Image-based marker tracking and registration for intraoperative 3D image-guided interventions using augmented reality
This addresses the need for precise intraoperative guidance in medical interventions, though it is incremental as it builds on existing marker-based registration methods.
The paper tackled the problem of quickly and accurately registering CT scans with patients for augmented reality-guided surgery by using radio-opaque QR-code markers, achieving alignment in 0.9 ± 0.2 seconds with an accuracy of 5 ± 2 mm.
Augmented reality has the potential to improve operating room workflow by allowing physicians to "see" inside a patient through the projection of imaging directly onto the surgical field. For this to be useful the acquired imaging must be quickly and accurately registered with patient and the registration must be maintained. Here we describe a method for projecting a CT scan with Microsoft Hololens and then aligning that projection to a set of fiduciary markers. Radio-opaque stickers with unique QR-codes are placed on an object prior to acquiring a CT scan. The location of the markers in the CT scan are extracted and the CT scan is converted into a 3D surface object. The 3D object is then projected using the Hololens onto a table on which the same markers are placed. We designed an algorithm that aligns the markers on the 3D object with the markers on the table. To extract the markers and convert the CT into a 3D object took less than 5 seconds. To align three markers, it took $0.9 \pm 0.2$ seconds to achieve an accuracy of $5 \pm 2$ mm. These findings show that it is feasible to use a combined radio-opaque optical marker, placed on a patient prior to a CT scan, to subsequently align the acquired CT scan with the patient.