A Plant Leaf Geometric Parameter Measurement System Based on the Android Platform.

Automatic and efficient plant leaf geometry parameter measurement offers useful information for plant management. The objective of this study was to develop an efficient and effective leaf geometry parameter measurement system based on the Android phone platform. The Android mobile phone was used to process and measure geometric parameters of the leaf, such as length, width, perimeter, and area. First, initial leaf images were pre-processed by some image algorithms, then distortion calibration was proposed to eliminate image distortion. Next, a method for calculating leaf parameters by using the positive circumscribed rectangle of the leaf as a reference object was proposed to improve the measurement accuracy. The results demonstrated that the test distances from 235 to 260 mm and angles from 0 to 45 degrees had little influence on the leafs' geometric parameters. Both lab and outdoor measurements of leaf parameters showed that the developed method and the standard method were highly correlated. In addition, for the same leaf, the results of different mobile phone measurements were not significantly different. The leaf geometry parameter measurement system based on the Android phone platform used for this study could produce high accuracy measurements for leaf geometry parameters.

Use of a Skin-Fixed Dynamic Reference Frame in Spinal Trauma Surgery: A Case Report.

Intraoperative CT navigation has revolutionized spinal surgery by enhancing precision, particularly in pedicle screw placement. However, the traditional use of bone-fixed dynamic reference frames (DRFs) often necessitates placement on spinous processes, complicating percutaneous pedicle screw (PPS) insertion and requiring additional incisions. This case report presents a novel approach utilizing a skin-fixed DRF in spinal trauma surgery. A 26-year-old female sustained lower limb paralysis, sensory impairment, and bladder-rectal dysfunction after a 15 m fall, resulting in an L1 fracture-dislocation (American Spinal Injury Association score C, Thoracolumbar AOSpine Injury Score score 13). The radiological assessment confirmed dural sac compression. An emergency damage control surgery was conducted using a skin-fixed DRF, secured with sutures and tape near the PPS insertion site. Intraoperative CT navigation guided the insertion of PPS from T11 to L3. The procedure lasted 141 minutes with an estimated blood loss of 256 mL. Postoperative CT verified accurate screw placement. At six months postoperatively, the patient exhibited significant motor recovery and regained independent ambulation. The skin-fixed DRF technique minimizes surgical complexity, obviates the need for additional incisions, and mitigates the challenges associated with bone-fixed DRFs during PPS procedures. This method demonstrates potential as a minimally invasive and effective surgical technique in spinal trauma cases.

Collision avoidance analysis of human-robot physical interaction based on null-space impedance control of a dynamic reference arm plane.

When the terminal upper limb rehabilitation robot is used for motion-assisted training, collisions between the manipulator links and the human upper limb may occur due to the null-space self-motion of the redundant manipulator. A null-space impedance control method based on a dynamic reference arm plane is proposed to realize collision avoidance during human-robot physical interaction motion for the collision problem between the manipulator links and the human upper limb. Firstly, a dynamic model and a Cartesian impedance controller of the manipulator are established. Then, the null-space impedance controller of the redundant manipulator is established based on the dynamic reference plane, which manages the null-space self-motion of the redundant manipulator to prevent collision between the manipulator links and the human upper limb. Finally, it is experimentally verified that the method proposed in this paper can effectively manage the null-space self-motion of the redundant manipulator, and thus achieve collision avoidance during the human-robot physical interaction motion. This research has significant potential in improving the safety and feasibility of motion-assisted training with rehabilitation robots.

Comparative Study on Accuracy of Intra-Operative Computed Tomography-Navigation Based Pedicle Screw Placement With Skin vs Bone Fixed Dynamic Reference Frame in Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To compare the accuracy of intra-operative navigation-assisted percutaneous pedicle screw insertion between bone fixed and skin fixed dynamic reference frame (DRF) in Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). METHODS: Between October 2018 and September 2022, patients who underwent MIS-TLIF were included in this study with DRF fixed either on bone (group B) or skin (group S). Pedicle screws were inserted under the guidance of intra-operative Cone bean Computed tomography (cbCT) based navigation. Accuracy of pedicle screw placement was immediately checked by a final intra-operative cbCT Spin. RESULTS: Among 170 patients, group B included 91 patients and group S included 79 patients. Out of total 680 screws, 364 screws (group B) and 316 screws (group S) were placed. Patient's demographic data and distribution of screws showed no statistically significant difference. The accuracy showed no significant difference between both the groups (94.5% in group B and 94.3% in group S). CONCLUSION: Skin fixed DRF can serve as an alternate way for placement and avoids extra incision with similar accuracy in pedicle screw insertions with bone fixed DRF using intra-operative CT guided navigation in MIS TLIF.

A Timing-Based Split-Path Sensing Circuit for STT-MRAM.

Spin-transfer torque magnetoresistive random access memory (STT-MRAM) applications have received considerable attention as a possible alternative for universal memory applications because they offer a cost advantage comparable to that of a dynamic RAM with fast performance comparable to that of a static RAM, while solving the scaling issues faced by conventional MRAMs. However, owing to the decrease in supply voltage (VDD) and increase in process fluctuations, STT-MRAMs require an advanced sensing circuit (SC) to ensure a sufficient read yield in deep submicron technology. In this study, we propose a timing-based split-path SC (TSSC) that can achieve a greater read yield compared to a conventional split-path SC (SPSC) by employing a timing-based dynamic reference voltage technique to minimize the threshold voltage mismatch effects. Monte Carlo simulation results based on industry-compatible 28-nm model parameters reveal that the proposed TSSC method obtains a 42% higher read access pass yield at a nominal VDD of 1.0 V compared to the SPSC in terms of iso-area and -power, trading off 1.75× sensing time.

Design and operation of a molten salt electrochemical cell.

Molten salts such as 2LiF-BeF2 (FLiBe) have been proposed as coolants for advanced nuclear fission and fusion reactors. Critical to the design, licensing and operation of these reactors is characterization and understanding of the chemical behavior and mass transport of activation and fission products, corrosion products, and other solutes in the coolant. Electrochemical techniques are a powerful suite of tools for probing these phenomena. The design of an experimental cell for molten salt electrochemistry is described herein. As a demonstration of this design, details of the experimental methods used to conduct electrochemical experiments with molten FLiBe with addition of LiH are provided. Decommissioning of the cell is considered from the point of view of decontamination and waste generated. Main features of the cell include:•Suitable for operation up to 800 °C; suitable for operation inside and outside of a glovebox.•Enables sweep gas, gas sampling and analysis; enables addition of solid and liquid materials during operation.•Supports a variety of electrode materials and arrangements.

The endonasal patient reference tracker: a novel solution for accurate noninvasive electromagnetic neuronavigation.

OBJECTIVE: Electromagnetic (EM) navigation provides the advantages of continuous guidance and tip-tracking of instruments. The current solutions for patient reference trackers are suboptimal, as they are either invasively screwed to the bone or less accurate if attached to the skin. The authors present a novel EM reference method with the tracker rigidly but not invasively positioned inside the nasal cavity. METHODS: The nasal tracker (NT) consists of the EM coil array of the AxiEM tracker plugged into a nasal tamponade, which is then inserted into the inferior nasal meatus. Initially, a proof-of-concept study was performed on two cadaveric skull bases. The stability of the NT was assessed in simulated surgical situations, for example, prone, supine, and lateral patient positioning and skin traction. A deviation ≤ 2 mm was judged sufficiently accurate for clinical trial. Thus, a feasibility study was performed in the clinical setting. Positional changes of the NT and a standard skin-adhesive tracker (ST) relative to a ground-truth reference tracker were recorded throughout routine surgical procedures. The accuracy of the NT and ST was compared at different stages of surgery. RESULTS: Ex vivo, the NT proved to be highly stable in all simulated surgical situations (median deviation 0.4 mm, range 0.0-2.0 mm). In 13 routine clinical cases, the NT was significantly more stable than the ST (median deviation at procedure end 1.3 mm, range 0.5-3.0 mm vs 4.0 mm, range 1.2-11.2 mm, p = 0.002). The loss of accuracy of the ST was highest during draping and flap fixation. CONCLUSIONS: Application of the EM endonasal patient tracker was found to be feasible with high procedural stability ex vivo as well as in the clinical setting. This innovation combines the advantages of high precision and noninvasiveness and may, in the future, enhance EM navigation for neurosurgery.

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.

Fusion Image-Guided and Ultrasound-Guided Fine Needle Aspiration in Patients With Suspected Hepatic Metastases.

AIM: The aim of this study was to compare the diagnostic adequacy of computed tomography (CT)-ultrasound (US) fusion image-guided fine needle aspiration (FNA) and US-guided FNA in patients with suspected hepatic metastases. METHODS: Thirty consecutive patients of either sex with known or unknown primary malignancy suspected of having liver metastases on both US and CT, whose multiphasic contrast-enhanced computed tomography was performed using a 64-slice or a higher slice CT scanner, and who were referred for percutaneous FNA were included in this prospective study approved by the institutional review board of the study institute. CT-ultrasound fusion image-guided FNA of the largest lesion using electromagnetic tracking and with freehand ultrasound-guided FNA were performed in the same sitting. Value of fitness, which is a rough estimate of how well the fusion has been achieved, was recorded. Diagnostic adequacy of smears was assessed by a scoring system based on cellular material, background blood/clot, degree of cellular degeneration or trauma, and retention of architecture. RESULTS: The size of the lesions ranged from 1 to 10 cm, and the depth of location of the lesions ranged from 1.4 to 9.3 cm. The fusion fitness values ranged from 1.2 to 10 mm. The scores of the smears did not correlate with lesion size, depth of location, and fusion fitness value. Diagnostic adequacy was seen in 90% and 93.3% of lesions sampled by fusion image guidance and ultrasound guidance, respectively (p = 0.655). All the lesions that yielded inadequate smears by fusion guidance were deep-seated lesions (>5 cm). All the lesions that yielded inadequate smears by ultrasound guidance were small lesions (<3 cm). No complications were encountered in any of the patients. CONCLUSION: Fusion image-guided FNA is a safe procedure with a high diagnostic adequacy rate. Fusion image-guided FNA is not better than US-guided FNA for conspicuous hepatic lesions; however, it may be useful in inconspicuous lesions.

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.

Navigation accuracy comparing non-covered frame and use of plastic sterile drapes to cover the reference frame in 3D acquisition.

BACKGROUND: Advancements in surgical navigation technology coupled with 3-dimensional (3D) radiographic data have significantly enhanced the accuracy and efficiency of spinal fusion implant placement. Increased usage of such technology has led to rising concerns regarding maintenance of the sterile field, as makeshift drape systems are fraught with breaches thus presenting increased risk of surgical site infections (SSIs). A clinical need exists for a sterile draping solution with these techniques. Our objective was to quantify expected accuracy error associated with 2MM and 4MM thickness Sterile-Z Patient Drape® using Medtronic O-Arm® Surgical Imaging with StealthStation® S7® Navigation System. Camera distance to reference frame was investigated for contribution to accuracy error. METHODS: A testing jig was placed on the radiolucent table and the Medtronic passive reference frame was attached to jig. The StealthStation® S7® navigation camera was placed at various distances from testing jig and the geometry error of reference frame was captured for three different drape configurations: no drape, 2MM drape and 4MM drape. The O-Arm® gantry location and StealthStation® S7® camera position was maintained and seven 3D acquisitions for each of drape configurations were measured. Data was analyzed by a two-factor analysis of variance (ANOVA) and Bonferroni comparisons were used to assess the independent effects of camera angle and drape on accuracy error. RESULTS: Median (and maximum) measurement accuracy error was higher for the 2MM than for the 4MM drape for each camera distance. The most extreme error observed (4.6 mm) occurred when using the 2MM and the 'far' camera distance. The 4MM drape was found to induce an accuracy error of 0.11 mm (95% confidence interval, 0.06-0.15; P<0.001) relative to the no drape testing, regardless of camera distance. Medium camera distance produced lower accuracy error than either the close (additional 0.08 mm error; 95% CI, 0-0.15; P=0.035) or far (additional 0.21mm error; 95% CI, 0.13-0.28; P<0.001) camera distances, regardless of whether a drape was used. CONCLUSIONS: In comparison to the 'no drape' condition, the accuracy error of 0.11 mm when using a 4MM film drape is minimal and clinically insignificant.

Novel method for setting up 3D navigation system with skin-fixed dynamic reference frame in anterior cervical surgery.

PURPOSE: To introduce easy and useful methods using 3D navigation system with skin-fixed dynamic reference frame (DRF) in anterior cervical surgery and to validate its accuracy. METHODS: From September 2012 to May 2013, 31 patients underwent anterior cervical surgery and a total of 48 caspar distraction pins were inserted into each cervical vertebra. Every operation was performed using O-arm® navigation system with skin-fixed DRF. To validate the accuracy of these methods, a custom-made metal sleeve was used. In surgical field, through the metal sleeve, the tip of a navigation probe promptly contacts to the tip of caspar pin. We measured the vertical and horizontal distances and the angular deviation in sagittal plane between the caspar pin and the navigation probe on the virtual images and evaluated accuracy of navigation system with skin fixed DRF. RESULTS: Total 31 (males 20, females 11) patients and 48 caspar pins were included in this study. The mean horizontal distance between the caspar pin and the navigation probe displayed in navigation monitor was 0.49 ± 0.71 mm. The mean vertical distance between the caspar pin and the navigation probe displayed in navigation monitor was 0.88 ± 0.93 mm. And the mean angular deviation in sagittal plane between the caspar pin and the navigation probe displayed in navigation monitor was 0.59 ± 0.55°. CONCLUSIONS: 3D navigation system with skin-fixed DRF in anterior cervical surgery is a simple and reliable method and it can be a helpful supplement to a spine surgeon's judgement.