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13 pages, 2079 KiB

Open AccessArticle

A Genetic Algorithm for Three-Dimensional Discrete Tomography

by Elena Toscano and Cesare Valenti

Symmetry 2024, 16(7), 923; https://doi.org/10.3390/sym16070923 - 19 Jul 2024

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Discrete tomography is a specific case of computerized tomography that deals with the reconstruction of objects made of a few density values on a discrete lattice of points (integer valued coordinates). In the general case of computerized tomography, several hundreds of projections are required to obtain a single high-resolution slice of the object; in the case of discrete tomography, projections of an object made by just one homogeneous material are sums along very few angles of the pixel values, which can be thought to be 0’s or 1’s without loss of generality. Genetic algorithms are global optimization techniques with an underlying random approach and, therefore, their convergence to a solution is provided in a probabilistic sense. We present here a genetic algorithm able to straightforwardly reconstruct binary objects in the three-dimensional space. To the best of our knowledge, our methodology is the first to require no model of the shape (e.g., periodicity, convexity or symmetry) to reconstruct. Experiments were carried out to test our new approach in terms of computational time and correctness of the solutions. Over the years, discrete tomography has been studied for many interesting applications to computer vision, non-destructive reverse engineering and industrial quality control, electron microscopy, X-rays crystallography, biplane angiography, data coding and compression. Full article

(This article belongs to the Special Issue Feature Papers in Mathematics Section)

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11 pages, 3124 KiB

Open AccessArticle

Digital Subtraction Angiography of Cerebral Arteries: Influence of Cranial Dimensions on X-ray Tube Performance

by Sandra Modlińska, Łukasz Czogalik, Marcin Rojek, Piotr Dudek, Michał Janik, Sylwia Mielcarska and Jakub Kufel

J. Clin. Med. 2024, 13(10), 3002; https://doi.org/10.3390/jcm13103002 - 20 May 2024

Cited by 1 | Viewed by 1721

Abstract

(1) Background. Digital subtraction angiography (DSA) is indispensable for diagnosing cerebral aneurysms due to its superior imaging precision. However, optimizing X-ray parameters is crucial for accurate diagnosis, with X-ray tube settings significantly influencing image quality. Understanding the relationship between skull dimensions and X-ray parameters is pivotal for tailoring imaging protocols to individual patients. (2) Methods. A retrospective analysis of DSA data from a single center was conducted, involving 251 patients. Cephalometric measurements and statistical analyses were performed to assess correlations between skull dimensions and X-ray tube parameters (voltage and current). (3) Results. The study revealed significant correlations between skull dimensions and X-ray tube parameters, highlighting the importance of considering individual anatomical variations. Gender-based differences in X-ray parameters were observed, emphasizing the need for personalized imaging protocols. (4) Conclusions. Personalized approaches to DSA imaging, integrating individual anatomical variations and gender-specific differences, are essential for optimizing diagnostic outcomes. While this study provides valuable insights, further research across multiple centers and diverse imaging equipment is warranted to validate these findings. Full article

(This article belongs to the Special Issue Technological Advancements and Clinical Innovations in Diagnostic and Interventional Radiology)

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12 pages, 4910 KiB

Open AccessArticle

Sensor-to-Bone Calibration with the Fusion of IMU and Bi-Plane X-rays

by Xavier Gasparutto, Kevin Rose-Dulcina, Gautier Grouvel, Peter DiGiovanni, Lena Carcreff, Didier Hannouche and Stéphane Armand

Sensors 2024, 24(2), 419; https://doi.org/10.3390/s24020419 - 10 Jan 2024

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Abstract

Inertial measurement units (IMUs) need sensor-to-segment calibration to measure human kinematics. Multiple methods exist, but, when assessing populations with locomotor function pathologies, multiple limitations arise, including holding postures (limited by joint pain and stiffness), performing specific tasks (limited by lack of selectivity) or hypothesis on limb alignment (limited by bone deformity and joint stiffness). We propose a sensor-to-bone calibration based on bi-plane X-rays and a specifically designed fusion box to measure IMU orientation with respect to underlying bones. Eight patients undergoing total hip arthroplasty with bi-plane X-rays in their clinical pathway participated in the study. Patients underwent bi-plane X-rays with fusion box and skin markers followed by a gait analysis with IMUs and a marker-based method. The validity of the pelvis, thigh and hip kinematics measured with a conventional sensor-to-segment calibration and with the sensor-to-bone calibration were compared. Results showed (1) the feasibility of the fusion of bi-plane X-rays and IMUs in measuring the orientation of anatomical axes, and (2) higher validity of the sensor-to-bone calibration for the pelvic tilt and similar validity for other degrees of freedom. The main strength of this novel calibration is to remove conventional hypotheses on joint and segment orientations that are frequently violated in pathological populations. Full article

(This article belongs to the Section Wearables)

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11 pages, 4712 KiB

Open AccessArticle

In Vivo Analysis of the Dynamic Motion Stability Characteristics of Geese’s Neck

by Jiajia Wang, Haoxuan Sun, Wenfeng Jia, Fu Zhang, Zhihui Qian, Xiahua Cui, Lei Ren and Luquan Ren

Biomimetics 2022, 7(4), 160; https://doi.org/10.3390/biomimetics7040160 - 12 Oct 2022

Cited by 3 | Viewed by 2372

Abstract

The goose’s neck is an excellent stabilizing organ with its graceful neck curves and flexible movements. However, the stabilizing mechanism of the goose’s neck remains unclear. This study adopts a dynamic in vivo experimental method to obtain continuous and accurate stable motion characteristics of the goose’s cervical vertebra. Firstly, the results showed that when the body of a goose was separately moved back and forth along the Y direction (front and back) and Z direction (up and down), the goose’s neck can significantly stabilize the head. Then, because of the limitation of the X-ray imaging area, the three-dimensional intervertebral rotational displacements for vertebrae C4–C8 were obtained, and the role that these five segments play in the stabilization of the bird’s neck was analyzed. This study reveals that the largest range of the adjacent vertebral rotational movement is around the X-axis, the second is around the Y-axis, and the smallest is around the Z-axis. This kinematic feature is accord with the kinematic feature of the saddle joint, which allows the flexion/around X-axis and lateral bending/around Y-axis, and prevents axial rotation/around Z-axis. Full article

(This article belongs to the Special Issue Dynamical Response of Biological System and Biomaterial)

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16 pages, 3226 KiB

Open AccessArticle

Reconstruction of Three-Dimensional Tibiofemoral Kinematics Using Single-Plane Fluoroscopy and a Personalized Kinematic Model

by Cheng-Chung Lin, Hsuan-Lun Lu, Tung-Wu Lu, Chia-Yang Wang, Jia-Da Li, Mei-Ying Kuo and Horng-Chuang Hsu

Appl. Sci. 2021, 11(20), 9415; https://doi.org/10.3390/app11209415 - 11 Oct 2021

Cited by 1 | Viewed by 2577

Abstract

Model-based 3D/2D image registration using single-plane fluoroscopy is a common setup to determine knee joint kinematics, owing to its markerless aspect. However, the approach was subjected to lower accuracies in the determination of out-of-plane motion components. Introducing additional kinematic constraints with an appropriate anatomical representation may help ameliorate the reduced accuracy of single-plane image registration. Therefore, this study aimed to develop and evaluate a multibody model-based tracking (MbMBT) scheme, embedding a personalized kinematic model of the tibiofemoral joint for the measurement of tibiofemoral kinematics. The kinematic model was consisted of three ligaments and an articular contact mechanism. The knee joint activities in six volunteers during isolated knee flexion, lunging, and sit-to-stand motions were recorded with a biplane X-ray imaging system. The tibiofemoral kinematics determined with the MbMBT and mediolateral view fluoroscopic images were compared against those determined using biplane fluoroscopic images. The MbMBT was demonstrated to yield tibiofemoral kinematics with precision values in the range from 0.1 mm to 1.1 mm for translations and from 0.2° to 1.3° for rotations. The constraints provided by the kinematic model were shown to effectively amend the nonphysiological tibiofemoral motion and not compromise the image registration accuracy with the proposed MbMBT scheme. Full article

(This article belongs to the Special Issue Biomechanics and Human Motion Analysis)

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21 pages, 5087 KiB

Open AccessArticle

An Automated Three-Dimensional Bone Pose Tracking Method Using Clinical Interleaved Biplane Fluoroscopy Systems: Application to the Knee

by Cheng-Chung Lin, Tung-Wu Lu, Jia-Da Li, Mei-Ying Kuo, Chien-Chun Kuo and Horng-Chuang Hsu

Appl. Sci. 2020, 10(23), 8426; https://doi.org/10.3390/app10238426 - 26 Nov 2020

Cited by 10 | Viewed by 3555

Abstract

Model-based tracking of the movement of the tibiofemoral joint via a biplane X-ray imaging system has been commonly used to reproduce its accurate, three-dimensional kinematics. To accommodate the approaches to existing clinical asynchronous biplane fluoroscopy systems and achieve comparable accuracy, this study proposed an automated model-based interleaved biplane fluoroscopy image tracking scheme (MIBFT) by incorporating information of adjacent image frames. The MIBFT was evaluated with a cadaveric study conducted on a knee specimen. The MIBFT reproduced skeletal poses and tibiofemoral kinematics that were in good agreement with the standard reference kinematics provided by an optical motion capture system, in which the root-mean-squared (Rms) errors of the skeletal pose parameters ranged from 0.11 to 0.35 mm in translation and 0.18 to 0.49° in rotation. The influences of rotation speed on the pose errors were below 0.23 mm and 0.26°. The MIBFT-determined bias, precision, and Rms error were comparable to those of the reported model-based tracking techniques using custom-made synchronous biplane fluoroscopy. The results suggested that the further use of the clinical imaging system is feasible for the noninvasive and precise examination of dynamic joint functions and kinematics in clinical practice and biomechanical research. Full article

(This article belongs to the Special Issue Skeletal Biomechanics)

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