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Fast calibration of electromagnetically tracked oblique-viewing rigid endoscopes

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Abstract

Purpose

The oblique-viewing (i.e., angled) rigid endoscope is a commonly used tool in conventional endoscopic surgeries. The relative rotation between its two moveable parts, the telescope and the camera head, creates a rotation offset between the actual and the projection of an object in the camera image. A calibration method tailored to compensate such offset is needed.

Methods

We developed a fast calibration method for oblique-viewing rigid endoscopes suitable for clinical use. In contrast to prior approaches based on optical tracking, we used electromagnetic (EM) tracking as the external tracking hardware to improve compactness and practicality. Two EM sensors were mounted on the telescope and the camera head, respectively, with considerations to minimize EM tracking errors. Single-image calibration was incorporated into the method, and a sterilizable plate, laser-marked with the calibration pattern, was also developed. Furthermore, we proposed a general algorithm to estimate the rotation center in the camera image. Formulas for updating the camera matrix in terms of clockwise and counterclockwise rotations were also developed.

Results

The proposed calibration method was validated using a conventional \(30{^{\circ }}\), 5-mm laparoscope. Freehand calibrations were performed using the proposed method, and the calibration time averaged 2 min and 8 s. The calibration accuracy was evaluated in a simulated clinical setting with several surgical tools present in the magnetic field of EM tracking. The root-mean-square re-projection error averaged 4.9 pixel (range 2.4–8.5 pixel, with image resolution of \(1280 \times 720)\) for rotation angles ranged from \(-40.3{^{\circ }}\) to \(174.7{^{\circ }}\).

Conclusions

We developed a method for fast and accurate calibration of oblique-viewing rigid endoscopes. The method was also designed to be performed in the operating room and will therefore support clinical translation of many emerging endoscopic computer-assisted surgical systems.

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References

  1. 1.

    Tsai RY (1987) A versatile camera calibration technique for high-accuracy 3-D machine vision methodology using off-the-shelf TV cameras and lenses. IEEE J Robot Automat 3:323–344

  2. 2.

    Heikkila J, Silven O (1997) A four-step camera calibration procedure with implicit image correction. In: Proceedings of IEEE computer society conference computer vision pattern recognition, pp 1106–1112

  3. 3.

    Zhang Z (1999) Flexible camera calibration by viewing a plane from unknown orientations. In: Proceedings of international conference on computer vision, pp 666–673

  4. 4.

    Bouguet JY (2016) Camera calibration with OpenCV. http://docs.opencv.org/2.4/doc/tutorials/calib3d/camera_calibration/camera_calibration.html. Accessed 21 Nov 2016

  5. 5.

    Shiu Y, Ahmad S (1989) Calibration of wrist-mounted robotic sensors by solving homogeneous transform equations of the form ax = xb. IEEE Trans Bobot Autom 5(1):16–29

  6. 6.

    Feuerstein M, Mussack T, Heining SM, Navab N (2008) Intraoperative laparoscope augmentation for port placement and resection planning in minimally invasive liver resection. IEEE Trans Med Imaging 27(3):355–369

  7. 7.

    Shekhar R, Dandekar O, Bhat V, Philip M, Lei P, Godinez C, Sutton E, George I, Kavic S, Mezrich R, Park A (2010) Live augmented reality: a new visualization method for laparoscopic surgery using continuous volumetric computed tomography. Surg Endosc 24(8):1976–1985

  8. 8.

    Kang X, Azizian M, Wilson E, Wu K, Martin AD, Kane TD, Peters CA, Cleary K, Shekhar R (2014) Stereoscopic augmented reality for laparoscopic surgery. Surg Endosc 28(7):2227–2235

  9. 9.

    Cheung CL, Wedlake C, Moore J, Pautler SE, Peters TM (2010) Fused video and ultrasound images for minimally invasive partial nephrectomy: a phantom study. Proc Med Image Comput Comput Assist Interv 13(Pt 3):408–415

  10. 10.

    Liu X, Kang S, Plishker W, Zaki G, Kane TD, Shekhar R (2016) Laparoscopic stereoscopic augmented reality: toward a clinically viable electromagnetic tracking solution. J Med Imaging 3(4):045001

  11. 11.

    Yamaguchi T, Nakamoto M, Sato Y, Konishi K, Hashizume M, Sugano N, Yoshikawa H, Tamura S (2004) Development of a camera model and calibration procedure for oblique-viewing endoscopes. Comput Aided Surg 9(5):203–214

  12. 12.

    Wu C, Jaramaz B, Narasimhan SG (2010) A full geometric and photometric calibration method for oblique-viewing endoscopes. Comput Aided Surg 15(1–3):19–31

  13. 13.

    De Buck S, Maes F, D’Hoore A, Suetens P (2007) Evaluation of a novel calibration technique for optically tracked oblique laparoscopes. Proc Med Image Comput Comput Assist Interv 10(Pt 1):467–474

  14. 14.

    Feuerstein M, Reichl T, Vogel J, Traub J, Navab N (2009) Magneto-optical tracking of flexible laparoscopic ultrasound: model-based online detection and correction of magnetic tracking errors. IEEE Trans Med Imaging 28(6):951–967

  15. 15.

    Melo R, Barreto JP, Falcão G (2012) A new solution for camera calibration and real-time image distortion correction in medical endoscopy-initial technical evaluation. IEEE Trans Biomed Eng 59(3):634–644

  16. 16.

    Barreto JP, Roquette J, Sturm P, Fonseca F (2009) Automatic camera calibration applied to medical endoscopy. In: Proceedings of British machine vision conference, pp 1-10

  17. 17.

    Liu X, Plishker W, Zaki G, Kang S, Kane TD, Shekhar R (2016) On-demand calibration and evaluation for electromagnetically tracked laparoscope in augmented reality visualization. Int J Comput Assist Radiol Surg 11(6):1163–1171

  18. 18.

    Franz AM, Haidegger T, Birkfellner W, Cleary K, Peters TM, Maier-Hein L (2014) Electromagnetic tracking in medicine-a review of technology, validation, and applications. IEEE Trans Med Imaging 33(8):1702–1725

  19. 19.

    Maier-Hein L, Franz AM, Birkfellner W, Hummel J, Gergel I, Wegner I, Meinzer HP (2012) Standardized assessment of new electromagnetic field generators in an interventional radiology setting. Med Phys 39(6):3424–3434

  20. 20.

    Liu X, Kang S, Wilson E, Peters CA, Kane TD, Shekhar R (2014) Evaluation of electromagnetic tracking for stereoscopic augmented reality laparoscopic visualization. In: Proceedings of MICCAI workshop on clinical image-based procedures: translational research in medical imaging, vol 8680, pp 84–91

  21. 21.

    Nijkamp J, Schermers B, Schmitz S, de Jonge S, Kuhlmann K, van der Heijden F, Sonke J-J, Ruers T (2016) Comparing position and orientation accuracy of different electromagnetic sensors for tracking during interventions. Int J Comput Assist Radiol Surg 11(8):1487–1498

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Acknowledgements

This work was supported partially by the National Institutes of Health Grant 1R41CA192504. The authors would like to thank Joao P. Barreto a, Ph.D. and Rui Melo of Perceive3D, SA for providing the single-image calibration API. The authors would also like to thank Emmanuel Wilson for his assistance in building the clinical fCalib plate.

Author information

Correspondence to Raj Shekhar.

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The authors declare that they have no conflict of interest.

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Informed consent was obtained from all individual participants included in the study.

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This article does not contain any studies with human participants or animals performed by any of the authors.

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Supplementary material 1 (mp4 63134 KB)

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Liu, X., Rice, C.E. & Shekhar, R. Fast calibration of electromagnetically tracked oblique-viewing rigid endoscopes. Int J CARS 12, 1685–1695 (2017) doi:10.1007/s11548-017-1623-4

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Keywords

  • Camera calibration
  • Single-image calibration
  • Oblique-viewing endoscope
  • Electromagnetic tracking
  • Augmented reality
  • Computer-assisted surgery