Search

In a paired-point rigid registration, target registration error (TRE) is deemed to be the most important quality metric. TRE usually cannot be directly measured, and thus many TRE estimation algorithms have been proposed. However, target localization errors (TLEs) in two spaces are not considered in the definition of TRE. In this paper, we propose a new type of evaluation metric that is referred to as total TRE (TTRE) at a given target point with TLE incorporated. Statistics including mean, root mean square (rms), and covariance matrix of TTRE are derived without making any assumption of the TLE magnitude. TTRE and fiducial registration error (FRE) are proved to be uncorrelated when an ideal weighting scheme is adopted in solving the registration problem. The proposed error model is validated through extensive experiments. In the first experiment with random fiducials and targets, in 90% of the test cases, there shows no difference between the predicted and simulated TTRE statistics when six fiducials are used. In the second experiment of deep-brain stimulation surgery, the mean value of CC(TTRE,FRE) being $8.9246\times 10^{-4}\pm 0.0389 $ was observed, which indicates that TTRE and FRE are uncorrelated. In the third experiment of surgical tool-tip tracking, the mean and standard deviation of percentage differences between predicted and simulated TTRE rms values are $2.22\%\pm 0.77\%$ for the planar tool and $2.62\%\pm 0.59\%$ for the textral tool. In summary, our proposed algorithm can well model the TTRE metric. Note to Practitioners—This paper was motivated by considering the existence of target localization error in two spaces to be registered in a rigid point-based registration. Given fiducial localization error (FLE) and TLE probability distributions, the proposed TTRE model gives the covariance matrix and root mean square of TTRE at a given target point. The possible applications of the proposed TTRE model in an image-guided surgery (IGS) include: 1) estimation of surgical tool-tip tracking error distribution when pivot calibration uncertainty is considered; 2) accuracy evaluation of an image-to-patient registration; 3) updating of a preoperative surgical plan on a computed tomography/MRI image to consider the registration error at a given target point; and 4) estimation of real-time tool-tip error in touching a desired “true” surgical target, such as a tumor during surgery. To use the proposed error estimation algorithm, FLE and TLE in two spaces to be registered have to be known or estimated in advance to a registration process. The proposed error model is validated through extensive simulations. [ABSTRACT FROM AUTHOR]

This paper presents a passive-marker-based optical tracking system utilizing dual Kinect sensors and additional custom optical tracking components. To obtain sub-millimeter tracking accuracy, we introduce robust calibration of dual infrared sensors and point correspondence establishment in a stereo configuration. The 3D localization is subsequently accomplished using multiple back projection lines. The proposed system extends existing inexpensive consumer electronic devices, implements tracking algorithms, and shows the feasibility of applying the proposed low-cost system to surgical training for computer assisted surgeries. [ABSTRACT FROM AUTHOR]

Natural orifice translumenal endoscopic surgery (NOTES) is the latest surgery paradigm in which the abdominal cavity is accessed via the body's natural orifice, e.g., vagina, mouth, etc. Compared with traditional laparoscopic surgery, NOTES completely eliminates the skin incision and therefore benefits the patients in several aspects such as less post-operative pain, shorter recovery period, fewer complications, etc. Due to the unique characteristics of NOTES, instruments for traditional laparoscopic surgery are not suitable for NOTES and hence novel hardware design is necessary for facilitating system development. This paper gives an overview of the state of the arts in the development of surgical instruments for NOTES, particularly with a focus on the promising robotic endoscopes. [ABSTRACT FROM AUTHOR]

A family of passive echogenic markers is presented by which the position and orientation of a surgical instrument can be determined in a 3-D ultrasound volume, using simple image processing. Markers are attached near the distal end of the instrument so that they appear in the ultrasound volume along with the instrument tip. They are detected and measured within the ultrasound image, thus requiring no external tracking device. This approach facilitates imaging instruments and tissue simultaneously in ultrasound-guided interventions. Marker-based estimates of instrument pose can be used in augmented reality displays or for image-based servoing. Design principles for marker shapes are presented that ensure imaging system and measurement uniqueness constraints are met. An error analysis is included that can be used to guide marker design and which also establishes a lower bound on measurement uncertainty. Finally, examples of marker measurement and tracking algorithms are presented along with experimental validation of the concepts. [ABSTRACT FROM PUBLISHER]

Registration is an essential problem in image-guided surgery (IGS) since it brings different involved coordinate frames together. Nonrigid or deformable registration still faces many challenges, such as two point sets (PSs) are partially overlapped. To tackle the challenges in the nonrigid registration, we introduce a new two-step point-based registration pipeline that includes two steps. In the first step, the rigid transformation between the two spaces is recovered where the orientation vectors are adopted. In the second step, built on the nonrigid coherent point drift (CPD) approach, the anisotropic positional noise is also assumed. Registration results on the human liver verify the proposed approach’ great improvements over the other methods. First, the rotation and translation are recovered with smaller error values than the existing methods. Second, our registration method’s performance is much more robust to the partial overlapping between two PSs. Third, the two-step registration framework achieves the best performances in most test cases when there is a localization error in acquiring the intraoperative data. Note to Practitioners—A novel registration approach is presented for image-guided liver surgery (LGLS). Compared with existing nonrigid registration methods, two significant changes (or improvements) exist in the proposed registration framework: 1) the normal vectors are extracted and utilized in the rigid registration step and 2) the anisotropic positional uncertainties are considered. In both steps, the registration problems are formulated as a maximum likelihood (ML) problems and dealt with the expectation-maximization (EM) technique. In both steps, the matrix form of the updated positional covariance is provided and can speed up the computational process. The readers are reminded that with extra information and a more general positional error assumption, our approach demonstrates improved performances in the case of partial-to-full alignment. [ABSTRACT FROM AUTHOR]

This paper presents a sensor fusion-based surgical instrument tracking system which uses multiple monocular modules. The system is an optical tracking system, which has been widely utilized in the image-guide surgery because of its high accuracy and precision. However, the line-of-sight occlusion problem which remains unresolved in current systems frustrates surgeons during the operation. To address this challenge, we propose a surgical instrument tracking system based on multiple monocular modules. The rationale is to enable the system to track the surgical instruments inside the surgical site from different views. Three sensor fusion algorithms are proposed to integrate all sensor data from the multimodule system. In order to show the feasibility of the tracking system, simulations and comparison experiments have been carried out. The intensive investigation results give a practical instruction to the real implementation of the proposed system in image-guided interventions. Moreover, an image-guided surgical trial by using a cadaver head has been carried out to validate the feasibility of the proposed system and the tracking algorithms. The results from both the simulation and the cadaver trial have shown the effectiveness of the proposed robust fusion algorithm. Note to Practitioners—Optical tracking system (OTS) for image-guided surgery has suffered from line-of-sight (LoS) occlusion and field-of-view (FoV) limitation problems for a long time; nevertheless, no satisfactory solution has been given yet. In the real-world practice, surgeons and assistants have to manually adjust the position and orientation of the optical tracker during operation. This interrupts the surgery process and degrades the efficiency of the surgical procedure. Instead of using one tracker for the image-guided surgery, our approach is to utilize distributed modular trackers to avoid LoS occlusion and maintain FoV of the OTS. Based on our previous work, this paper is to provide an optimal fusion algorithm that takes the advantage of the multiple modules and validate the system in both the simulation and the real-world surgical environment. [ABSTRACT FROM AUTHOR]

Optical means of instrument tracking has been widely used in image-guided interventions and considered the de facto standard for tracking rigid bodies with a direct line-of-sight. However, the occlusion problem which remains unresolved in current systems frustrates surgeons during the operation. To address this challenge, we propose a surgical instrument tracking system based on multiple reconfigurable monocular modules. The main approach is to enable the system to dynamically reconfigure the multiple monocular modules when occlusion occurs partially within the workspace. In this paper, we focus on the system architecture and an agile multicamera calibration method which only uses the customized tool for the surgical instrument tracking scenario. Additionally, two fast non-iterative algorithms are proposed and studied. In order to show the feasibility and superiority of the corresponding multicamera calibration algorithm, comparison experiments have carried out. The intensive investigation results give a practical instruction to the real implementation of the proposed system in image-guided interventions. [ABSTRACT FROM PUBLISHER]