Dynamic Reference Frame Research Articles

Removal of Foreign Body Aided with Various Navigation Modalities: A Case Report and Literature Review

<i>Background</i>: Computerized surgical navigation (CSN) has many potential applications in foreign body (FB) removal. <i>Case report</i>: While playing, a 14-year-old girl was accidentally shot in the facial area with a shotgun. Removal of the superficial shots and of the left eyeball was performed at a local hospital. She was transferred to the West China Hospital of Stomatology (Sichuan, China) on the third day after the accident due to difficulties in removing the remaining shots. Except for left eye vision loss, there was no abnormal physical or laboratory test. Spiral computed tomography (CT) scan of the head was performed and data were imported into the <i>iplan</i> software of the VectorVision² navigation system. A dynamic reference frame was fixed to the skull and another to the forceps. Eight shots were successfully removed. One shot could not be removed because of significant shifting. At 1 month, the incisions were successfully healed and there were no symptoms or signs. <i>Conclusion</i>: The case presented here and the relevant literature about CSN indicates that CSN is a valuable modality for the removal of FBs, not only in the craniomaxillofacial area, but anywhere in the body.

A Similarity Method of Color Frequency Histogram With Dynamic Reference Frame for Image Visual Titrations

Visual titration is an important method for detecting the main and minor components in the samples. In visual titration, the image features are easily affected by the dichroism of the indicator, ambient light, and bubbles in the solution, which adversely affect the precision of titration endpoint recognition. This article proposes a similarity method of image color frequency histograms with dynamic reference frames (SHDRFs) for addressing the problems of color frequency histograms of time-varying and time-shifting characteristics in image visual titrations. With this method, the similarity was redefined as the difference between the color frequency histograms of the two images with a simple and efficient calculation. The titration curve was established based on the similarity values, and the titration endpoint was located by the threshold line of the similarity. To prove feasibility and effectiveness of this method, six zinc electrolyte samples were configured for titrations. Compared with the concentrations of the samples, there was no significant systematic deviation of the concentrations of sulfuric acid and zinc ions between the results detected through this method and their corresponding true concentrations through a one-sample $t$ -test at the 95% confidence level.

A conceptual essay on the nature of spacetime

A conceptual essay on the nature of spacetime

Quantitative Augmented Reality-Assisted Free-Hand Orthognathic Surgery Using Electromagnetic Tracking and Skin-Attached Dynamic Reference.

The purpose of this study was to develop a quantitative AR-assisted free-hand orthognathic surgery method using electromagnetic (EM) tracking and skin-attached dynamic reference. The authors proposed a novel, simplified, and convenient workflow for augmented reality (AR)-assisted orthognathic surgery based on optical marker-less tracking, a comfortable display, and a non-invasive, skin-attached dynamic reference frame. The 2 registrations between the physical (EM tracking) and CT image spaces and between the physical and AR camera spaces, essential processes in AR-assisted surgery, were pre-operatively performed using the registration body complex and 3D depth camera. The intraoperative model of the maxillary bone segment (MBS) was superimposed on the real patient image with the simulated goal model on a flat-panel display, and the MBS was freely handled for repositioning with respect to the skin-attached dynamic reference tool (SRT) with quantitative visualization of landmarks of interest using only EM tracking. To evaluate the accuracy of AR-assisted Le Fort I surgery, the MBS of the phantom was simulated and repositioned by 6 translational and three rotational movements. The mean absolute deviations (MADs) between the simulation and post-operative positions of MBS landmarks by the SRT were 0.20, 0.34, 0.29, and 0.55 mm in x- (left lateral, right lateral), y- (setback, advance), and z- (impaction, elongation) directions, and RMS, respectively, while those by the BRT were 0.23, 0.37, 0.30, and 0.60 mm. There were no significant differences between the translation and rotation surgeries or among surgeries in the x-, y-, and z-axes for the SRT. The MADs in the x-, y-, and z-axes exhibited no significant differences between the SRT and BRT. The developed method showed high accuracy and reliability in free-hand orthognathic surgery using EM tracking and skin-attached dynamic reference.

Realization of an Optimal Dynamic Geodetic Reference Frame in China: Methodology and Applications

China Geodetic Coordinate System 2000 (CGCS2000) has been used for several years as a formal published reference frame. The coordinates of all global navigation satellite system (GNSS) stations in China need to be corrected to align with the CGCS2000 frame. Different strategies can be adopted for the realization of an optimal reference frame. However, different strategies lead to different results, with differences as great as several decimeters when GNSS station coordinates are transformed into CGCS2000-defined coordinates. The two common methods for the coordinate correction of a GNSS station are quasi-stable adjustment under CGCS2000 and plate movement correction, and the differences between their results can be greater than 10 cm. In this study, a statistic method called “supervised clustering” is applied to the selection of GNSS reference stations; a new scheme named “partition spacing” for the grouping of all processed GNSS stations is proposed; and the plate movement correction method is used to correct the coordinates of all GNSS stations from the GNSS epoch to the CGCS2000 epoch. The results from the new partitioning method were found to be significantly better than those from the conventional station-blocking approach. When coordinates from the stations without grouping were used as the standard, the accuracy of all the three-dimensional coordinate components from the new partitioning method was better than 2 mm. The root mean squares (RMSs) of the velocities in the x, y, and z directions resulting from the supervised clustering method were 0.19, 0.45, and 0.32 mm∙a−1, respectively, which were much smaller than the values of 0.92, 0.72, and 0.97 mm∙a−1 that resulted from the conventional approach. In addition, singular spectrum analysis (SSA) was used to model and predict the position nonlinear movements. The modeling accuracies of SSA were better than 3, 2, and 5 mm in the east (E), north (N), and up (U) directions, respectively; and its prediction accuracies were better than 5 mm and 1 cm for the horizontal and vertical domains, respectively.

Frameless Patient Tracking With Adhesive Optical Skin Markers for Augmented Reality Surgical Navigation in Spine Surgery

Observational study. The aim of this study was to evaluate the accuracy of a new frameless reference marker system for patient tracking by analyzing the effect of vertebral position within the surgical field. Most modern navigation systems for spine surgery rely on a dynamic reference frame attached to a vertebra for tracking the patient. This solution has the drawback of being bulky and obstructing the surgical field, while requiring that the dynamic reference frame is moved between vertebras to maintain accuracy. An augmented reality surgical navigation (ARSN) system with intraoperative cone beam computed tomography (CBCT) capability was installed in a hybrid operating room. The ARSN system used input from four video cameras for tracking adhesive skin markers placed around the surgical field. The frameless reference marker system was evaluated first in four human cadavers, and then in 20 patients undergoing navigated spine surgery. In each CBCT, the impact of vertebral position in the surgical field on technical accuracy was analyzed. The technical accuracy of the inserted pedicle devices was determined by measuring the distance between the planned position and the placed pedicle device, at the bone entry point. The overall mean technical accuracy was 1.65 ± 1.24 mm at the bone entry point (n = 366). There was no statistically significant difference in technical accuracy between levels within CBCTs (P ≥ 0.12 for all comparisons). Linear regressions showed that null- to negligible parts of the effect on technical accuracy could be explained by the number of absolute levels away from the index vertebrae (r ≤ 0.007 for all, β ≤ 0.071 for all). The frameless reference marker system based on adhesive skin markers is unobtrusive and affords the ARSN system a high accuracy throughout the navigated surgical field, independent of vertebral position. 3.

Target-centric angle variables in pursuit tracking

A method for constructing a dynamic local reference frame centered at the location of a pursuit target is proposed. It uses original fixed reference frame coordinates for three positions: the location of a moving target, the location of a pursuing entity, and a third reference point that defines the instantaneous target trajectory direction. The method involves rigid body geometric operations and creates a consistent local reference frame configuration having its origin at the target location. The local frame also has the target trajectory pointing in the positive x axis direction, and a defined azimuth plane descriptive of the current pursuer location. This plane is determined by a concluding local frame rotation around the set x axis, which specifies a particular y axis direction. If the pursuer position is not on the local frame’s azimuth plane, its perpendicular projection on to that plane serves as an additional position for use in defining angle variables. Three angle variables relevant to the pursuit dynamics (not all mutually independent) are obtained from the three coordinate values of the pursuer position in the local frame: an elevation angle, an azimuth angle, and a bearing angle that basically describes how far off course the pursuer position is from being directly behind the target’s current trajectory path position. To illustrate the method of obtaining these angles and to demonstrate their potential usefulness in characterizing pursuit behavior, example experimental data from a motor control and coordination pursuit task performance are presented and analyzed.

Towards Optical Imaging for Spine Tracking without Markers in Navigated Spine Surgery.

Surgical navigation systems are increasingly used for complex spine procedures to avoid neurovascular injuries and minimize the risk for reoperations. Accurate patient tracking is one of the prerequisites for optimal motion compensation and navigation. Most current optical tracking systems use dynamic reference frames (DRFs) attached to the spine, for patient movement tracking. However, the spine itself is subject to intrinsic movements which can impact the accuracy of the navigation system. In this study, we aimed to detect the actual patient spine features in different image views captured by optical cameras, in an augmented reality surgical navigation (ARSN) system. Using optical images from open spinal surgery cases, acquired by two gray-scale cameras, spinal landmarks were identified and matched in different camera views. A computer vision framework was created for preprocessing of the spine images, detecting and matching local invariant image regions. We compared four feature detection algorithms, Speeded Up Robust Feature (SURF), Maximal Stable Extremal Region (MSER), Features from Accelerated Segment Test (FAST), and Oriented FAST and Rotated BRIEF (ORB) to elucidate the best approach. The framework was validated in 23 patients and the 3D triangulation error of the matched features was < mm. Thus, the findings indicate that spine feature detection can be used for accurate tracking in navigated surgery.

Hyperspectral Imaging for Skin Feature Detection: Advances in Markerless Tracking for Spine Surgery

In spinal surgery, surgical navigation is an essential tool for safe intervention, including the placement of pedicle screws without injury to nerves and blood vessels. Commercially available systems typically rely on the tracking of a dynamic reference frame attached to the spine of the patient. However, the reference frame can be dislodged or obscured during the surgical procedure, resulting in loss of navigation. Hyperspectral imaging (HSI) captures a large number of spectral information bands across the electromagnetic spectrum, providing image information unseen by the human eye. We aim to exploit HSI to detect skin features in a novel methodology to track patient position in navigated spinal surgery. In our approach, we adopt two local feature detection methods, namely a conventional handcrafted local feature and a deep learning-based feature detection method, which are compared to estimate the feature displacement between different frames due to motion. To demonstrate the ability of the system in tracking skin features, we acquire hyperspectral images of the skin of 17 healthy volunteers. Deep-learned skin features are detected and localized with an average error of only 0.25 mm, outperforming the handcrafted local features with respect to the ground truth based on the use of optical markers.

Removal of Foreign Body Aided with Various Navigation Modalities- A Case Report and Literature Review

Background: Computerized surgical navigation (CSN) has many potential applications in foreign body (FB) removal. Case Report: While playing, a 14-year-old girl was accidentally shot in the facial area with a shotgun. Removal of the superficial shots and of the left eyeball was performed at a local hospital. She was transferred to the West China Hospital of Stomatology (Sichuan, China) on the third day after the accident due to difficulties in removing the remaining shots. Except for left eye vision loss, there was no abnormal physical or laboratory test. Spiral computed tomography (CT) scan of the head was performed and data were imported into the iplan software of the VectorVision2 navigation system. A dynamic reference frame was fixed to the skull and another to the forceps. Eight shots were successfully removed. One shot could not be removed because of significant shifting. At 1 month, the incisions were successfully healed and there were no symptoms or signs. Conclusion: The case presented here and the relevant literature about CSN indicates that CSN is a valuable modality for the removal of FBs, not only in the craniomaxillofacial area, but anywhere in the body.

Accuracy assessment for the co-registration between optical and VIVE head-mounted display tracking.

We report on the development and accuracy assessment of a hybrid tracking system that integrates optical spatial tracking into a video pass-through head-mounted display. The hybrid system uses a dual-tracked co-calibration apparatus to provide a co-registration between the origins of an optical dynamic reference frame and the VIVE Pro controller through a point-based registration. This registration provides the location of optically tracked tools with respect to the VIVE controller's origin and thus the VIVE's tracking system. The positional accuracy was assessed using a CNC machine to collect a grid of points with 25 samples per location. The positional trueness and precision for the hybrid tracking system were [Formula: see text] and [Formula: see text], respectively. The rotational accuracy was assessed through inserting a stylus tracked by all three systems into a hemispherical phantom with cylindrical openings at known angles and collecting 25 samples per cylinder for each system. The rotational trueness and precision for the hybrid tracking system were [Formula: see text] and [Formula: see text], respectively. The difference in position and rotational trueness between the OTS and the hybrid tracking system was [Formula: see text] and [Formula: see text], respectively. We developed a hybrid tracking system that allows the pose of optically tracked surgical instruments to be known within a first-person HMD visualization system, achieving submillimeter accuracy. This research validated the positional and rotational accuracy of the hybrid tracking system and subsequently the optical tracking and VIVE tracking systems. This work provides a method to determine the position of an optically tracked surgical tool with a surgically acceptable accuracy within a low-cost commercial-grade video pass-through HMD. The hybrid tracking system provides the foundation for the continued development of virtual reality or augmented virtuality surgical navigation systems for training or practicing surgical techniques.

Is bony attachment necessary for dynamic reference frame in navigation-assisted minimally invasive lumbar spine fusion surgery?

This study aimed to compare the accuracy of navigation-assisted percutaneous pedicle screw insertions between traditional posterior superior iliac spine (PSIS) fixed and cutaneously fixed dynamic reference frame (DRF) in minimally invasive surgery of transforaminal lumbar interbody fusion (MIS TLIF). This is a prospective randomized clinical study. Between May 2016 and Nov 2017, 100 patients who underwent MIS TLIF were randomly divided into bone fixed group (with PSIS fixed DRF) and skin fixed group (with cutaneously fixed DRF). The pedicel screws were inserted under navigational guidance using computed tomography (CT) data acquired intraoperatively with a Ziehm 3-dimensional fluoroscopy-based navigation system. Screw positions were immediately checked by a final intraoperative scan. The accuracy of screw placement was evaluated by a sophisticated computed tomography protocol. Both groups had similar patient demographics. Totally Five-hundred Twelve pedicle screws were placed in the lumbar spine. There were 2 moderate (2–4 mm) pedicle perforations in each group. The accuracy showed no significant difference between bone fixed and skin fixed DRF. There were no significant procedure-related complications. The skin fixed DRF provides similar accuracy in pedicle screw insertions with bone fixed DRF using intraoperative 3D image guided navigation in MIS TLIF. Skin fixed DRF not only serves as an alternative method but also saves a separate incision wound for bony attachment.

Intraoperative Error Propagation in 3-Dimensional Spinal Navigation From Nonsegmental Registration: A Prospective Cadaveric and Clinical Study.

Study Design:Prospective pre-clinical and clinical cohort study.Objectives:Current spinal navigation systems rely on a dynamic reference frame (DRF) for image-to-patient registration and tool tracking. Working distant to a DRF may generate inaccuracy. Here we quantitate predictors of navigation error as a function of distance from the registered vertebral level, and from intersegmental mobility due to surgical manipulation and patient respiration.Methods:Navigation errors from working distant to the registered level, and from surgical manipulation, were quantified in 4 human cadavers. The 3-dimensional (3D) position of a tracked tool tip at 0 to 5 levels from the DRF, and during targeting of pedicle screw tracts, was captured in real-time by an optical navigation system. Respiration-induced vertebral motion was quantified from 10 clinical cases of open posterior instrumentation. The 3D position of a custom spinous-process clamp was tracked over 12 respiratory cycles.Results:An increase in mean 3D navigation error of ≥2 mm was observed at ≥2 levels from the DRF in the cervical and lumbar spine. Mean ± SD displacement due to surgical manipulation was 1.55 ± 1.13 mm in 3D across all levels, ≥2 mm in 17.4%, 19.2%, and 38.5% of levels in the cervical, thoracic, and lumbar spine, respectively. Mean ± SD respiration-induced 3D motion was 1.96 ± 1.32 mm, greatest in the lower thoracic spine (P < .001). Tidal volume and positive end-expiratory pressure correlated positively with increased vertebral displacement.Conclusions:Vertebral motion is unaccounted for during image-guided surgery when performed at levels distant from the DRF. Navigating instrumentation within 2 levels of the DRF likely minimizes the risk of navigation error.

Design and validation of an open-source library of dynamic reference frames for research and education in optical tracking.

Dynamic reference frames (DRFs) are a common component of modern surgical tracking systems; however, the limited number of commercially available DRFs poses a constraint in developing systems, especially for research and education. This work presents the design and validation of a large, open-source library of DRFs compatible with passive, single-face tracking systems, such as Polaris stereoscopic infrared trackers (NDI, Waterloo, Ontario). An algorithm was developed to create new DRF designs consistent with intra- and intertool design constraints and convert to computer-aided design (CAD) files suitable for three-dimensional printing. A library of 10 such groups, each with 6 to 10 DRFs, was produced and tracking performance was validated in comparison to a standard commercially available reference, including pivot calibration, fiducial registration error (FRE), and target registration error (TRE). Pivot tests showed calibration error [Formula: see text], indistinguishable from the reference. FRE was [Formula: see text], and TRE in a CT head phantom was [Formula: see text], both equivalent to the reference. The library of DRFs offers a useful resource for surgical navigation research and could be extended to other tracking systems and alternative design constraints.

Mandibular Surgical Navigation: An Innovative Guiding Method.

Mandibular osteotomies are usually required to treat craniomaxillofacial disorders. Losses of mandibular continuity result in esthetic and functional deficiency. During the past 30 years, the spread of the computer-assisted surgery techniques, rapid prototyping, and surgical navigation technique has improved the reliability and the outcomes of mandibular resections and reconstructions, by providing realtime feedback to surgeon. Recent studies reported the feasibility and the precision of surgical navigation applied to mandibular surgical resection and reconstruction with fibula flap but none of them describes a method to navigate the jaw allowing its full motility during the operation. To our knowledge, this is the first-time description of such a kind of method to navigate the jaw positioning the dynamic reference frame directly on the mandibular branch to maintain the full mobility of the mandible. The method described in our series has allowed an accurate surgical navigation of the jaw without the need of intermaxillary fixation. This technique could greatly facilitate resection and reconstructive surgical procedures of the jaw while ensuring precision and accuracy. The encouraging results obtained in the present report suggest to further investigate the possibilities of this technique to better define the method and its indications.

Long-Term GNSS Analysis for Local Geodetic Datum After 2011 Tohoku Earthquake

The current Korean national geodetic reference frame, KGD2002, refers to the fixed epoch at 2002·0 under the assumption that there is no crustal movement of the Korean peninsula. A discontinuity in the coordinates of the reference stations may occur due to the relocation of the stations, antenna replacement, or earthquakes. The static reference frame has difficulty in covering continuous and/or discontinuous crustal movements at the same time. A new dynamic local geodetic reference frame has been calculated based on eight years (2007–2014) of Global Navigation Satellite System (GNSS) data. The final geodetic coordinates and velocities were calculated on the basis of the IGb08 reference frame. The discontinuity caused by the 2011 Tohoku earthquake can be addressed using the newly proposed model in this study, which ensures the consistency and continuity of the local geodetic datum.

238 - Error Propagation in Spinal Intraoperative Navigation from Nonsegmental Registration: A Prospective Cadaveric and Clinical Study

BACKGROUND CONTEXT: Computer-assisted navigation may guide spinal instrumentation. Current systems rely on a dynamic reference frame (DRF) for image-to-patient registration and tool tracking. Displacement of levels distant to the DRF may generate inaccuracy from intersegmental mobility. Sources of intersegmental mobility during intraoperative navigation include respiration-induced vertebral motion, as well as displacement due to surgeon manipulation during the placement of instrumentation. In long-segment deformity procedures or in minimally-invasive lumbosacral procedures, with DRF fixation to the pelvis, navigation inaccuracy due to intersegmental mobility can become particularly pronounced.

Application of a newly designed mandibular distraction device for navigation surgery in goats

PurposeThis animal study is to investigate the accuracy of navigation-guided mandibular distraction osteogenesis with a special designed distraction device by TBNavis-CMFS navigation system. Materials and methodsFour goats were included in this study. The 3D simulation unilateral mandibular distraction osteogenesis was simulated for 14 mm lengthening in TBNavis-CMFS navigation system. A new designed mandibular distraction device with the detachable adapter for navigation surgery in combination with the specific mandibular dynamic reference frame was applied. Navigation guided distraction osteogenesis was performed on goats and mandible was gradually distracted according to the simulation. Postsurgical 3-D skeletal measurements of presurgical simulations and postsurgical outcomes were compared statistically. ResultsNavigation assisted distraction osteogenesis was successfully performed and the new designed distraction devices worked uneventful. The accuracy of intra-operative registration was within 1 mm. The mandible was lengthened for 14.25 mm in average (13.87–14.36 mm). There were no significant differences between simulation distraction and post-operative 3-D measurements (p > 0.05). ConclusionsA new designed distraction device could be used in navigation guided mandibular distraction osteogenesis on goats with high accuracy by using the TBNavis-CMFS navigation system.

An optimal geodetic dynamic reference frame realization for Greece: Methodology and application

On this study the theoretical and practical approach of an optimal geodetic referenceframe realization is described in detail. The Hellenic area due to its strong geodynamic behaviorcreates a rather inhomogeneous velocity field. This issue plays a critical role in stable and longtermgeodetic datum. The methodology of the Minimization of the Kinetic Energy Criterion(MKEC) is defined and analyzed on a permanent GNSS network consisting of 151 stations. Thesites velocities values were estimated from seven years continuously data. The applicationformula shows that the kinematic energy is minimized more than 60 percent in two differentapproaches for the International Terrestrial Reference Frame and the European TerrestrialReference System 1998 (ETRS89). In addition, the realization of the ETRS89 approach in Greeceis not offering any significant advantage. However, we proposed a new strategy, which minimizesthe total kinetic energy and it is found effective in local areas with strong geodynamic activity likethe Greece case.

Interactive navigation-guided ophthalmic plastic surgery: assessment of optical versus electromagnetic modes and role of dynamic reference frame location using navigation-enabled human skulls.

AimThe aim of this study was to assess the anatomical accuracy of navigation technology in localizing defined anatomic landmarks within the orbit with respect to type of technology (optical versus electromagnetic systems) and position of the dynamic reference marker on the skull (vertex, temporal, parietal, and mastoid) using in vitro navigation-enabled human skulls. The role of this model as a possible learning tool for anatomicoradiological correlations was also assessed.MethodsComputed tomography (CT) scans were performed on three cadaveric human skulls using the standard image-guidance acquisition protocols. Thirty-five anatomical landmarks were identified for stereotactic navigation using the image-guided StealthStation S7™ in both electromagnetic and optical modes. Three outcome measures studied were accuracy of anatomical localization and its repeatability, comparisons between the electromagnetic and optical modes in assessing radiological accuracy, and the efficacy of dynamic reference frame (DRF) at different locations on the skull.ResultsThe geometric localization of all the identified anatomical landmarks could be achieved accurately. The Cohen’s kappa agreements between the surgeons were found to be perfect (kappa =0.941) at all predetermined points. There was no difference in anatomical localization between the optical and electromagnetic modes (P≤0.001). Precision for radiological identification did not differ with various positions of the DRF. Skulls with intact anatomical details and careful CT image acquisitions were found to be stereotactically useful.ConclusionAccuracy of anatomic localization within the orbit with navigation technology is equal with optical and electromagnetic system. The location of DRF does not affect the accuracy. Navigation-enabled skull models can be potentially useful as teaching tools for achieving the accurate radiological orientation of orbital and periorbital structures.