MEDICAL IMAGING SYSTEM, DEFLECTION UNIT AND METHOD FOR CALIBRATING A MEDICAL IMAGING SYSTEM

Abstract

The present invention relates to a medical imaging system (1) for imaging an object, comprising an imaging unit (10) comprising at least one imaging device (11) and a deflection unit (20) comprising at least one imaging deflection member (21a), wherein the at least one imaging deflection member (21a) is configured to be selectively disposed in an optical path of the imaging device (11) to selectively deflect an imaging beam.

Claims

1. Medical imaging system (1) for imaging an object, comprising: an imaging unit (10) comprising at least one imaging device (11) and a deflection unit (20) comprising at least one imaging deflection member (21a), wherein the at least one imaging deflection member (21a) is configured to be selectively disposed in an optical path of the imaging device (11) to selectively deflect an imaging beam.

2. Medical imaging system (1) according to claim 1, wherein the deflection unit (20) is at least partially releasably attachable to an imaging side of the imaging unit (10).

3. Medical imaging system (1) according to claim 2, wherein the deflection unit (20) comprises at least one attachment member (24), preferably configured as a snap-fit member, attachable to a corresponding receiving portion of the imaging unit (10).

4. Medical imaging system (1) according to claim 1, wherein the deflection unit (20) comprises at least one locking member (25) to lock a connection of the deflection unit (20) and the imaging unit (10).

5. Medical imaging system (1) according to claim 1, wherein the medical imaging system (1) further comprises a cover (40) releasably attachable to a side of the deflection unit (20) to be opposed to the imaging side of the imaging unit (10).

6. Medical imaging device (1) according to claim 1, wherein the medical imaging system (1) further comprises at least one light source (12, 13) separate from the imaging device (11), and wherein a light emitted from the at least one light source is deflectable by the at least one imaging deflection member (21a) and/or at least one separate light deflection member (22a, 23a) of the deflection unit (20).

7. Medical imaging system (1) according to claim 1, wherein the medical imaging system (1) further comprises a control unit (14) to adjust a deflection angle of the at least one imaging deflection member (21a.

8. Deflection unit (20) for a medical imaging system (1) according to claim 1, wherein the at least one imaging deflection member (21a) is a deflection mirror or a deflection prism.

9. Deflection unit (20) according to claim 8, wherein the at least one imaging deflection member (21a) is a wavelength-selective deflection member.

10. Deflection unit (20) according to claim 8, wherein a deflection angle and/or the wavelength-selectivity of the at least one imaging deflection member (21a) are/is configured to be adjustable.

11. Deflection unit (20) according to claim 10, wherein the medical imaging system (1) further comprises at least one light source (12, 13) separate from the imaging device (11), and wherein a light emitted from the at least one light source is deflectable by the at least one imaging deflection member (21a) and/or at least one separate light deflection member (22a, 23a) of the deflection unit (20), wherein the at least one separate light deflection member (22a, 23a) is a deflection mirror or a deflection prism, wherein the at least one separate light deflection member (22a, 23a) is a wavelength-selective deflection member, wherein a deflection angle and/or the wavelength-selectivity of the at least one separate light deflection member (22a, 23a) are/is configured to be adjustable, and wherein a deflection angle and/or the wavelength-selectivity of the at least one imaging deflection member (21a) and the at least one separate light deflection member (22a, 23a) are configured to be adjustable independently from each other.

12. Deflection unit (20) according to claim 8, wherein the deflection unit (20) provides spatially separated ducts (21, 22, 23) for the at least one imaging deflection member (21a).

13. Method for calibrating a medical imaging system (1), comprising the steps of: defining a region of interest (ROI) as initial tool center point, positioning an imaging focus of an imaging unit (10) in a first position corresponding to the region of interest (ROI), recording a first image in the first position by the imaging unit (10), rotating the imaging unit (10) around the region of interest (ROI) in a second position with the region of interest (ROI) defining the center of rotation, recording a second image in the second position by the imaging unit (10), comparing the first and second image to identify a deviation, and setting the initial tool center point as calibrated tool center point, when the identified deviation is below a predetermined threshold, or recalculating a calibrated tool center point based on the identified deviation, when the identified deviation is equal to or above a predetermined threshold.

14. Method according to claim 13, wherein the calibrated tool center point is set as tool center point for the imaging system (1) or wherein the imaging system (1) is adjusted such that the initial tool center point complies with the calibrated tool center point.

15. Method according to claim 13, wherein the region of interest (ROI) comprises at least one predetermined artefact to identify a deviation when comparing the first image with the second image.

16. Medical imaging system (1) according to claim 6, wherein the medical imaging system (1) further comprises a control unit (14) to adjust a deflection angle of the at least one separate light deflection member (22a, 23a).

17. Deflection unit (20) for a medical imaging system (1) according to claim 6, wherein the at least one separate light deflection member (22a, 23a) is a deflection mirror or a deflection prism.

18. Deflection unit (20) according to claim 17, wherein the at least one separate light deflection member (22a, 23a) is a wavelength-selective deflection member.

19. Deflection unit (20) according to claim 17, wherein a deflection angle and/or the wavelength-selectivity of the at least one separate light deflection member (22a, 23a) are/is configured to be adjustable.

20. Deflection unit (20) according to claim 17, wherein the deflection unit (20) provides spatially separated ducts (21, 22, 23) for the at least one separate light deflection member (22a, 23a).

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0056] FIG. 1 is a schematic cross-sectional view of an imaging system according to an exemplary embodiment;

[0057] FIG. 2 is a schematic perspective top view of an exemplary deflection unit applicable to the exemplary embodiment of the imaging system according to FIG. 1;

[0058] FIG. 3 is a schematic side view of the exemplary deflection unit according to FIG. 2;

[0059] FIG. 4A is a schematic representation of an imaging unit of the imaging system according to FIG. 1 in a first position and in a second position according to an exemplary embodiment of a method for calibrating a medical imaging system with an initial tool center point corresponding to a calibrated tool center point; and

[0060] FIG. 4B is a schematic representation of an imaging unit of the imaging system according to FIG. 1 in the first position and in the second position according to the exemplary embodiment of a method for calibrating a medical imaging system with the initial tool center point deviating from a calibrated tool center point.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0061] FIG. 1 shows a schematic cross-sectional view of an imaging system 1 according to an exemplary embodiment. The imaging system 1 comprises an imaging unit 10 and a deflection unit 20 releasable attachable to the imaging unit 10. The imaging unit 10 comprises an imaging device 11, a first light source 12 and a second light source 13. The inlet of the imaging device 11 for receiving an image is arranged on an imaging side of the imaging unit 10. The outlets of the first light source 12 and the second light source 13 to emit light are also arranged on the imaging side of the imaging unit 10. In FIG. 1, the optical path of the imaging device 11 and the light paths emitted by the first light source 12 and the second light source 13 extend from the imaging side of the imaging unit 10 perpendicular to the imaging side in a direction away from the imaging unit 10 as indicated by the solid arrows. Further, the imaging unit 10 incorporates a control unit 14. In alternative embodiments, the control unit may be incorporated in the deflection unit or an external control device. The control unit 14 is configured to independently control the emitting angle of the light of the first light source 12 and second light source 13 as well as the receiving angle of the optical path for receiving an image of the imaging device 11. In alternative embodiments, the control unit 14 may only control one of the respective angles or a specific combination thereof. The control of the respective angles allow an adjustment of a deflection by the deflection unit 20, as described later.

[0062] The deflection unit 20 comprises an imaging duct 21 with an imaging deflection member 21a, a first light duct 22 with a first light deflection member 22a, and a second light duct 23 with a second light deflection member 23a. The ducts 21, 22, 23 are spatially separated from each other to isolate the optical path of the imaging device 11, the light emitted from the first light source 12 and the light emitted from the second light source 13 from each other. In other words, the deflection unit 20 provides three separated channels each extending spatially separated through the deflection unit 20. Further, the deflection unit 20 is configured such that each opening of a respective duct 21, 22, 23 on an attachment side of the deflection unit 20 facing the imaging side of the imaging unit 10 complies with the inlet of the optical path of the imaging device 11 and the outlet of the light emitted from the first light source 12 and second light source 13, respectively. Specifically, the opening of the first light duct 22 on the attachment side of the deflection unit 20 surrounds the emitting area of the first light source 12, the respective opening of the imaging duct 21 surrounds the optical path to be received by the imaging device 11, and the respective opening of the second light duct 23 surrounds the emitting area of the second light source 13. Further, a side of the deflection unit 20 opposed to the attachment side of the deflection unit 20 is inclined with respect to the attachment side forming an inclination angle between the attachment side and the opposed side of the deflection unit 20. Accordingly, each side of each duct 21, 22, 23 with a maximum distance to the origin of the inclination angle is longer than each side of each duct 21, 22, 23 with a minimum distance to the origin of the inclination angle. The deflection members 21a, 22a, 23a are arranged on such longer side of the respective ducts 21, 22, 23 to allow the optical path of the imaging device 11 and the light of the first light source 12 and the second light source 13 to be deflected without obstructed by the respectively opposed shorter side. According to the exemplary embodiment, each of the deflection members 21a, 22a, 23a is a plane parallel deflection mirror. With the light emitted by the first light source 12 and the light emitted by the second light source 13 being parallel to the optical path of an image to be received by the imaging device 11, the inclination angles of the deflection members 21a, 22a, 23a differ from each other and are configured to deflect all paths on the same region of an object 30. The different inclination angles are provided by different inclination of portions of the respective ducts 21, 22, 23 for receiving the plane parallel deflection members. In other embodiments, the different inclination angles may be provided by the deflection members itself, e.g. by deflection mirrors deviating from a plane parallel configuration.

[0063] For adjusting or changing a deflection angle, the control device 14 is configured to adapt the emitting angle of the first light source 12 and/or the second light source and/or the optical path to be received by the imaging device 11 by tilting the first light source 12, the second light source 13 and/or the imaging device 11 and/or an optical component thereof. In alternative embodiments, the deflection members may be controlled to provide an adjustable deflection angle, e.g. by controlling a drive of the respective deflection members 21a, 22a, 23a to tilt the deflection members 21a, 22a, 23a to provide a predetermined deflection angle.

[0064] FIG. 2 shows a schematic perspective top view of the deflection unit 20 attachable to the imaging unit 10 of the imaging system 1 according to FIG. 1. Next to the imaging duct 21, the first light duct 22 and the second light duct 23, the deflection unit 20 comprises two attachment members 24 and a locking member 25. The attachment members 24 are arranged on opposing lateral sides of the deflection unit 20 with respect to the attachment surface of the deflection unit 20. The locking member 25 is arranged on the attachment surface adjacent to a lateral side different from the lateral sides providing the attachment members 24. Due to the spatial separation of the attachment members 24 and the locking member 25 an accessibility of each of the members 24, 25 not obstructed by the other member 24, 25 and any ambiguity error may be avoided. The attachment members 24 are configured to releasably attach the deflection unit 20 to the image unit 10 while the locking member 25 locks the deflection unit 20 to the imaging unit 10 against an unintended detachment. According to the exemplary embodiment, the locking member 25 is further configured to form a hinged joint to allow the deflection unit 20 to be moved out of the optical path and the light paths while still being affixed to the imaging unit 10.

[0065] According to the specific configuration of the attachment members 24 and the locking member 25, FIG. 3 shows a schematic side view of the exemplary deflection unit 20 of FIG. 2. The attachment members 24 are configured as snap-fit attachment members. Each attachment member 24 provides a resilient arm extending from the lateral side of the deflection unit in a direction to the imaging unit 10 or in a direction perpendicular to the plane defined by the attachment surface, respectively. A free end of each of the attachment members 24 comprises a least one snap-fit member (not shown in this perspective), e.g. a hook or protrusion protruding inwardly from the resilient arm. In turn, the imaging unit 10 provides corresponding recesses to receive the snap-fit members. To further secure the deflection unit 20 to the imaging unit 10 of the locking member 25, the locking member 25 extends perpendicular from the attachment surface of the deflection member 20. A free end of the locking member is configured as eyelet to be locked to the imaging unit 10 by a splint pin passing through the eyelet of the locking member and a corresponding eyelet of the imaging unit 10.

[0066] Further, FIG. 3 shows an exemplary cover 40 releasably attached to the deflection unit 20. Here, the cover 40 is a sterile cover with two opposed cover attachment members 41. Similarly to the attachment members 24, the cover attachment members 41 are configured as snap-fit attachment members to engage with corresponding recesses of the deflection unit 20.

[0067] According to the exemplary embodiment of the imaging system 1, a tool center point is associated with the imaging unit 10. The tool center point is a reference point for a controlled movement of the imaging unit 10, e.g. by a robotic arm. Consequently, an imaging focus of the imaging unit 10 should comply with a predetermined position with respect to such tool center point according to a predetermined movement. The tool center point may be set as a factory setting for the imaging unit 10 or the imaging system 1, respectively. However, as components of the imaging system 1, like optical elements or drives, may be subject to changes, e.g. due to environmental boundary conditions, replacements or the like, at least some positions of the imaging focus of the imaging unit 10 may differ from target positions with respect the pre-set tool center point as reference point. In other words, the actual tool center point may be shifted with respect to the pre-set tool center point or initial tool center point, respectively. Specifically, the tool center point may be subject to such change when the deflection unit 10 is attached to the imaging unit 10 due to tolerances with regard to the attachment position, the positioning and inclination angle of the deflection members 21a, 22a, 23a and/or the deflection members 21a, 22a, 23a as such. To reflect the change of the tool center point, the present invention is also directed to a method for calibrating a medical imaging system. Even though the method is described with reference to the exemplary imaging system 1, the method is also applicable for other medical imaging systems or imaging units subject to a calibration requirement.

[0068] FIG. 4A is a schematic representation of the imaging unit 10 of the imaging system 1 according to FIG. 1 in a first position and in a second position according to an exemplary embodiment of a method for calibrating a medical imaging system with an initial tool center point corresponding to a calibrated tool center point. FIG. 4A shows the imaging unit 10 and a respective optical path of the imaging device 11. For reasons of clarity, the light emitted from the first light source 12 and the second light source 13 are not shown in the illustration. The first position of the imaging unit 10 is indicated by solid lines while the second position is indicated by dotted lines.

[0069] The imaging unit 10 is moved to a first position with an imaging focus of the imaging unit 10 being directed to a region of interest ROI defining an initial tool center point. Accordingly, the region of interest ROI is set as reference in correspondence with a pre-set tool center point. The region of interest ROI comprises a QR-code as predetermined imaging artefact. The imaging unit 10 records a first image of the region of interest ROI comprising the QR-code in the first position by the imaging device 11. Subsequently, the imaging unit 10 is rotated around the region of interest ROI along a circumferential path into a second position. Thus, the region of interest ROI defines a center of rotation for the circumferential movement of the imaging unit 10 in the second position with a constant distance between imaging unit 10 and the region of interest ROI with respect to the first position. The imaging device 11 of the imaging unit 10 records a second picture in the second position. The first image and second image are compared by an image processing unit to identify a deviation between the first image and the second image based on a potential deviation between the initial tool center point and an actual tool center point. The image processing unit in the exemplary embodiment is incorporated in the control unit 14 of the imaging unit 10. Since the movement of the imaging unit 10 from the first position to the second position provides different viewing angles, the image processing unit is configured to consider the different viewing angles when comparing the first image and the second image. Preferably, in order to reduce the amount of data to be compared by the image processing unit, the image processing unit is configured to compare any deviations in the QR-code as an example of an imaging artefact with respect to a change of a position within the first image and the second image. The different viewing angles are thereby compensated by the image processing unit to exclude a respective influence on the comparison. Further, a predetermined threshold is set in the control unit 14 that corresponds to a deviation requiring an adaption of the tool center point.

[0070] According to FIG. 4A the imaging focus of the imaging unit 10 in the second position corresponds to the imaging focus of the imaging unit 10 in the first position. Consequently, there is no deviation between the image artefact with respect to a positional change within the second image with reference to the first image. The identified (missing) deviation is therefore below the predetermined threshold. Accordingly, the control unit 14 sets the initial tool center point as calibrated tool center point. The calibrated tool center point is applied as reference point for subsequent movements and/or reorientations of the imaging unit 10 or the imaging device 11, respectively.

[0071] FIG. 4B is a further schematic representation of the imaging unit 10 of the imaging system 1 according to FIG. 1 in the first position and in the second position according to the exemplary embodiment of the method for calibrating a medical imaging system with the initial tool center point deviating from a calibrated tool center point.

[0072] As apparent from FIG. 4B, the optical path of the imaging device 11 of the imaging unit 10 slightly deviates from a perpendicular orientation with respect to the imaging side. Consequently, the first position of the imaging unit 10 to image the region of interest ROI in FIG. 4B differs from the first position of the imaging unit 10 to image the region of interest ROI in FIG. 4A. Due to the difference or the misalignment of the optical path as per FIG. 4B, the position of the imaging focus in the second position differs from the position of the imaging focus in the first position. The difference is detected by the comparison between the first image recorded by the imaging unit 10 in the first position and the second image recorded by the imaging unit 10 in the second position by the image processing unit. The deviation of the imaging focus corresponds to the deviation of the image artefact in the second image with respect to the first image. FIG. 4B represents a deviation above the predetermined threshold for setting a new tool center point. Therefore, the control unit 14 recalculates a calibrated tool center point different from the initial tool center point based on the identified deviation. The calibrated tool center point is applied as new reference point for subsequent movements and/or reorientations of the imaging unit 10 or the imaging device 11, respectively.

[0073] In alternative embodiments of the method for calibrating a medical imaging system, the medical imaging system is adjusted such that the initial tool center point complies with the calibrated tool center point. In other words, the initial tool center point is still set as reference point, while the recalculated calibrated tool center point is applied to control a correction movement of the imaging system with respect to the initial tool center point. In particular, if a misalignment requires only correction in some areas of movement, the tool center point has not to be adjusted as such but may only require a compensation of the moving path in such areas.

[0074] It is to be noted that the given examples are specific embodiments and not intended to restrict the scope of protection given in the claims. In particular, single features of one embodiment may be combined with another embodiment. For example, the method for calibrating a medical imaging device is not restricted to a medical imaging device comprising a deflection unit but may also be applied for other imaging systems.

LIST OF REFERENCE SIGNS

[0075] 1 medical imaging system [0076] 10 imaging unit [0077] 11 imaging device [0078] 12 first light source [0079] 13 second light source [0080] 14 control device [0081] 20 deflection unit [0082] 21 imaging duct [0083] 21a imaging deflection member [0084] 22 first light duct [0085] 22a first light deflection member [0086] 23 second light duct [0087] 23a second light deflection member [0088] 24 attachment member [0089] 25 locking member [0090] 30 object [0091] 40 cover [0092] 41 cover attachment member [0093] ROI region of interest