MICROSCOPE CAMERA CALIBRATION

Abstract

The present disclosure relates to a computer-implemented method for calibrating an optical system of a surgical microscope, a corresponding computer program, a computer-readable storage medium storing such a program and a computer executing the program, as well as a medical system comprising an electronic data storage device and the aforementioned computer. The present disclosure further relates to a computer-implemented method, a computer program and a system for determining the spatial position of an object to be tracked not only via the surgical microscope, but also via a separate detection system. In case a deviation between the detected spatial positions is recognized, the optical system of the surgical microscope is re-calibrated.

Claims

1. A computer-implemented method of calibrating an optical system of a surgical microscope, the method comprising: acquiring first position data via the optical system having a first calibration, wherein the first position data describes an estimated spatial position of an associated object within a first co-ordinate system assigned to the optical system; acquiring second position data is via a detection system separate from the optical system, wherein the second position data describes a spatial position of the associated object within a second co-ordinate system assigned to the detection system; acquiring transformation data that describes a co-ordinate transformation between the first co-ordinate system and the second co-ordinate system; determining calibration data based on the first position data, the second position data, and the transformation data, wherein the calibration data describes a second calibration of the optical system for which the spatial position of the associated object acquired via the optical system using the second calibration would align with the spatial position of the associated object acquired via the detection system; and acquiring adjusted first position data is via the optical system using the second calibration, wherein the adjusted first position data describes a corrected spatial position of the associated object within the first co-ordinate system assigned to the optical system.

2. The method according to claim 1, wherein the first calibration and/or the second calibration of the optical system comprises at least one of: an intrinsic calibration of a camera of the surgical microscope; and/or an extrinsic calibration of the camera of the surgical microscope with respect to a camera of the detection system; and/or wherein the second calibration partially reflects the first calibration.

3. The method according to claim 1, wherein: the acquiring the first position data comprises detecting a distal section of the associated object and/or the acquiring the second position data comprises detecting a proximal section of the associated object; and the determining the calibration data comprises determining the calibration data based on object model data that describes a predefined relative position between the distal section and the proximal section.

4. The method according to claim 1, wherein the acquiring the first position data determining the first position data from one or more images received from a camera integrated with the surgical microscope.

5. The method according to claim 1, wherein the acquiring the first position data comprises acquiring the first position data using a camera of the surgical microscope (2) hashaving one or more of a variable zoom-setting and/or a variable focus-setting.

6. The method according to claim 1, wherein the acquiring the second position data comprises determining the second position data from one or more images received from a camera of the detection system, being separate from a camera of the surgical microscope, wherein the camera of the detection system is rigidly coupled with the surgical microscope and/or is comprises a component separate from the surgical microscope.

7. The method according to claim 6, wherein: the camera of the detection system has a larger field of view than the camera of the surgical microscope camera; and/or the camera of the detection system has a visual axis that is angled with respect to a visual axis of the camera of the surgical microscope.

8. The method according to claim 7, wherein the camera of the detection system comprises a predefined zoom-setting and/or a predefined focus-setting.

9. The method according to claim 1, further comprising acquiring the first, second and transformation data, determining the calibration data, and acquiring the adjusted first position data: upon user request; before the surgical microscope is operated; in predefined time intervals during the operation of the surgical microscope; after a setting of the surgical microscope has been changed, after a viewing direction of the surgical microscope and/or a viewing distance of the surgical microscope has changed; and/or after a setup of a zoom-setting of the optical system and/or a focus-setting of the optical system has changed.

10. The method according to claim 1, further comprising: determining deviation data based on the first position data, the second position data and the transformation data, the deviation data describing a spatial deviation between the spatial position of the associated object acquired via the optical system and the spatial position of the associated object acquired via the detection system, wherein the determining the calibration data comprises selectively determining the calibration data based on the spatial deviation exceeding a predefined threshold.

11. The method according to claim 1, further comprising simultaneously the spatial position of the associated object based on the adjusted first position data and the second position data, wherein the spatial position within at least one degree of freedom is determined based on a weighted combination of the adjusted first position data and the second position data.

12. The method according to claim 1, further comprising tracking the spatial position of the associated object exclusively based on the adjusted first position data, at least for a time period for which the second position data is not received from the detection system.

13. A computer program comprising instructions that, when executed by a processor of an associated computer, cause the associated computer to carry out a method comprising: acquiring first position data via the optical system having a first calibration, wherein the first position data describes an estimated spatial position of an associated object within a first co-ordinate system assigned to the optical system; acquiring second position data via a detection system separate from the optical system, wherein the second position data describes a spatial position of the associated object within a second co-ordinate system assigned to the detection system; acquiring transformation data that describes a co-ordinate transformation between the first co-ordinate system and the second co-ordinate system; determining calibration data based on the first position data, the second position data, and the transformation data, wherein the calibration data describes a second calibration of the optical system for which the spatial position of the associated object acquired via the optical system using the second calibration would align with the spatial position of the associated object acquired via the detection system; and acquiring adjusted first position data via the optical system using the second calibration, wherein the adjusted first position data describes a corrected spatial position of the associated object within the first co-ordinate system assigned to the optical system.

14. A medical system, comprising: at least one computer; at least one electronic data storage device storing transformation data; and a surgical microscope arranged to observe a medical procedure carried out on an associated patient, wherein the at least one computer is operably coupled with: the at least one electronic data storage device for acquiring, from the at least one data storage device, the transformation data; and the surgical microscope for issuing a control signal to the surgical microscope for controlling the operation of the surgical microscope based on calibration data.

15. (canceled)

16. The medical system according to claim 14, wherein the at least one computer is operable to execute instructions stored in the at least one electronic data storage device to calibrate an optical system of the surgical microscope by: acquiring first position data via the optical system having a first calibration, wherein the first position data describes an estimated spatial position of an associated object within a first co-ordinate system assigned to the optical system; acquiring second position data via a detection system separate from the optical system, wherein the second position data describes a spatial position of the associated object within a second co-ordinate system assigned to the detection system; acquiring transformation data that describes a co-ordinate transformation between the first co-ordinate system and the second co-ordinate system; determining calibration data based on the first position data, the second position data, and the transformation data, wherein the calibration data describes a second calibration of the optical system for which the spatial position of the associated object acquired via the optical system using the second calibration would align with the spatial position of the associated object acquired via the detection system; acquiring adjusted first position data via the optical system using the second calibration, wherein the adjusted first position data describes a corrected spatial position of the associated object within the first co-ordinate system assigned to the optical system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0088] In the following, the invention is described with reference to the appended figures which give background explanations and represent specific embodiments of the invention. The scope of the invention is however not limited to the specific features disclosed in the context of the figures, wherein

[0089] FIG. 1 illustrates the basic steps of a method according to the first aspect;

[0090] FIG. 2 shows a surgical microscope used in connection with the method according to the first aspect; and

[0091] FIG. 3 is a schematic illustration of the system according to the fifth aspect.

DESCRIPTION OF EMBODIMENTS

[0092] FIG. 1 shows the basic steps of the method according to the first aspect, in which step S11 encompasses acquiring first position data, step S12 encompasses acquiring second position data, step S13 encompasses acquiring transformation data, step S14 encompasses determining calibration data and step S15 encompasses determining adjusted first position data. At least steps S11, S12 and S13 can be performed in any desired order that differs from the order shown in FIG. 1.

[0093] FIG. 2 shows a surgical microscope 2 which may be used in connection with the present invention.

[0094] The surgical microscope 2 is carried by a movable trolley (not indicated in FIG. 2) which may comprise a computer 13 having at least one processor for performing the method steps outlined in FIG. 1.

[0095] The surgical microscope 2 further includes an optical system 1 for guiding an optical path of a received image to a stereoscopic camera 9 as well as to the microscope’s eyepieces (not indicated in FIG. 2). A detection system 5 having a monoscopic camera 10 is rigidly attached to the housing of the surgical microscope 2 and to the optical system 1 thereof. Thus, the relative position between the co-ordinate system 4 assigned to the optical system 1 and the co-ordinate system 6 assigned to the detection system 5 remains invariant. Thus, a transformation matrix between the co-ordinate systems 4 and 6 remains invariant, as well.

[0096] In the situation shown in FIG. 2, the distal portion 7 of the instrument 3 is located within the field of view of the microscope cameras 9 such that the spatial position thereof can be determined within co-ordinate system 4 based on data derived from the images received by the microscope cameras 9. In a similar manner, the spatial position of the proximal portion 8 can be determined within co-ordinate system 6 based on the image data received by camera 10. Due to the known and predefined spatial arrangement of co-ordinate systems 4 and 6 with respect to each other, the spatial position of sections 7 and 8 can also be transformed to the respective other co-ordinate system 4, 6. Further, the known and predefined spatial arrangement of the instrument portions 7 and 8 relative to each other allows a comparison of the spatial positions of the instrument 3 as detected by the detection system 5 and the microscope 2 respectively.

[0097] In case the focus and/or zoom of the microscope cameras 9 is altered, for example upon request of a surgeon operating the microscope 2, a correct calibration of the microscope cameras 9 can be verified by comparing the spatial position of the object as indicated by the 2D-marker at the distal portion which is detected by camera 10, with the spatial position of the instrument 3 as indicated by the ring markers at the distal portion 7 which are detected by cameras 9. In case an undesired deviation in the object’s position is determined, a re-calibration of the microscope cameras 9 can be initiated, such that the object’s spatial position acquired via the microscope 2 aligns with the object’s spatial position acquired via the detection system 5.

[0098] After the microscope cameras 9 have been re-calibrated, the object’s spatial position can be accurately tracked via the microscope cameras 9 having a new focus-setting and/or zoom-setting.

[0099] FIG. 3 is a schematic illustration of the medical system 1 according to the fifth aspect. The system is in its entirety identified by reference sign 1 and comprises a computer 2, an electronic data storage device (such as a hard disc) 3 for storing at least the patient data and a medical device 4 (such as a radiation treatment apparatus). The components of the medical system 1 have the functionalities and properties explained above with regard to the fifth aspect of this disclosure.