the side ratio of a frame 42 as recorded by the camera device 8. A rectangular base 72 allows the field of view 24 to be completely filled by the catoptric mirror 20.

(22) The catoptric mirror 20 may be provided with at least one marker 74 having a fluorescence, reflectance and/or transmissivity which differs from its immediate surroundings. For example, the marker 74 may have an increased or reduced reflectance in a non-visible part of the light spectrum, such as UV, IR or NIR, or in one or more wavelengths of the visible-light spectrum. The marker 74 may, additionally or alternatively, be fluorescent. The marker 74 may be used to adjust the position of the catoptric mirror 20 relative to the optical axis 18 of the camera device 8, either manually or using the drive system 30. A plurality of markers 74 can be arranged around the optical axis 18. The marker 74 may also be or include a light source, such as an LED.

(23) In another embodiment, the catoptric mirror 20 may be at least sectionally transparent or semi-transparent to allow light to pass from the interior of the catoptric mirror 20 to the outside. In particular, transparency at a marker 74 may be different to transparency of the immediate surrounding of the marker 74. Thus, the light passing through the markers 74 allows said markers 74 to be recognized and identified automatically.

(24) A light source 76 may be arranged inside the catoptric mirror 20. The light source 76 may emit illumination light in at least one of the visible light spectrum, the UV spectrum, the IR spectrum and the NIR spectrum. The light from the light source 76 may be used to trigger fluorescence in the inside walls 4 of the surgical cavity 6 if at least one fluorophore 78 (FIG. 1) is injected into the tissue 29 bordering the surgical cavity 6. The catadioptric medical imaging system 1 may be provided with a band-stop filter (not shown) for blocking light from the light source 76.

(25) The light source 76 may e.g. comprise at least one (or more) LED(s) 82. The catoptric mirror 20 may include a power source 84 for driving the light source 76 and e.g. a communication module 86 for wired or wireless connection to e.g. the controller 36 of the catadioptric medical imaging system 1. The light source 76 may also be powered through a power line which extends through the arm 22.

(26) The arm 22 may be telescopic, as exemplarily shown in FIG. 2. The extension or collapse of the arm 22 may be driven by the drive system 30.

(27) The arm 22 may be provided at its end with a coupling 87 for releasably engaging with the catoptric mirror 20 e.g. by being provided at its end with a suction cap for engaging the mirror surface 70 using a vacuum. The coupling 87 may be used for depositing and picking up the catoptric mirror 20.

(28) Instead of or additionally to forming the arm 22 from flexible material, one or more joints 88 may be provided between the catoptric mirror 20 and the handle 28 (if present) or the drive system 30. The joint 88 is preferably adapted to provide flexibility to the arm 22. Again, the flexibility of the arm should be higher than the compressibility of the tissue 29 to prevent tissue damage. The joint 88 is preferably flexible and thus may exert a restoring force if deflected.

(29) A flexion sensor 90 may be provided, which is preferably connected to the controller 36. The flexion sensor 90 is adapted to output a flexion signal which is representative of an amount of flexion in the joint 88 or of the arm 22 as a whole. The controller 36 may be adapted to stop or revert any motion of the drive system 30 if the flexion as represented by the flexion signal exceeds a predetermined amount. Additionally or alternatively, an alarm signal may be triggered by the flexion signal if the amount of flexion of the arm 22 is too high. For example, the arm 22 may be provided with a buzzer and/or an LED (not shown) for outputting the alarm signal depending on the flexion signal.

(30) If the mirror 20 is to be attached to the tissue 29, it should be light weight. In such a configuration, the catoptric mirror 22 may be hollow or filled with a lightweight material such as foam. The mirror surface 70 may be formed by a foil.

REFERENCE NUMERALS

(31) 1 catadioptric medical imaging system 2 surgical microscope 4 inside wall of surgical cavity 6 surgical cavity 8 camera device 10 optics carrier 12 lens, in particular microscope lens 14 illumination device 16 beam splitter 18 optical axis 20 convex catoptric mirror 22 arm 24 field of view of camera device 26 base of convex catoptric mirror 27 attachment section 28 handle 29 tissue of the surgical cavity 30 drive system 32 arrows 34 support frame of catadioptric medical imaging system or microscope 36 controller 37 manipulator 38 image data 40 times series 42 frame 44 pixel 46 correction module 48 correction optics 50 support for correction optics 52 image processor 54 display 56 output image data 58 output frame 60 displayed part of output frame 62 manipulator 70 mirror surface 72 phantom line 74 marker 76 light source 78 fluorophore 82 LED 84 power source 86 communication module 87 coupling 88 joint 90 flexion sensor