Projection Angle Research Articles

Comparison of hip abductors’ strength and 2D frontal plane projection angle during two functional tests, in females with and without patellofemoral pain

IntroductionHip abductors eccentrically maintain leg alignment during weight-bearing exercises. Hip abductors' weakness may be a significant aspect to take into account in the conservative management of Patellofemoral Pain (PFP). The aim of the study was to compare hip abductors’ eccentric strength and hip kinematics during two functional tests, in female subjects with PFP. MethodIn a cross-sectional study using convenience sampling, isokinetic Isokinetic unilateral eccentric hip abductors’ mean peak moment (MPM) at 60°/sec and Frontal Plane Projection Angle (FPPA) during Single-Leg Squat (SLS) and Single-Leg Landing (SLL) tests, were assessed in 17 asymptomatic individuals and 19 PFP patients. ResultsThe FPPA during SLL (p = 0.771) and SLS (p = 0.587), as well as the isokinetic values of the eccentric adductors' MPM at 60°/sec (p = 0.769), did not differ between the groups. The isokinetic values and the SLL (r = −0.009 to p = 0.970) and SLS (r = −0.002 to p = 0.993) in the PFP group and the control group (SLS r = 0.160 to p = 0.540) did not show any statistically significant relationships. ConclusionPFP and asymmetry in hip abduction strength are not substantially correlated. It is necessary to conduct more research to comprehend how these impairments interact and to find out if there are patient subgroups with PFP.

Correlation between frontal plane projection angle and pain, dynamic balance and function in patients with patellofemoral pain syndrome

Correlation between frontal plane projection angle and pain, dynamic balance and function in patients with patellofemoral pain syndrome

Relationship between scapular body morphology and rotator cuff tears: a threedimensional computed tomography study.

The purpose of this study was to identify the relationship between scapula morphology and rotator cuff tears (RCT). Hundred seventeen shoulders with and 87 shoulders without RCTs were included in this retrospective study. The critical shoulder angle (CSA) and lateral acromion angle in the coronal view, and the acromial coverage angle (ACA) and coracoid and scapular spine angle (CSSA) in the sagittal view were evaluated using 3-dimensional computed tomography. The glenoid anterior tilt, anterior acromial projection angle (AAPA), coracoid process angle, scapular spine angle (SSA), and inferior angle angle (IAA) with respect to the scapular plane were measured in the sagittal view. In univariate logistic regression analysis, CSA, ACA, AAPA, SSA, and IAA were significantly greater in shoulders with RCTs, whereas CSSA was greater in shoulders without RCTs. In multivariate logistic regression analysis, CSA and IAA were greater in shoulders with RCT and were significantly associated with this condition (P=.00073, P=.0032). This study has shown us that RCTs were associated with a greater curvature of the scapular body and greater CSA and IAA.

Cervical Spondylosis Diagnosis Based on Convolutional Neural Network with X-ray Images.

The increase in Cervical Spondylosis cases and the expansion of the affected demographic to younger patients have escalated the demand for X-ray screening. Challenges include variability in imaging technology, differences in equipment specifications, and the diverse experience levels of clinicians, which collectively hinder diagnostic accuracy. In response, a deep learning approach utilizing a ResNet-34 convolutional neural network has been developed. This model, trained on a comprehensive dataset of 1235 cervical spine X-ray images representing a wide range of projection angles, aims to mitigate these issues by providing a robust tool for diagnosis. Validation of the model was performed on an independent set of 136 X-ray images, also varied in projection angles, to ensure its efficacy across diverse clinical scenarios. The model achieved a classification accuracy of 89.7%, significantly outperforming the traditional manual diagnostic approach, which has an accuracy of 68.3%. This advancement demonstrates the viability of deep learning models to not only complement but enhance the diagnostic capabilities of clinicians in identifying Cervical Spondylosis, offering a promising avenue for improving diagnostic accuracy and efficiency in clinical settings.

Females Present Different Single-Leg Squat Kinematics and Muscle Activation Strategies than Males Even after Hip Abductor Fatigue

Background: Despite the potential connection between hip and knee muscle control, there is limited research on the effects of hip abductor fatigue on the hip and knee neuromuscular responses in both males and females. This study aimed to investigate the influence of sex on the hip and knee frontal plane kinematics and the EMG responses of the hip abductors and knee extensor muscles during the single-leg squat before and after hip abductor fatigue. Methods: A total of 30 participants (males, n = 15; females, n = 15) performed single-leg squats before and immediately after a hip abductor fatigue protocol (10° hip abduction position while bearing a 20% load of their estimated 1RM until exhaustion). The frontal plane kinematics (hip adduction and knee frontal plane projection angle) and EMG parameters (amplitude and median frequency) of the gluteus medius (GMed), tensor fascia latae (TFL), vastus lateralis (VL) and vastus medialis (VM) were measured during the single-leg squat. Results: We did not find any effects of hip abductor fatigue or interaction between fatigue and sex on the evaluated parameters (p > 0.05). However, compared to males, females had greater values for the hip and knee frontal plane kinematics (p = 0.030), GMed EMG amplitude (+10.2%, p = 0.012) and median frequency (+10.3%; p = 0.042) and lower VL median frequency (−9.80%; p = 0.007). Conclusions: These findings establish sex-related differences in the kinematics and hip and knee EMG parameters during the single-leg squat, which were not influenced by the hip abductor fatigue protocol.

Kinematics of 90° change of direction in young football players: Insights for ACL injury prevention from the CUTtheACLstudy on 6008 trials.

To investigate the 90° change of direction (COD) task in an extensive cohort of competitive healthy football players within the CUTtheACLstudy and to provide normative values and differences between males and females for full-body kinematics based on two-dimensional (2D) video analysis and scoring system. One-thousand-and-two competitive football (soccer) players (age 16.3 ± 2.8 years, 264 females) were prospectively enroled. Each player performed three preplanned 90° COD tasks per limb. The 2D evaluation was performed through objective measures (collected through three high-speed cameras) of frontal and sagittal plane joint kinematics at the cut initial foot contact (IC) and maximum knee flexion angle. A previously published scoring system was adopted to measure the movement quality of the COD task. The scoring system included five criteria (limb stability [LS], pelvis stability [PS], trunk stability [TS], shock absorption [SA], movement strategy [MS]) ranked from 0/2 (nonadequate) to 2/2 (adequate) with a maximum score of 10/10. Normative data were provided for all the variables; statistical differences between male and female players were investigated (p < 0.05). A total of 6008 valid attempts were included. Frontal plane knee projection angle (FPKPA) at initial contact was 24.4 ± 9.8° (95thpercentile: FPKPA > 40°). The total score was ≤4/10 in 71.2% of the trials, the lowest subscores were LS and PS. Female players showed different movement patterns with lower hip and trunk flexion both at IC and maximum knee flexion angle (p < 0.01, ES = 0.41-0.64). Female players also showed worse scores than males in SA, MSand total score (p < 0.01). Female players seem more prone to stiffer lower limb strategy and greater pelvis-trunk frontal plane instability than males. Clinicians could adopt normative data and sex-specific differences in players' movement techniques to improve ACL injury risk mitigation protocols. Level IV.

Effect of scan body designs and internal conical angles on the 3-dimensional accuracy of implant digital scans

Statement of problemAxial displacement is inevitable when connecting scan bodies to implants for digital scans using intraoral scanners, and axial displacement may reduce implant position accuracy in digital casts. However, studies assessing scan body type and accuracy are lacking. PurposeThe purpose of this in vitro study was to assess the linear and angular displacements of implants in digital casts using 2 scan body types with or without a vertical stop to minimize the axial displacement and 2 internal conical connection implants (ICCIs) with different internal conical angles. Material and methodsTwo identical reference casts were fabricated from epoxy resin by duplicating a partially edentulous mandibular dentiform. Each cast received 3 implants in the left first premolar, first molar, and second molar regions. One cast received an ICCI with a 7-degree internal conical angle (7-degree ICCI), and the other received an ICCI with an 11-degree internal conical angle (11-degree ICCI). A 10-mm polyetheretherketone (PEEK) cube was attached to the buccal area of the mandibular second premolar of each reference cast. A vertical stop was used in the experimental scan bodies to minimize the axial displacement, and conventional scan bodies were hand tightened to the implants in the reference casts. An intraoral scanner was used to fabricate 4 digital cast groups (2 implant types and 2 scan body types; each group had 10 casts). A coordinate measuring machine and digital inspection software program were used to measure the implant platform centroids (x, y, z) and projection angles (θXY, θYZ, θZX) of implant long axes in the reference and digital casts, respectively. One-way analysis of variance (ANOVA) and linear mixed model both with Tukey post hoc and 2-way ANOVA tests were performed to assess the significance of linear and angular displacements between groups (α=.05). ResultsSignificant differences were noted in all linear displacement variables among the 4 digital cast groups, except for Δx in the left first premolar implant. For the 7-degree ICCI, the linear displacement was statistically similar in the experimental and conventional scan bodies. However, for the 11-degree ICCIs, the experimental scan body group resulted in significantly smaller Δy, Δz, and Δd (Δd2=Δx2+Δy2+Δz2) than the conventional scan body group (P<.05). Overall, the 11-degree ICCIs demonstrated a significantly greater linear displacement than the 7-degree ICCI, regardless of the scan body type (P<.05). Significant differences between the test groups were observed for 10 of the 12 angular displacement variables (P<.05). ConclusionsThe 11-degree ICCIs demonstrated significantly greater linear displacements in Δy, Δz, and Δr than the 7-degree ICCIs. The experimental scan bodies with a vertical stop demonstrated significantly smaller linear displacements in the 11-degree ICCIs.

Extra-cavity modulation of a chirped Gaussian bisoliton

Optical solitons can find important applications in optical fiber communication systems. Here, we simulate extra-cavity modulation of a chirped Gaussian bisoliton in a 1 μm wavelength band. Several different soliton parameters are varied (including the amplitude ratio and time delay of orthogonal components, the projection angle, phase difference, pulse chirps and propagation distances), to effectively change the optical spectra and pulse shapes of the initial input chirped Gaussian bisoliton. For example, when the two branches in the optical fiber modulation system have the same or different fiber lengths, the modulated chirped Gaussian bisoliton will show obviously different properties in the time domain for orthogonally polarized components, while the corresponding optical spectra have no obvious differences. The simulation results reveal the effects of extra-cavity modulation of the chirped Gaussian bisoliton, which further explores the field of soliton shaping out of a fiber laser cavity.

Multi-View Synthesis of Sparse Projection of Absorption Spectra Based on Joint GRU and U-Net

Tunable diode laser absorption spectroscopy (TDLAS) technology, combined with chromatographic imaging algorithms, is commonly used for two-dimensional temperature and concentration measurements in combustion fields. However, obtaining critical temperature information from limited detection data is a challenging task in practical engineering applications due to the difficulty of deploying sufficient detection equipment and the lack of sufficient data to invert temperature and other distributions in the combustion field. Therefore, we propose a sparse projection multi-view synthesis model based on U-Net that incorporates the sequence learning properties of gated recurrent unit (GRU) and the generalization ability of residual networks, called GMResUNet. The datasets used for training all contain projection data with different degrees of sparsity. This study shows that the synthesized full projection data had an average relative error of 0.35%, a PSNR of 40.726, and a SSIM of 0.997 at a projection angle of 4. At projection angles of 2, 8, and 16, the average relative errors of the synthesized full projection data were 0.96%, 0.19%, and 0.18%, respectively. The temperature field reconstruction was performed separately for sparse and synthetic projections, showing that the application of the model can significantly improve the reconstruction accuracy of the temperature field of high-energy combustion.

Unravelling the role of precursors phosphine`s features in governing the reactivity of [MCl2(P-P)] (M = Pd, Pt) towards formation of thiolate complexes via S−S and S−C bond cleavage

Group 10 thiolate complexes have been in the quest zone of research due to pertinent catalytic potential. The present work unravels the role of precursor phosphine`s feature in their reactivity towards 4,6-dimethylpyrimidine-2-thiol and subsequent thiolate complex. Synthesized thiolate complexes were thoroughly characterized using elemental analyses, NMR (1H, 13C{1H}, 31P{1H}), UV–Vis spectroscopy and Single Crystal X-ray diffraction analyses. Treatment of [MCl2(PPh3)2] (M = Pd, Pt) with two equivalents of NaSC4H(4,6-Me)N2 resulted in chelated [Pd{κ-S, κ-N: SC4H(4,6-Me)2N2}{SC4H(4,6-Me)2N2}(PPh3)] (1a) as well as an expected trans compound [Pt{SC4H(4,6-Me)2N2}2(PPh3)2] (1b). A similar reaction with the chelating phosphine ‘dppm’ (dppm = 1,1-bis(diphenylphosphino)methane) as an ancillary ligand resulted in the serendipitous product of composition [Pd2(µ2-S){SC4H(4,6-Me)2N2}2(µ2-dppm)2] (2a) depending upon competitive cleavage of S-S and S-C bond. The reaction of [PdCl2(dppe)] afforded a cis configured compound [Pd{2-SC4H(4,6-Me)2N2}2(dppe)] (2b). Contrary, the similar reaction of [PdCl2(dppp)] results in removal of ‘dppp’ (1,3-bis(diphenylphosphino)propane) yielding the chelated complex [Pd{κ-S, κ-N: SC4H(4,6-Me)2N2}2] (2c). Above all, the reactivity of 4,6-dimethylpyrimidine-2-thiol significantly differs compared to unsubstituted pyrimidyl, pyridyl analogue which has been attributed to the additional richness of electrons/activation in the ring which in turn facilitates competitive reactivity pattern of S-S and S-C bond. The virtue of such activation can easily be understood by the isolation of complex [Pd2(µ2-S){SC4H(4,6-Me)2N2}2(µ2-dppm)2] (2a). Rationalization of results via DFT calculation reveals that projection angle P-M-P (ranging from ∼75 to 92°) driven structural change in the chelating phosphine and associated degree of softness in ligand molecule played a crucial role in governing the resulting product of substitution reaction as dimeric, monomeric and chelated complexes. Thus, projection angle- driven geometrical and electronic structure and variation provide opportunity and direction to efficiently derive biologically as well as academically important complexes.

Visual Field Restriction in the Recognition of Basic Facial Expressions: A Combined Eye Tracking and Gaze Contingency Study.

Uncertainties and discrepant results in identifying crucial areas for emotional facial expression recognition may stem from the eye tracking data analysis methods used. Many studies employ parameters of analysis that predominantly prioritize the examination of the foveal vision angle, ignoring the potential influences of simultaneous parafoveal and peripheral information. To explore the possible underlying causes of these discrepancies, we investigated the role of the visual field aperture in emotional facial expression recognition with 163 volunteers randomly assigned to three groups: no visual restriction (NVR), parafoveal and foveal vision (PFFV), and foveal vision (FV). Employing eye tracking and gaze contingency, we collected visual inspection and judgment data over 30 frontal face images, equally distributed among five emotions. Raw eye tracking data underwent Eye Movements Metrics and Visualizations (EyeMMV) processing. Accordingly, the visual inspection time, number of fixations, and fixation duration increased with the visual field restriction. Nevertheless, the accuracy showed significant differences among the NVR/FV and PFFV/FV groups, despite there being no difference in NVR/PFFV. The findings underscore the impact of specific visual field areas on facial expression recognition, highlighting the importance of parafoveal vision. The results suggest that eye tracking data analysis methods should incorporate projection angles extending to at least the parafoveal level.

4D-Precise: Learning-based 3D motion estimation and high temporal resolution 4DCT reconstruction from treatment 2D+t X-ray projections

Background and ObjectiveIn radiotherapy treatment planning, respiration-induced motion introduces uncertainty that, if not appropriately considered, could result in dose delivery problems. 4D cone-beam computed tomography (4D-CBCT) has been developed to provide imaging guidance by reconstructing a pseudo-motion sequence of CBCT volumes through binning projection data into breathing phases. However, it suffers from artefacts and erroneously characterizes the averaged breathing motion. Furthermore, conventional 4D-CBCT can only be generated post-hoc using the full sequence of kV projections after the treatment is complete, limiting its utility. Hence, our purpose is to develop a deep-learning motion model for estimating 3D+t CT images from treatment kV projection series. MethodsWe propose an end-to-end learning-based 3D motion modelling and 4DCT reconstruction model named 4D-Precise, abbreviated from Probabilistic reconstruction of image sequences from CBCT kV projections. The model estimates voxel-wise motion fields and simultaneously reconstructs a 3DCT volume at any arbitrary time point of the input projections by transforming a reference CT volume. Developing a Torch-DRR module, it enables end-to-end training by computing Digitally Reconstructed Radiographs (DRRs) in PyTorch. During training, DRRs with matching projection angles to the input kVs are automatically extracted from reconstructed volumes and their structural dissimilarity to inputs is penalised. We introduced a novel loss function to regulate spatio-temporal motion field variations across the CT scan, leveraging planning 4DCT for prior motion distribution estimation. ResultsThe model is trained patient-specifically using three kV scan series, each including over 1200 angular/temporal projections, and tested on three other scan series. Imaging data from five patients are analysed here. Also, the model is validated on a simulated paired 4DCT-DRR dataset created using the Surrogate Parametrised Respiratory Motion Modelling (SuPReMo). The results demonstrate that the reconstructed volumes by 4D-Precise closely resemble the ground-truth volumes in terms of Dice, volume similarity, mean contour distance, and Hausdorff distance, whereas 4D-Precise achieves smoother deformations and fewer negative Jacobian determinants compared to SuPReMo. ConclusionsUnlike conventional 4DCT reconstruction techniques that ignore breath inter-cycle motion variations, the proposed model computes both intra-cycle and inter-cycle motions. It represents motion over an extended timeframe, covering several minutes of kV scan series.

Evaluating 3D Simulation Accuracy for Breast Augmentation Outcomes: A Volumetric and Surface Contour Analysis in Chinese Patients.

The use of three-dimensional imaging in breast augmentation with silicone implants has revolutionized the surgery planning process by providing detailed visualizations of expected post-surgical outcomes. This technology enhances the decision-making process, enabling patients to choose their implants with greater confidence and ultimately leading to higher satisfaction with the postoperative outcome. This study aims to assess the accuracy of 3D imaging simulations using the Canfield Vectra XT 3D system in predicting breast augmentation outcomes in Chinese patients, focusing on volume, surface contour, breast anterior-posterior (AP) Projection, and breast internal angle. Our study analyzed female patients who received breast augmentation, documenting their preoperative and three-month postoperative conditions with 3D Vectra XT system images. Exclusions were made for patients undergoing concurrent breast surgeries or those with tuberous or ptotic breasts, due to limitations of the imaging system. Implants used were either round textured or anatomically shaped cohesive silicone gel, inserted subpectorally through trans-axillary or inframammary incisions, based on personalized evaluations. A detailed comparison between preoperative simulations and actual postoperative outcomes was conducted, focusing on volume, surface contour, AP projection, and internal angle variations. Statistical significance was determined through paired T tests, P < 0.05. In the analysis of preoperative simulations for determining postoperative outcomes in breast surgery, our study involving 42 Chinese patients, a total of 84 breasts, was conducted. The results indicated a mean volumetric discrepancy of 21.5 ± 10.3 (SD) cubic centimeters between the simulated and actual postoperative outcomes, achieving an accuracy rate of 91.9%. The root mean square deviation for the breast surface geometry was calculated to be 4.5 ± 1.1 (SD) millimeters (mm), demonstrating a low variance between the predicted and observed outcomes. The investigation found no significant variations across any specific areas of the breast surface, highlighting the uniform accuracy of the simulations across the entire breast. Additionally, the mean differences in Anterior-Posterior (AP) projection and internal angle were determined to be 8.82 ± 5.64 mm and 0.48 ± 1.91 (SD) degrees, respectively. These findings collectively attest to the efficacy of preoperative simulations in accurately predicting the postoperative physical appearance of breasts, thereby providing a valuable tool for surgical planning and improving the consultation process for patients. The Canfield Vectra XT 3D system has proven to be remarkably accurate in predicting the volumetric outcomes of breast augmentation surgery, with an accuracy rate exceeding 91.9%. It stands as a valuable tool for surgeons and patients alike, enhancing the preoperative planning process by offering a realistic preview of surgical results. This advancement not only facilitates a deeper understanding and setting of realistic expectations for patients but also strengthens the communication between patients and surgeons, ultimately leading to higher satisfaction rates with the surgical outcomes. It also emphasizes the significance of detailed documentation and consent processes in protecting against legal repercussions. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Investigation of the functional and biomechanical effect of instrument-assisted soft tissue mobilization technique in individuals with asymptomatic dynamic knee valgus - Randomized controlled trial

Although there are studies showing that myofascial release will increase muscle force production, the contribution of its application alone to muscle force production has not been examined. Aim of the study is to investigate the effect of instrument-assisted soft tissue mobilization (IASTM) on eccentric strength, frontal plane projection angle (FPPA), dynamic (DPS), and static postural stability (SPS), femoral internal rotation (FIR) angle in females with dynamic knee valgus (DKV).A total of 44 recreationally active females with asymptomatic DKV (age: 21,39 ± 1,79, body mass index: 20,09 ± 2,45) participated and were randomly assigned to either control group (CG) or IASTM group (IASTMG).Participants' eccentric contraction strength, FPPA, DPS, SPS, and FIR on the involved leg were measured pre- and post. IASTM application was applied to IASTMG for 6 weeks, twice a week, for 5 min, using Graston Technique® instruments on gluteus medius. CG received no intervention. In comparison of ECS difference values, change in IASTMG was found to be statistically significantly higher than CG (p = .004; p < .01). There was no statistical difference in comparison of FIR and FPPA values (respectively p = .213, p = .360; p < .05). In SPS and DPS evaluation, a statistically significant improvement was observed in favor of IASTMG in comparison of both intergroup and difference values (p < .05 for all). Strength gain without exercise can increase postural stability, but it isn't sufficient to correct faulty movement patterns. We recommend adding IASTM to injury prevention programs, but there is a need to investigate the effect of IASTM with technique correction feedback.

Changes in dynamic quadriceps angle in patients with chronic ankle instability

Background: Changes in dynamic Quadriceps Angle (Q angle) had been studied in healthy subjects and individuals with other musculoskeletal disorders; however, in chronic ankle instability (CAI), it has not yet been determined. The purpose of this study was to investigate the difference in dynamic Q angle of patients with unilateral chronic ankle instability and those without chronic ankle instability. Methods: One-hundred and four participants with and without chronic ankle instability from both genders aged between 18-30 years, with a BMI range of 17.9-27.3, were enrolled into 2 equal groups; a study group and a control group, with mean values of age of the study and control groups (20.8±2.4) and (20.9±3) years respectively and of BMI (24.1±4.3) and (23.8±2.9) kg/m2 respectively. Dynamic Q angle measurement is carried out using dynamic knee valgus (DKV) through the frontal plane projection angle (FPPA) during single limb squat. Results: A statistically significant difference in FPPA angle was observed between the affected limb of the CAI group and controls (P=0.001). Conclusion: The present study suggested that unilateral CAI display an increased knee valgus, suggesting an additional proximal kinematic alteration and chronic maladaptation in the CAI population.

Minimal impact of beam projection angle deviations in skyline (Laurin) view and the efficacy of the anterior border of proximal tibia as a guiding landmark.

Obtaining an optimal knee skyline view is challenging due to inaccuracies in beam projection angles (BPAs) and soft tissue obscuring bony landmarks. This study aimed to assess the impact of BPA deviations on patellofemoral index measurements and assessed the anterior border of the proximal tibia as an anatomic landmark for guiding BPAs. This retrospective study consisted of three parts. The first was a simulation study using 52 CT scans of knees with a 20° flexion contracture to replicate the skyline (Laurin) view. Digitally reconstructed radiographs simulated neutral, 5° downward, and 5° upward tilt BPAs. Five patellofemoral indices (sulcus angle, congruence angle, patellar tilt angle, lateral facet angle, and bisect ratio) were measured and compared. The second part was a proof of concept study on 162 knees to examine patellar indices differences across these BPAs. Lastly, the alignment of the anterior border of the proximal tibia with the BPA tangential to the patellar articular surface was tested from the CT scans. No significant differences in patellofemoral indices were found across various BPAs in both the simulation and proof of concept studies (all p > 0.05). The angle between the anterior border of the proximal tibia and the patellar articular surface was 1.5 ± 5.3°, a statistically significant (p = 0.037) yet clinically acceptable deviation. Patellofemoral indices in skyline view remained consistent regardless of BPA deviations. The anterior border of the proximal tibia proved to be an effective landmark for accurate beam projection.

Projection-Angle-Sensor-Assisted X-ray Computed Tomography for Cylindrical Lithium-Ion Batteries.

X-ray computed tomography (XCT) has become a powerful technique for studying lithium-ion batteries, allowing non-destructive 3D imaging across multiple spatial scales. Image quality is particularly important for observing the internal structure of lithium-ion batteries. During multiple rotations, the existence of cumulative errors and random errors in the rotary table leads to errors in the projection angle, affecting the imaging quality of XCT. The accuracy of the projection angle is an important factor that directly affects imaging. However, the impact of the projection angle on XCT reconstruction imaging is difficult to quantify. Therefore, the required precision of the projection angle sensor cannot be determined explicitly. In this research, we selected a common 18650 cylindrical lithium-ion battery for experiments. By setting up an XCT scanning platform and installing an angle sensor to calibrate the projection angle, we proceeded with image reconstruction after introducing various angle errors. When comparing the results, we found that projection angle errors lead to the appearance of noise and many stripe artifacts in the image. This is particularly noticeable in the form of many irregular artifacts in the image background. The overall variation and residual projection error in detection indicators can effectively reflect the trend in image quality. This research analyzed the impact of projection angle errors on imaging and improved the quality of XCT imaging by installing angle sensors on a rotary table.

Topology observing 3D device reconstruction from continuous-sweep limited angle fluoroscopy.

Minimally invasive procedures usually require navigating a microcatheter and guidewire through endoluminal structures such as blood vessels and airways to sites of the disease. For numerous clinical applications, two-dimensional (2D) fluoroscopy is the primary modality used for real-time image guidance during navigation. However, 2D imaging can pose challenges for navigation in complex structures. Real-time 3D visualization of devices within the anatomic context could provide considerable benefits for these procedures. Continuous-sweep limited angle (CLA) fluoroscopy has recently been proposed to provide a compromise between conventional rotational 3D acquisitions and real-timefluoroscopy. The purpose of this work was to develop and evaluate a noniterative 3D device reconstruction approach for CLA fluoroscopy acquisitions, which takes into account endoluminal topology to avoid impossible paths between disconnectedbranches. The algorithm relies on a static 3D roadmap (RM) of vessels or airways, which may be generated from conventional cone beam CT (CBCT) acquisitions prior to navigation. The RM is converted to a graph representation describing its topology. During catheter navigation, the device is segmented from the live 2D projection images using a deep learning approach from which the centerlines are extracted. Rays from the focal spot to detector pixels representing 2D device points are identified and intersections with the RM are computed. Based on the RM graph, a subset of line segments is selected as candidates to exclude device paths through disconnected branches of the RM. Depth localization for each point along the device is then performed by finding the point closest to the previous 3D reconstruction along the candidate segments. This process is repeated as the projection angle changes for each CLA image frame. The approach was evaluated in a phantom study in which a catheter and guidewire were navigated along five pathways within a complex vessel phantom. The result was compared to static cCBCT acquisitions of the device in the finalposition. The average root mean squared 3D distance between CLA reconstruction and reference centerline was mm. The Euclidean distance at the device tip was mm. The correct pathway was identified during reconstruction in of frames ( ). The percentage of 3D device points reconstructed inside the 3D roadmap was with an average distance of mm between the device points outside the roadmap and the nearest point within theroadmap. This study demonstrates the feasibility of reconstructing curvilinear devices such as catheters and guidewires during endoluminal procedures including intravascular and transbronchial interventions using a noniterative reconstruction approach for CLA fluoroscopy. This approach could improve device navigation in cases where the structure of vessels or airways is complex and includes overlappingbranches.

Propagation of uncertainty for an epipole-dependent model for convergent stereovision structure computation

An analytic model incorporating stereo epipoles is proposed for structure computation using a convergent stereovision setup. The developed model is predicated on the image parameters of both CCD camera sensors, together with two extrinsic parameters, namely the stereo baseline distance and the stereo projection angle of the scene point of interest. In the model, the points on the image planes are measured relative to the principal points, stereo epipoles are featured, and only focal length-normalized camera sensor coordinates are required for structure computation. The reconstruction model could be employed in active vision-based metrology in which the stereo imaging cameras are systematically rotated about their vertical axes relative to each other. The performance of the model is studied, and its accuracy tested by comparing the 3-space coordinates it predicted to the those obtained by a gold standard triangulation and to the ground truth results. In terms of execution speed the proposed reconstruction model exhibited a computation time of 0.6 ms compared to 6.2 ms and 9.9 ms recorded for the direct linear transformation and gold standard triangulation algorithms respectively. The coordinate measurement uncertainties determined by experimental methods are subsequently compared with those obtained by a theoretical approach based on the analytic reconstruction model. Strong correlations were found to exist between the two sets of uncertainty values obtained.

X-ray phase and dark-field computed tomography without optical elements.

X-ray diffusive dark-field imaging, which allows spatially unresolved microstructure to be mapped across a sample, is an increasingly popular tool in an array of settings. Here, we present a new algorithm for phase and dark-field computed tomography based on the x-ray Fokker-Planck equation. Needing only a coherent x-ray source, sample, and detector, our propagation-based algorithm can map the sample density and dark-field/diffusion properties of the sample in 3D. Importantly, incorporating dark-field information in the density reconstruction process enables a higher spatial resolution reconstruction than possible with previous propagation-based approaches. Two sample exposures at each projection angle are sufficient for the successful reconstruction of both the sample density and dark-field Fokker-Planck diffusion coefficients. We anticipate that the proposed algorithm may be of benefit in biomedical imaging and industrial settings.