Effect of marker position and size on the registration accuracy of HoloLens in a non-clinical setting with implications for high-precision surgical tasks

Laura Perez-Pachon* (Corresponding Author), Parivrudh Sharma, Helena Brech, Jenny Gregory, Terry Lowe, Matthieu Poyade, Flora Gröning

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)
6 Downloads (Pure)

Abstract

Purpose: Emerging holographic headsets can be used to register patient-specific virtual models obtained from medical scans with the patient’s body. Maximising accuracy of the virtual models’ inclination angle and position (ideally, ≤2° and ≤2 mm, respectively, as in currently approved navigation systems) is vital for this application to be useful. This study investigated the accuracy with which a holographic headset registers virtual models with real-world features based on the position and size of image markers.
Methods: HoloLens® and the image-pattern-recognition tool Vuforia Engine™ were used to overlay a 5-cm-radius virtual hexagon on a monitor’s surface in a predefined position. The headset’s camera detection of an image marker (displayed on the monitor) triggered the rendering of the virtual hexagon on the headset’s lenses. 4x4, 8x8 and 12x12cm image markers displayed at nine different positions were used. In total, the position and dimensions of 114 virtual hexagons were measured on photos captured by the headset’s camera.
Results: Some image marker positions and the smallest image marker (4x4 cm) led to larger errors in the perceived dimensions of the virtual models than other image marker positions and larger markers (8x8 and 12x12 cm). ≤2° and ≤2 mm errors were found in 70.7% and 76% of cases, respectively.
Conclusion: Errors obtained in a non-negligible percentage of cases are not acceptable for certain surgical tasks (e.g. the identification of correct trajectories of surgical instruments). Achieving sufficient accuracy with image marker sizes that meet surgical needs and regardless of image marker position remains a challenge
Original languageEnglish
Pages (from-to)955-966
Number of pages12
JournalInternational Journal of Computer Assisted Radiology and Surgery
Volume16
Early online date15 Apr 2021
DOIs
Publication statusPublished - Jun 2021

Bibliographical note

Acknowledgments: We are grateful to Mike Whyment for the purchase of the holographic headset used in this study and to Rute Vieira and Fiona Saunders for their advice on statistics.
We would also like to thank Denise Tosh and the Anatomy staff at the University of Aberdeen for their support. This research was funded by The Roland Sutton Academic Trust (RSAT 0053/R/17) and the University of Aberdeen (via an Elphinstone Scholarship, IKEC Award and Medical Sciences Honours project funding).
Funding: This study was funded by The Roland Sutton Academic Trust (RSAT 0053/R/17) and the University of Aberdeen (via an Elphinstone Scholarship, IKEC Award and Medical Sciences Honours project funding).

Keywords

  • image marker
  • augmented reality
  • Holographic Headsets
  • registration error
  • image-guided surgery

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