Shift Distance Research Articles

A novel classification of congenital cervicothoracic scoliosis: identification of coronal subtypes and their prognostic significance.

To propose a novel classification system for stratifying coronal curve patterns in congenital cervicothoracic scoliosis with hemivertebrae (CTS-HV). Type A: regional cervicothoracic deformity only disturbing the balance of head-neck-shoulder complex; Type B: cervicothoracic deformity with significant trunk tilt to the convex side; Type C: cervicothoracic deformity with a significant compensatory thoracic curve. The reliability and reproducibility were assessed via the Kappa test. The differences among different subtypes in deformity parameters and bony structures were compared to identify the causative factors predisposing to different subtypes. 98 patients were classified into Type A (47 cases), Type B (31 cases), and Type C (20 cases). The Kappa test showed excellent reliability (Kappa value = 0.847) and reproducibility (Kappa value = 0.881). The proportions of Klippel-Feil syndrome in Types B (71.0%) and C (85.0%) were significantly higher than in Type A (46.8%; all P < 0.05). Type A (66.0%) and Type B (71.0%) predominantly had their hemivertebra (HV) at T3 or T4, while Type C (75%) mostly had HV at T1 or T2. Type B exhibited the most severe trunk tilt, head shift, neck tilt, head tilt, and coronal balance distance (all P < 0.05). Type C had the lowest T1 tilt and first rib angle despite the greatest cervicothoracic Cobb angle (all P < 0.05). This novel reliable classification allows a better understanding of structural diversity and different coronal compensatory mechanisms for the natural progression of CTS-HV. It can contribute to determining the individualized treatment strategy and standardizing academic communication for this rare clinical entity.

Advancing continual lifelong learning in neural information retrieval: Definition, dataset, framework, and empirical evaluation

Continual learning refers to the capability of a machine learning model to learn and adapt to new information, without compromising its performance on previously learned tasks. Although several studies have investigated continual learning methods for neural information retrieval (NIR) tasks, a well-defined task definition is still lacking, and it is unclear how typical learning strategies perform in this context. To address this challenge, a systematic task definition of continual NIR is presented, along with a multiple-topic dataset that simulates continuous information retrieval. A comprehensive continual neural information retrieval framework consisting of typical retrieval models and continual learning strategies is then proposed. Empirical evaluations illustrate that the proposed framework can successfully prevent catastrophic forgetting in neural information retrieval and enhance performance on previously learned tasks. The results also indicate that embedding-based retrieval models experience a decline in their continual learning performance as the topic shift distance and dataset volume of new tasks increase. In contrast, pretraining-based models do not show any such correlation. Adopting suitable learning strategies can mitigate the effects of topic shift and data augmentation in continual neural information retrieval.

Arthroscopic medial patellofemoral ligament reconstruction with polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients with a follow-up of at least 2 years

PurposeThe purpose of this study was to propose a surgical technique for arthroscopic medial patellofemoral ligament (MPFL) reconstruction with polyethylene suture combined with medial retinaculum plication and to evaluate the efficacy of this surgical technique in the treatment of acute patellar dislocation.MethodsClinical data of patients with acute patellar dislocations treated with arthroscopic MPFL reconstruction with polyethylene tape (FiberTape) combined with medial support band compression were analyzed retrospectively from January 2018 to January 2021. The mean age of the patients was 25.15 ± 4.66 years; the mean follow-up time was 27.5 (24–36) months. Clinical evaluation consisted of apprehension test results, patellar extrapolation test results, Lysholm score, Kujala score, and IKDC score, the Patellar lateral shift distance and patellar tilt angle (PTA) measured by CT scan.ResultsAll patients had no recurrent patellar dislocation or subluxation after surgery, and the apprehension test was negative. In all patients, the Kujala score (36.0 ± 9.9 vs. 98.2 ± 3.1), the IKDC score (48.6 ± 7.0 vs. 90.6 ± 4.4) and the Lysholm score (32.8 ± 10.4 vs. 96.7 ± 3.1) had improved at the 24-month follow up (P < 0.05). In addition, PTA was significantly lower at the 12-month follow-up and 24-giving-month follow-up compared to the preoperative period (P < 0.05, Table 2). The patellar lateral shift distance decreased from 14.94 ± 6.11 mm preoperatively to 3.00 ± 1.40 mm (12-month follow up) and 3.26 ± 1.37 mm (24-month follow up), respectively.ConclusionArthroscopic MPFL reconstruction with polyethylene suture combined with medial retinaculum plication is a safe and reliable surgical technique for the treatment of acute patellar dislocation in young and middle-aged patients.Level of EvidenceLevel III, Therapeutic Study.

The Effect of Model Input Uncertainty on the Simulation of Typical Pollutant Transport in the Coastal Waters of China

Route planning to evade potential pollution holds critical importance for aquaculture vessels. This study establishes a fish-feed pollutant drift model based on the Lagrangian particle tracking algorithm and designs four sets of sensitivity experiments in the East China Sea. The research investigates the impact of model input uncertainties on the drift trajectory, centroid position, and sweeping area of the fish-feed pollutants. Numerical results indicate that the uncertainty in the background flow field significantly affects the uncertainty in the centroid position and sweeping area in the numerical simulations. Specifically, when a 35% random error is added to the background flow field, the centroid shift distance reaches its maximum, and the sweeping area also attains its largest value. The uncertainty in the background wind field affects the centroid position of particles but to a much lesser extent compared to the background flow field. When considering only the uncertainty of the background wind field, the sweeping area does not significantly differ from the control experiment as the uncertainty of the background wind field increases. The initial release position has little effect on the drift direction of the fish-feed pollutants but does affect the drift distance; it has minimal impact on the trajectory but significantly affects the final position of the pollutant centroid. By analyzing the model uncertainties, this study reveals the key factors influencing the drift of fish-feed pollutants. This information is crucial for aquaculture vessels in planning routes, considering environmental factors, and reducing potential pollution risks.

Dynamic and structural analyses of floating dock operations considering dock-vessel coupling loads

Floating docks are important for increasing the capacity of land-based shipyards and serve as essential platforms for vessel construction, maintenance, and repair. As the size of modern vessels increases, ensuring the structural safety of the floating docks becomes challenging. To enhance the operational safety of the floating docks, this study aims to develop an in-house code for a comprehensive global response assessment of a full-scale floating dock. The code is developed under a quasi-static assumption and enables dynamic and structural response assessments for the floating dock and docked vessel during the vessel-docking operations. The floating dock and docked vessel are represented as rigid bodies with six degrees of freedom and subjected to hydrostatic, hydrodynamic, mooring, and contact loads. The piping network of the floating dock's ballast water system is modelled to calculate the flow rates out of all ballast tanks. A modified proportional controller (P-controller) is employed to achieve automatic ballast control, regulating opening angles of ballast tank valves to minimize roll and pitch motions of the floating dock and docked vessel. For structural response assessment, a bending model is proposed to evaluate the bending deformation of the floating dock based on the load distribution along the dock's length. Results show that the present code can successfully simulate the vessel-docking process. The automatic ballast control strategy effectively minimizes roll and pitch for both the floating dock and docked vessel, ensuring stable control of the entire system. Minimal discrepancies are observed in the dynamic responses and bending of the floating dock between one- and two-way couplings. The longitudinal shift of the docked vessel's centre of gravity (CoG) increases the relative motions between the docked vessel and the floating dock, especially in surge, sway and pitch. A significant shift distance might cause the mooring rope breakage. Positioning the vessel's CoG closer to the dock's CoG proves safer for vessel-docking operations. In general, the developed code can support the decision-making for dock masters and optimize the docking plan.

Investigations of structural, photoluminescence, colorimetric, lifetime, and luminous efficiency of Tb3+ and Sm3+ co-doped calcium tungstate for WLEDs

Structure, photoluminescence, colorimetric, and thermoluminescence analysis of Ca1-x-yTb2x/3Sm2y/3WO4; x = 0.01; y = 0.01–0.05 ceramics are reported in this manuscript. The materials are made by the use of the solid-state method. Reitveld refinements of the obtained X-ray diffraction patterns are done by using the Fullprof Suite software. The obtained results denoted that the synthesized materials have a tetragonal structure and I41/a space group. Energy bandgaps are found in the UV–visible absorbance spectra. Photoluminescence investigations of the phosphors are done. The critical quenching concentrations of the phosphor are found to be x = 0.01; and y = 0.04. Moreover, the critical distance of energy shift with the adjacently presented ions is computed. Dexter’s theory is employed to elucidate that the dipole-dipole electronic interactions are the imperative reasons for the transfer of energy in the phosphor. The white color of emission is achieved for x = 0.01, y = 0.04 Tb, and Sm doped CaWO4 material. Moreover, great values in color purity, correlated color temperature, color rendering index as well as luminous efficiency of radiation are obtained from the CIE Chromaticity coordinates. Quantum yield efficiency of x = 0.01, y = 0.04 Tb & Sm codoped CaWO4 is measured. Photoluminescence decay analysis of all the samples is done to study the long-after glow properties and also the average lifetime values are evaluated. This is an indication of the suitable usage of the prepared materials in the white light-emitting diodes. Concentration as well as dose-dependent Thermoluminescence spectroscopy is investigated thoroughly. Kinetic parameters are calculated by deconvoluting the spectra of x = 0.01; y = 0.01 Tb & Sm codoped CaWO4 irradiated with 15 min of UV excitation dose. These results are denoted by high trap depth, second-order kinetics, and low UV dosimetry of the phosphor.

Transition from anisotropic to isotropic optical absorption in core-shell square nanowires tuned by anti-crossing engineering.

The transition from anisotropic to isotropic optical properties in nanostructures plays an important role in developing next-generation intelligent photonic devices. Currently, core-shell nanostructures, frequently accompanied by different growth rates, are typically characterized by anisotropic optical properties at mid-infrared wavelengths. This inherent anisotropy, however, poses formidable challenges in achieving optical isotropy. In this work, an electric field is employed to transform the optical anisotropy of the off-centered core-shell square nanowires into optical isotropy. Based on the finite difference method, the results show that by tuning the electric field reasonably, the anti-crossing behavior of energy levels can be induced to align the energy structures in both eccentric and concentric nanowires. Although the optical anisotropy is strongly dependent on the distance and direction of the core shift, we marks, to the best of our knowledge, the first demonstration that the restored electronic states can effectively neutralize the polarization sensitivity, achieving isotropic optical absorption with wavelengths longer than 10 μm. Our finding indicates that the anti-crossing behavior of energy levels can serve as a viable mechanism to achieve switchable optical isotropy.

Roles of Thermal Forced and Eddy‐Driven Effects in the Northward Shifting of the Subtropical Westerly Jet Under Recent Climate Change

AbstractThe zonal‐mean subtropical westerly jet (SWJ) in boreal winter shows a significant northward shift trend under recent climate change. Previous studies proposed thermal forcing—represented by the thermal wind associated with the temperature gradient—and the driving effect of the eddy momentum flux (EMF) convergence that leads to the eddy‐driven jet as explanations for this process; however, their relative importance in influencing the SWJ shift requires further investigation. In this study, we examined the roles of thermal forced and eddy‐driven jet components in the zonal‐mean northward SWJ shift. We also investigated the role of Hadley circulation because its poleward boundary is related to the zonal‐mean SWJ. Results suggest that thermal forced component plays a major role, while EMF‐driven component plays a secondary role. Specifically, the subtropical warming, which is primarily influenced by enhanced adiabatic downward motion of the Hadley circulation, increases the meridional temperature gradient and the associated thermal wind poleward of the SWJ. It also reduces atmospheric static stability aloft and converges the EMF on the poleward side of the climatological SWJ. Enhanced meridional temperature gradient and EMF convergence on the poleward side push the SWJ northward. Results from further mathematical analysis indicate that thermal forced and eddy‐driven zonal wind components account for 72% and 28% of the shift distance, respectively. In addition to elucidating the relative importance of thermal and EMF forcings, this study emphasizes the critical role of the subtropical warming driven by the intensified local descending branch of the Hadley circulation in shifting the zonal‐mean SWJ.

Relocation of the Hypocenter of an Earthquake with the Double Difference Method in the Regional Study Area of Yogyakarta

The relocation of the earthquake hypocentre is necessary in order to determine the position of the earthquake centre with higher accuracy. An accurate hypocentre position is important for earthquake-prone areas mapping, seismicity analysis, and fault zone identification. The double difference algorithm technique using the hypoDD program can be used for hypocentre relocation. This article reports the earthquake relocation of 23 earthquakes in the Yogyakarta region recorded at four observation stations. The result shows that the hypocentre shift spreads randomly with a shift distance of less than 20 km, with the most shifting direction of the epicentre to the northeast. The Earthquake’s hypocentre after relocation in the land area is estimated to be triggered by a fault under the Gamping Wungkal Formation, while the earthquake around Mount Merapi is estimated to be triggered by volcanic activity. The Relocation result in the sea area show that the hypocentre leads to the subduction line.

A scintillation dosimeter with real-time positional tracking information for in vivo dosimetry error detection in HDR brachytherapy.

To evaluate the performance of an electromagnetic (EM)-tracked scintillation dosimeter in detecting source positional errors of IVD in HDR brachytherapy treatment. Two different scintillator dosimeter prototypes were coupled to 5 degrees-of-freedom (DOF) EM sensors read by an Aurora V3 system. The scintillators used were a 0.3 × 0.4 × 0.4 mm3 ZnSe:O and a BCF-60 plastic scintillator of 0.5 mm diameter and 2.0 mm in length (Saint-Gobain Crystals). The sensors were placed at the dosimeter's tip at 20.0 mm from the scintillator. The EM sampling rate was 40/s while the scintillator signal was sampled at 100 000/s using two photomultiplier tubes from Hamamatsu (series H10722) connected to a data acquisition board. A high-pass filter and a low-pass filter were used to separate the light signal into two different channels. All measurements were performed with an afterloader unit (Flexitron-Elekta AB, Sweden) in full-scattered (TG43) conditions. EM tracking was further used to provide distance/angle-dependent energy correction for the ZnSe:O inorganic scintillator. For the error detection part, lateral shifts of 0.5 to 3 mm were induced by moving the source away from its planned position. Indexer length (longitudinal) errors between 0.5 to 10 mm were also introduced. The measured dose rate difference was converted to a shift distance, with and without using the positional information from the EMsensor. The inorganic scintillator had both a signal-to-noise-ratio (SNR) and signal-to-background-ratio (SBR) close to 70 times higher than those of the plastic scintillator. The mean absolute difference from the dose measurement to the dose calculated with TG-43U1 was 1.5% ±0.7%. The mean absolute error for BCF-60 detector was 1.7% when compared to TG-43 calculations formalism. With the inorganic scintillator and EM tracking, a maximum area under the curve (AUC) gain of 24.0% was obtained for a 0.5-mm lateral shift when using the EMT data with the ZnSe:O. Lower AUC gains were obtained for a 3-mm lateral shifts with both scintillators. For the plastic scintillator, the highest gain from using EM tracking information occurred for a 0.5-mm lateral shift at 20 mm from the source. The maximal gain (17.4%) for longitudinal errors was found at the smallest shifts (0.5 mm). This work demonstrates that integrating EM tracking to in vivo scintillation dosimeters enables the detection of smaller shifts, by decreasing the dosimeter positioning uncertainty. It also serves to perform position-dependent energy correction for the inorganic scintillator,providing better SNR and SBR, allowing detection of errors at greater distances from thesource.

DSMRI: Domain Shift Analyzer for Multi-Center MRI Datasets.

In medical research and clinical applications, the utilization of MRI datasets from multiple centers has become increasingly prevalent. However, inherent variability between these centers presents challenges due to domain shift, which can impact the quality and reliability of the analysis. Regrettably, the absence of adequate tools for domain shift analysis hinders the development and validation of domain adaptation and harmonization techniques. To address this issue, this paper presents a novel Domain Shift analyzer for MRI (DSMRI) framework designed explicitly for domain shift analysis in multi-center MRI datasets. The proposed model assesses the degree of domain shift within an MRI dataset by leveraging various MRI-quality-related metrics derived from the spatial domain. DSMRI also incorporates features from the frequency domain to capture low- and high-frequency information about the image. It further includes the wavelet domain features by effectively measuring the sparsity and energy present in the wavelet coefficients. Furthermore, DSMRI introduces several texture features, thereby enhancing the robustness of the domain shift analysis process. The proposed framework includes visualization techniques such as t-SNE and UMAP to demonstrate that similar data are grouped closely while dissimilar data are in separate clusters. Additionally, quantitative analysis is used to measure the domain shift distance, domain classification accuracy, and the ranking of significant features. The effectiveness of the proposed approach is demonstrated using experimental evaluations on seven large-scale multi-site neuroimaging datasets.

Femoral neck version in the spinopelvic and lower limb 3D alignment: a full-body EOS® study in 400 healthy subjects.

The goal of this study was to better understand the variation of femoral neck version according to spinopelvic and lower limb 3D alignment using biplanar X-rays in standing position. This multicentric study retrospectively included healthy subjects from previous studies who had free-standing position biplanar radiographs. Subjects were excluded if they presented spinal or any musculo-skeletal deformity, and reported pain in the spine, hip or knee. Age, sex, and the following 3D-reconstructed parameters were collected: spinal curvatures, pelvic parameters, sagittal vertical axis (SVA), T1 pelvic angle (TPA), spino-sacral angle (SSA), femoral torsion angle (FTA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle angle (AA), pelvic shift (PS) and ankle distance. Femoral neck version angle (FVA) was calculated between horizontal plane projection of the bi-coxo-femoral axis and the line passing through the femoral neck barycenter and femoral head center. Analysis according to age subsets was performed. A total of 400 subjects were included (219 females); mean age was 29 ± 18years (range: 4-83). Subjects with high pelvic tilt values presented significantly higher FVA than average and low-PT individuals, respectively, 7.8 ± 7.1°, 2 ± 9° and 2.1 ± 9.5° (p < 0.001). These subjects also presented lower lumbar lordosis values and higher acetabulum anteversion in the horizontal plane than the two other groups. SVA correlation with FVA was weaker (r = 0.1, p = 0.03) than SSA and TPA (r = - 0.3 and r = 0.3, respectively, p < 0.001). A strong correlation was found with femoral torsion (r = 0.5, p < 0.001). SFA (r = - 0.3, p < 0.001), pelvic shift (r = 0.2, p < 0.001) and ankle distance (r = 0.3, p < 0.001) were also significantly correlated. Multivariate analysis confirmed significant association of age, pelvic tilt, lumbar lordosis, pelvic shift, ankle distance and femoral torsion with FVA. Patients with lower lumbar lordosis present pelvic retroversion which induces a higher femoral neck version. This finding may help positioning implants in total hip replacement procedures. Higher pelvic shift, age, male gender and increased femoral torsion were also correlated with higher FVA. II (Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding).

Tunable atom lithography scheme with high resolution in atomic system

We theoretically propose a scheme that utilizes the excited state of a Λ-type three-level atom system for atom lithography. A standing-wave coupling field and a probe field provide localized probability distribution of the excited atoms. Unlike the previous studies in atom localization, we focus on splitting the single-peak structure localized on the node of the standing-wave field to a double-peak structure. The shift distance of double-peak related to the parameters of external laser fields is investigated. The period of lithography pattern could reach λ/4, while the resolution of lithography is promising to be smaller than 0.02λ by adjusting system parameters. This scheme can be extended to form a two-dimensional pattern for lithography.

Does a negative correlation of heme oxygenase-1 with hematoma thickness in chronic subdural hematomas affect neovascularization and microvascular leakage? A retrospective study with preliminary validation.

Chronic subdural hematoma (CSDH) is a common neurological disease among elderly adults. The progression of CSDH is an angiogenic process, involving inflammatory mediators that affect vascular permeability, microvascular leakage, and hematoma thickness. The authors aimed to identify biomarkers associated with angiogenesis and vascular permeability that might influence midline shift and hematoma thickness. Medical records and laboratory data of consecutive patients who underwent surgery for CSDH were analyzed. Collected data were basic demographic data, CSDH classification, CSDH thickness, midline shift, heme oxygenase-1 (HO-1) levels in hematomas, and common laboratory markers. Linear regression analysis was used to evaluate the relationship of CSDH thickness with characteristic variables. The chick chorioallantoic membrane (CAM) assay was used to test the angiogenic potency of identified variables in ex ovo culture of chick embryos. In total, 93 patients with CSDH (71.0% male) with a mean age of 71.0 years were included. The mean CSDH thickness and midline shift were 19.7 and 9.8 mm, respectively. The mean levels of HO-1, ferritin, total bilirubin, white blood cells, segmented neutrophils, lymphocytes, platelets, international normalized ratio, and partial thromboplastin time were 36 ng/mL, 14.8 μg/mL, 10.5 mg/dL, 10.3 × 103 cells/μL, 69%, 21.7%, 221.1 × 109 cells/μL, 1.0, and 27.8 seconds, respectively. Pearson correlation analysis revealed that CSDH thickness was positively correlated with midline shift distance (r = 0.218, p < 0.05) but negatively correlated with HO-1 concentration (r = -0.364, p < 0.01) and ferritin level (r = -0.222, p < 0.05). Multivariate linear regression analysis revealed that HO-1 was an independent predictor of CSDH thickness (β = -0.084, p = 0.006). The angiogenic potency of HO-1 in hematoma fluid was tested with the chick CAM assay; topical addition of CSDH fluid with low HO-1 levels promoted neovascularization and microvascular leakage. Addition of HO-1 in a rescue experiment inhibited CSDH fluid-mediated angiogenesis and microvascular leakage. HO-1 is an independent risk factor in CSDH hematomas and is negatively correlated with CSDH thickness. HO-1 may play a role in the pathophysiology and development of CSDH, possibly by preventing neovascularization and reducing capillary fragility and hyperpermeability.

A novel objective method for discriminating pathological and physiological colorectal uptake in the lower abdominal region using whole-body dynamic 18F-FDG-PET.

To investigate whether the center-of-mass shift distance (CMSD) analysis on whole-body dynamic positron emission tomography (WBD-PET) with continuous bed motion is an objective index for discriminating pathological and physiological uptake in the lower abdominal colon. We retrospectively analyzed the CMSD in 39 patients who underwent delayed imaging to detect incidental focal uptake that was difficult to determine as pathological and physiological on a conventional early-PET (early) image reconstructed by 5-phase WBD-PET images. The CMSD between each phase of WBD-PET images and between conventional early and delayed (two-phase) PET images were classified into pathological and physiological uptake groups based on endoscopic histology or other imaging diagnostics. The diagnostic performance of CMSD analysis on WBD-PET images was evaluated by receiver operator characteristic (ROC) analysis and compared to that of two-phase PET images. A total of 66 incidental focal uptake detected early image were classified into 19 and 47 pathological and physiological uptake groups, respectively. The CMSD on WBD-PET and two-phase PET images in the pathological uptake group was significantly lower than that in the physiological uptake group (p < 0.01), respectively. The sensitivity, specificity, and accuracy in CMSD analysis on WBD-PET images at the optimal cutoff of 5.2mm estimated by the Youden index were 94.7%, 89.4%, and 89.4%, respectively, which were not significantly different (p = 0.74) from those of two-phase PET images. The CMSD analysis on WBD-PET was useful in discriminating pathological and physiological colorectal uptake in the lower abdominal region, and its diagnostic performance was comparable to that of two-phase PET images. We suggested that CMSD analysis on WBD-PET images would be a novel objective method to omit unnecessary additional delayed imaging.

Federated Learning for IoT Devices With Domain Generalization

Federated Learning (FL) is a distributed machine learning technique that allows numerous Internet of Things (IoT) devices to jointly train a machine learning model using a centralized server for help. Local data never leaves each IoT device in FL, so the local data of IoT devices are protected. In FL, distributed IoT devices usually collect their local data independently, so the dataset of each IoT device may naturally form a distinct source domain. In real-world applications, the model trained over multi-source domains may have poor generalization performance on unseen target domains. To address this issue, we propose FedADG to equip federated learning with domain generalization capability. FedADG employs the federated adversarial learning approach to measure and align the distributions among different source domains via matching each distribution to a reference distribution. The reference distribution is adaptively generated (by accommodating all source domains) to minimize the domain shift distance during alignment. Therefore, the learned feature representation tends to be universal, and thus, it has good generalization performance over the unseen target domains while protecting local data privacy. Intensive experiments on various datasets demonstrate that FedADG has comparable performance with the state-of-the-art.

Relationship Between the Number of Hip Abduction Performance With Contralateral Adduction in Side-lying and the Lateral Pelvic Shift Distance During One-leg Lifting

Relationship Between the Number of Hip Abduction Performance With Contralateral Adduction in Side-lying and the Lateral Pelvic Shift Distance During One-leg Lifting

Influence of different factors on registration error in a 1.5 T MR-guided linac

Purpose. Accurate image registration is an important step in online image-guided adaptive radiotherapy. The aim of this study was to investigate the effects of different factors on registration accuracy in a magnetic resonance (MR)-guided adaptive radiotherapy workflow. Materials and Methods. A thorax motion phantom was used to obtain computed tomography (CT) simulations in 8 different motion modes and to generate 8 reference plans. Daily pretreatment online MR images were obtained at 5 different positions in each reference plan. Online MR and CT simulations were separately registered using bone structures and the gross tumor volume (GTV) as ROIs, and the image shift distance was recorded by the online treatment planning system. The difference between the shift distance and the real isocentric distance was the registration error. The registration error was analyzed, and the effects of the setup position, motion mode and ROI selection on the registration error were investigated by multivariate analysis of variance. Result. The minimum values of registration error (ΔX, ΔY, ΔZ) were −1.90 mm, −2.70 mm and −2.40 mm, respectively, and the maximum values were 1.70 mm, 4.30 mm and −0.90 mm. ΔY showed the maximum mean standard deviation of 1.25 mm, and ΔZ showed the minimum mean standard deviation of 0.27 mm. The standard deviation of the registration error is largest in the inferior/superior direction. The motion mode of the phantom and ROI selection were significantly correlated with ΔX, ΔY, and ΔZ (p < 0.05). Conclusion. The registration result with the spine as the selected ROI was better than that with the GTV as the ROI. In 1.5 T MR-linac clinical treatment, more attention should be given to patient movement repeatability and to controlling the intrafractional motion as much as possible. It is not recommended to make the GTV-PTV margin expansion less than 2 mm for MR-linac.

Quantification of carpal tunnel morphology using centroid-to-boundary distance shape signatures.

Morphology analysis is valuable to understanding risk factors and the etiology of carpal tunnel (CT) syndrome. The objective of this study was to investigate morphology changes along the length of the CT using shape signatures (SS). Analysis was performed on ten cadaveric specimens in neutral wrist posture. Centroid-to-boundary distance SS were generated for proximal, middle, and distal CT cross-sections. Phase shift and Euclidean distance were quantified relative to a template SS for each specimen. Medial, lateral, palmar, and dorsal peaks were identified on each SS to generate metrics of tunnel width, tunnel depth, peak amplitude, peak angle. Width and depth measures were also performed using previously reported methods to serve as a basis of comparison. The phase shift revealed twisting of 21° between the ends of the tunnel. Distance from the template and width varied significantly over the length of the tunnel, while depth did not. Measures of width and depth using the SS method were consistent with previously reported methods. The SS method afforded the advantage of peak analysis with overall trends of peak amplitude indicating flattening of the tunnel at the proximal and distal ends relative to a rounder shape in the middle.

Electrode Tip Shift During the Stereotactic Electroencephalography Evaluation Period with Boltless Suture Fixation

Electrodes for stereotactic electroencephalography (SEEG) are typically fixed to the skull with anchor bolts. When anchor bolts are unavailable, electrodes have to be fixed using other methods, carrying the possibility of electrode shift. This study, therefore, evaluated the characteristics of electrode tip shift during SEEG monitoring in patients with electrodes fixed using the suture technique. We retrospectively included patients who underwent SEEG implantation with suture fixation and evaluated the tip shift distance (TSD) of electrodes. Possible influences evaluated included: 1) implantation period, 2) lobe of entry, 3) unilateral or bilateral implantation, 4) electrode length, 5) skull thickness, and 6) scalp thickness difference. A total of 50 electrodes in 7 patients were evaluated. TSD was 1.4±2.0mm (mean±standard deviation). Implantation period was 8.1±2.2days. Entry lobe was frontal for 28 electrodes and temporal for 22 electrodes. Implantation was bilateral for 25 electrodes and unilateral for 25 electrodes. Electrode length was 45.4±14.3mm. Skull thickness was 6.0±3.7mm. Scalp thickness difference was-1.5±2.1mm, which was found greater in temporal lobe entry compared with frontal lobe entry. According to univariate analyses, neither implantation period nor electrode length correlated with TSD. Multivariate regression analysis showed that only greater scalp thickness difference correlated significantly with greater TSD (P=0.0018). Greater scalp thickness difference correlated with greater TSD. Surgeons need to consider the degree of scalp thickness difference and electrode shift when using suture fixation, especially with temporal lobe entry.