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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/28223012/3d-measurements-in-conventional-x-ray-imaging-with-rgb-d-sensors
#1
Francisco Albiol, Alberto Corbi, Alberto Albiol
A method for deriving 3D internal information in conventional X-ray settings is presented. It is based on the combination of a pair of radiographs from a patient and it avoids the use of X-ray-opaque fiducials and external reference structures. To achieve this goal, we augment an ordinary X-ray device with a consumer RGB-D camera. The patient' s rotation around the craniocaudal axis is tracked relative to this camera thanks to the depth information provided and the application of a modern surface-mapping algorithm...
February 17, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28215399/restoring-standing-capabilities-with-feedback-control-of-functional-neuromuscular-stimulation-following-spinal-cord-injury
#2
REVIEW
Raviraj Nataraj, Musa L Audu, Ronald J Triolo
This paper reviews the field of feedback control for neuroprosthesis systems that restore advanced standing function to individuals with spinal cord injury. Investigations into closed-loop control of standing by functional neuromuscular stimulation (FNS) have spanned three decades. The ultimate goal for FNS standing control systems is to facilitate hands free standing and enabling the user to perform manual functions at self-selected leaning positions. However, most clinical systems for home usage currently only provide basic upright standing using preprogrammed stimulation patterns...
February 15, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28209345/multiobjective-optimization-of-cartilage-stress-for-non-invasive-patient-specific-recommendations-of-high-tibial-osteotomy-correction-angle-a-novel-method-to-investigate-alignment-correction
#3
Keke Zheng, Corey J Scholes, Junning Chen, David Parker, Qing Li
Medial opening wedge high tibial osteotomy (MOWHTO) is a surgical procedure to treat knee osteoarthritis associated with varus deformity. However, the ideal final alignment of the Hip-Knee-Ankle (HKA) angle in the frontal plane, that maximizes procedural success and post-operative knee function, remains controversial. Therefore, the purpose of this study was to introduce a subject-specific modeling procedure in determining the biomechanical effects of MOWHTO alignment on tibiofemoral cartilage stress distribution...
February 13, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28196652/simulation-of-fetal-heart-rate-variability-with-a-mathematical-model
#4
Germaine J L M Jongen, M Beatrijs van der Hout-van der Jagt, S Guid Oei, Frans N van de Vosse, Peter H M Bovendeerd
In the clinic, the cardiotocogram (CTG), the combined registration of fetal heart rate (FHR) and uterine contractions, is used to predict fetal well-being. Amongst others, fetal heart rate variability (FHRV) is an important indicator of fetal distress. In this study we add FHRV to our previously developed CTG simulation model, in order to improve its use as a research and educational tool. We implemented three sources of variability by applying either 1/f or white noise to the peripheral vascular resistance, baroreceptor output, or efferent vagal signal...
February 11, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28190610/optimised-analytical-models-of-the-dielectric-properties-of-biological-tissue
#5
Saqib Salahuddin, Emily Porter, Finn Krewer, Martin O' Halloran
The interaction of electromagnetic fields with the human body is quantified by the dielectric properties of biological tissues. These properties are incorporated into complex numerical simulations using parametric models such as Debye and Cole-Cole, for the computational investigation of electromagnetic wave propagation within the body. These parameters can be acquired through a variety of optimisation algorithms to achieve an accurate fit to measured data sets. A number of different optimisation techniques have been proposed, but these are often limited by the requirement for initial value estimations or by the large overall error (often up to several percentage points)...
February 9, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28173978/the-effects-of-tibia-profile-distraction-angle-and-knee-load-on-wedge-instability-and-hinge-fracture-a-finite-element-study
#6
Pei-Wei Weng, Chia-Hsien Chen, Chu-An Luo, Jui-Sheng Sun, Yang-Hwei Tsuang, Cheng-Kung Cheng, Shang-Chih Lin
Several plate systems for high tibial osteotomy (HTO) have been developed to stabilize the opening wedge of an osteotomized tibia. Among them, the TomoFix system, having a quasi-straight and T-shaped design, has been widely adopted in the literature. However, this system is implemented by inserting a lag (i.e., cortical) screw through the proximal combi-hole, to deform the plate and pull the distal tibia toward the plate. This process potentially induces plate springback and creates an elastic preload on the osteotomized tibia, especially at the lateral hinge of the distracted wedge...
February 4, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28169197/assessing-the-immediate-impact-of-botulinum-toxin-injection-on-impedance-of-spastic-muscle
#7
Xiaoyan Li, Henry Shin, Le Li, Elaine Magat, Sheng Li, Ping Zhou
This study aimed to investigate the immediate impacts of Botulinum Toxin A (BoNT-A) injections on the inherent electrical properties of spastic muscles using a newly developed electrical impedance myography (EIM) technique. Impedance measures were performed before and after a BoNT-A injection in biceps brachii muscles of 14 subjects with spasticity. Three major impedance variables, resistance (R), reactance (X) and phase angle (θ) were obtained from three different configurations, and were evaluated using the conventional EIM frequency at 50kHz as well as multiple frequency analysis...
February 3, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28161107/exploration-of-force-myography-and-surface-electromyography-in-hand-gesture-classification
#8
Xianta Jiang, Lukas-Karim Merhi, Zhen Gang Xiao, Carlo Menon
Whereas pressure sensors increasingly have received attention as a non-invasive interface for hand gesture recognition, their performance has not been comprehensively evaluated. This work examined the performance of hand gesture classification using Force Myography (FMG) and surface Electromyography (sEMG) technologies by performing 3 sets of 48 hand gestures using a prototyped FMG band and an array of commercial sEMG sensors worn both on the wrist and forearm simultaneously. The results show that the FMG band achieved classification accuracies as good as the high quality, commercially available, sEMG system on both wrist and forearm positions; specifically, by only using 8 Force Sensitive Resisters (FSRs), the FMG band achieved accuracies of 91...
February 1, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28161106/dynamic-assessment-of-center-of-pressure-measurements-from-an-instrumented-amti-treadmill-with-controlled-precision
#9
Emma Fortune, Jeremy Crenshaw, Vipul Lugade, Kenton R Kaufman
With the increasing use of instrumented force treadmills in biomechanical research, it is imperative that the validity of center of pressure (COP) measurements is established. The study aims were to compare an instrumented treadmill's static-belt COP accuracy to that of a floor-embedded platform, develop a novel method to quantify dynamic-belt COP accuracy with controlled precision and perform an initial investigation of how dynamic COP accuracy changes with weight and velocity. Static COP accuracy was assessed by applying a force while moving a rigid rod in a circular clockwise motion at nine positions of interest on the two treadmill and two ground-embedded force plates...
February 1, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28159451/interfragmentary-compression-and-pull-out-properties-of-6-5-mm-ao-cancellous-lag-screws-in-a-uniform-synthetic-material-during-tightening-procedures
#10
Peidong Sun, Daqiang Xu, Weidong Zhao, Peifeng Jiao, Zeyu Li, Chang Liu, Jun Ouyang
AO lag screws are widely used in surgical intra-articular fracture treatment for anatomical reduction and rigid fixation. Interfragmentary compressive force (IFCF) and pull-out strength (POS) are two critical parameters generated by AO lag screws during tightening, and both of these parameters could be used to estimate screw insert conditions to prevent screw stripping. The aim of this study is to evaluate the IFCF and POS of AO cancellous screws inserted into uniform synthetic cancellous bone during tightening procedures...
January 31, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28159450/laser-fabrication-of-electrical-feedthroughs-in-polymer-encapsulations-for-active-implantable-medical-devices
#11
Zara Gough, Cedric Chaminade, Philip Barclay-Monteith, Annukka Kallinen, Wenwen Lei, Rajesh Ganesan, John Grace, David R McKenzie
Hermetic electrical feedthroughs are essential for safe and functional active implantable biomedical devices and for a wide range of other applications such as batteries, supercapacitors, OLEDs and solar cells. Ceramics and metals have previously been the materials of choice for encapsulations, while polymers have advantages of ease of mass production and end user compatibility. We demonstrate a laser sealing technology that gives hermetic, mechanically strong feedthroughs with low electrical resistance in a polyetheretherketone (PEEK) encapsulation...
January 31, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28159449/a-surface-wave-elastography-technique-for-measuring-tissue-viscoelastic-properties
#12
Xiaoming Zhang
A surface wave elastography method is proposed to study the viscoelastic properties of skin by measuring the surface wave speed and attenuation on the skin. Experiments were carried out on porcine skin tissues. The surface wave speed is measured by the change of phase with distance. The wave attenuation is measured by the decay of wave amplitude with distance. The change of viscoelastic properties with temperature was studied at room and body temperatures. The wave speed was 1.83m/s at 22°C but reduced to 1...
January 31, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28159448/characterization-of-micro-resonator-based-on-enhanced-metal-insulator-semiconductor-capacitor-for-glucose-recognition
#13
Rajendra Dhakal, E S Kim, Yong-Hwa Jo, Sung-Soo Kim, Nam-Young Kim
We present a concept for the characterization of micro-fabricated based resonator incorporating air-bridge metal-insulator-semiconductor (MIS) capacitor to continuously monitor an individual's state of glucose levels based on frequency variation. The investigation revealed that, the micro-resonator based on MIS capacitor holds considerable promise for implementation and recognition as a glucose sensor for human serum. The discrepancy in complex permittivity as a result of enhanced capacitor was achieved for the detection and determination of random glucose concentration levels using a unique variation of capacitor that indeed results in an adequate variation of the resonance frequency...
January 31, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28159447/medical-device-guidebook-a-browser-information-resource-for-medical-device-users
#14
Douglas M Clarkson
A web based information resource - the 'Medical Device Guidebook' - for the enabling of safe use of medical devices is described. Medical devices are described within a 'catalogue' of specific models and information on a specific model is provided within a consistent set of information 'keys'. These include 'user manuals', 'points of caution', 'clinical use framework', 'training/assessment material', 'frequently asked questions', 'authorised user comments' and 'consumables'. The system allows identification of known risk/hazards associated with specific devices, triggered, for example, by national alerts or locally raised safety observations...
January 31, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28126422/three-dimensional-intervertebral-range-of-motion-in-the-cervical-spine-does-the-method-of-calculation-matter
#15
William J Anderst, Yashar Aucie
Intervertebral range of motion (ROM) is commonly calculated using ordered rotations or projection angles. Ordered rotations are sequence-dependent, and projection angles are dependent upon on which orientation vectors are projected. This study assessed the effect of calculation method on intervertebral ROM in the subaxial cervical spine (C3-C7) during in vivo dynamic, three-dimensional, functional movement. Biplane radiographs were collected at 30 images per second while 29 participants performed full ROM flexion/extension, axial rotation and lateral bending movements of their cervical spine...
January 23, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28126421/a-novel-fully-automatic-measurement-of-apparent-breast-volume-from-trunk-surface-mesh
#16
Lama Seoud, Joyce Ramsay, Stefan Parent, Farida Cheriet
This paper presents a novel method for assessing apparent breast volume from trunk surface mesh without any manual intervention. The proposed method requires a closed and smooth triangular mesh of the trunk. It comprises four main steps: automatic nipple localization, automatic breasts delineation, chest-wall interpolation and volume computation. The mean curvature is computed for each vertex using a quadratic fitting approach and used as an indicator to determine the convex fold of the breasts. The delineation is modeled as an ellipse in the frontal plane and all the vertices inside it are removed...
January 23, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28126420/respiratory-effort-from-the-photoplethysmogram
#17
Paul S Addison
The potential for a simple, non-invasive measure of respiratory effort based on the pulse oximeter signal - the photoplethysmogram or 'pleth' - was investigated in a pilot study. Several parameters were developed based on a variety of manifestations of respiratory effort in the signal, including modulation changes in amplitude, baseline, frequency and pulse transit times, as well as distinct baseline signal shifts. Thirteen candidate parameters were investigated using data from healthy volunteers. Each volunteer underwent a series of controlled respiratory effort maneuvers at various set flow resistances and respiratory rates...
January 23, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28126419/determining-3d-scapular-orientation-with-scapula-models-and-biplane-2d-images
#18
Kristen F Nicholson, R Tyler Richardson, Freeman Miller, James G Richards
This study evaluated a strategy for identifying 3D scapulothoracic orientation using bilateral X-ray scans and 3D scapula models. Both subject-specific scapula models and a scaled general model were utilized. 3D scapulothoracic orientations obtained from X-rays were compared to motion capture data. "Subjects" consisted of a skeletal model of a human torso and ten real bone scapulae. Retroreflective markers were placed on the scapulae and a three-marker triad was placed on the trunk. Marker positions were recorded using an eight camera motion capture system...
January 23, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28111069/mechanical-characterization-and-comparison-of-energy-storage-and-return-prostheses
#19
Stacey M Rigney, Anne Simmons, Lauren Kark
The suitability of finite element analysis (FEA) for standardizing the mechanical characterization of energy storage and return (ESAR) prostheses was investigated. A methodology consisting of both experimental and numerical analysis was proposed and trialed for the Vari-flex(®) Modular(TM), Flex-foot Cheetah and Cheetah Xtreme by Össur(®) and a 1E90 Sprinter by Ottobock(®). Gait analysis was conducted to determine suitable orientation angles for non-destructive testing (NDT) of the ESAR prostheses followed by a quasi-static inverse FEA procedure within COMSOL Multiphysics(®), where the NDT conditions were replicated to determine the homogenized material properties of the prostheses...
January 20, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28109564/development-of-a-surgical-navigation-system-based-on-3d-slicer-for-intraoperative-implant-placement-surgery
#20
Xiaojun Chen, Lu Xu, Huixiang Wang, Fang Wang, Qiugen Wang, Ron Kikinis
Implant placement has been widely used in various kinds of surgery. However, accurate intraoperative drilling performance is essential to avoid injury to adjacent structures. Although some commercially-available surgical navigation systems have been approved for clinical applications, these systems are expensive and the source code is not available to researchers. 3D Slicer is a free, open source software platform for the research community of computer-aided surgery. In this study, a loadable module based on Slicer has been developed and validated to support surgical navigation...
January 18, 2017: Medical Engineering & Physics
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