Perspective pinhole model with planar source for augmented reality surgical navigation based on C-arm imaging

Abstract

We validated that intrinsic parameters that describe the source position were dependent on depth for a three-dimensional object and showed that displacement can be reduced and become independent of depth by using the proposed planar source model.

Toward an End-to-End Calibration for Mobile C-Arm in Combination with a Depth Sensor for Surgical Augmented Reality Applications

“…In addition, there are some studies, such as [15,16], for registration of Computed Tomography (CT) data to intra-operative 3D surface data in surgical AR. However, these systems are limited to work with only the CT C-arm, which provides 3D volume, and it cannot be applied in operating rooms with 2D Fluoroscopic C-arm imaging systems.…”

“…Intrinsic parameters of the C-arm imaging system cannot be considered constant over the image series because of minor torsion of the C-arm caused by the weights of X-ray source and detector [15,17]. Instability in C-arm interior orientation (IO) is an essential factor which severely limits the accuracy of measurements.…”

“…Moreover, we should also consider the instability and correlation between calibration parameters during the C-arm movement to improve accuracy. Therefore, we extended the idea of a virtual detector as a reference imaging plane for updating the intrinsic parameters during the surgery because of the instability of parameters [15]. For this purpose, we designed marker plates with several small ball-bearings (BBs), as fiducial markers, attached to the X-ray focus (cf.…”

“…It also limited the field of view and workspace of the surgeon [1,6].Habert et al [8] and Habert [7] attached RGB-D sensors to the C-arm X-ray source and applied Zhang's method [9] with a multi-modal planar phantom in order to obtain the calibration parameters without mirrors. For calibration in the surgical AR navigation with C-arm, current studies, such as [10][11][12][13][14], have also used Zhang's method [9].In addition, there are some studies, such as [15,16], for registration of Computed Tomography (CT) data to intra-operative 3D surface data in surgical AR. However, these systems are limited to work with only the CT C-arm, which provides 3D volume, and it cannot be applied in operating rooms with 2D Fluoroscopic C-arm imaging systems.…”

“…However, in state of the art methods for most of the researches, the intrinsic camera parameters of C-arm are assumed to be constant. A few investigations, such as [15,17], considered this issue for C-arm calibration. Ignorance of instability in intrinsic parameters can lead to high distortions and errors.…”