scholarly journals Handling images of patient postures in arms up and arms down position using a biomechanical skeleton model

2017 ◽  
Vol 3 (2) ◽  
pp. 469-472
Author(s):  
Hendrik Teske ◽  
Kathrin Bartelheimer ◽  
Rolf Bendl ◽  
Eva M. Stoiber ◽  
Kristina Giske
Keyword(s):  
Soft Tissue ◽  
Degrees Of Freedom ◽  
Motion Vector ◽  
Biomechanical Model ◽  
Transformation Model ◽  
Skeleton Model ◽  
Tissue Specific ◽  
Tissue Model ◽  
Anatomical Changes ◽  
Motion Vector Field

AbstractDeformable image registration is gradually becoming the tool of choice for motion extraction during adaptive radiotherapy. Achieving a motion vector field that accurately represents the anatomical changes requires a tissue specific transformation model. Therefore, widely used spline based models most likely fail in appropriately reproducing large anatomical changes such as the arms of the patient being positioned up and down. We present the application of a tissue specific biomechanical model with the goal to mimic patient motion even in presence of large motion. Based on the planning CT, delineated bones are used to represent the rigid anatomy of the patient. We implement ball-and-socket joints between corresponding bones in order to achieve mobility of the skeleton. An inverse kinematics approach enables the propagation of motion between individual bones across their joints, leading to an articulated skeleton that can be controlled by feature points on one or more bones. The transformation of each bone initializes a chainmail based soft tissue model to also propagate the motion into the surrounding heterogeneous soft tissue. Representation of different postures like arms up and down can be achieved within less than 1 s for the skeleton and ∼10 s for the soft tissue. Especially for large anatomical changes, the kinematics approach benefits from the direct articulation at specific joints, considerably lowering the degrees of freedom for motion description. Being the input for the chainmail based soft tissue model, the transformed bones guarantee for its meaningful initialization. The proposed biomechanical skeleton model is promising to facilitate the registration of patients’ anatomy, being positioned with arms up and arms down. The results encourage further refinement of the joints and the soft tissue model.

Motion correction in PET/CT

2005 ◽  
Vol 44 (S 01) ◽  
pp. S46-S50 ◽  
Author(s):  
M. Dawood ◽  
N. Lang ◽  
F. Büther ◽  
M. Schäfers ◽  
O. Schober ◽  
...  
Keyword(s):  
Optical Flow ◽  
Motion Correction ◽  
Motion Vector ◽  
Emission Tomography ◽  
Cardiac Pet ◽  
Novel Approach ◽  
Positron Emission ◽  
Pet Ct ◽  
Flow Algorithm ◽  
Motion Vector Field

Summary:Motion in PET/CT leads to artifacts in the reconstructed PET images due to the different acquisition times of positron emission tomography and computed tomography. The effect of motion on cardiac PET/CT images is evaluated in this study and a novel approach for motion correction based on optical flow methods is outlined. The Lukas-Kanade optical flow algorithm is used to calculate the motion vector field on both simulated phantom data as well as measured human PET data. The motion of the myocardium is corrected by non-linear registration techniques and results are compared to uncorrected images.

Application of combined three-dimensional bone and soft tissue model

1998 ◽  
Vol 27 (6) ◽  
pp. 482-484 ◽  
Author(s):  
Gert Santler ◽  
Hans Kaercher ◽  
Alexander Gaggl ◽  
Guenter Schultes
Keyword(s):  
Soft Tissue ◽  
Three Dimensional ◽  
Tissue Model

scholarly journals An anisotropic viscoelastic soft tissue model at large strains

PAMM ◽  
2006 ◽  
Vol 6 (1) ◽  
pp. 129-130
Author(s):  
Uwe-Jens Görke ◽  
Hubert Günther ◽  
Anke Bucher ◽  
Reiner Kreißig
Keyword(s):  
Soft Tissue ◽  
Large Strains ◽  
Tissue Model

Stabilizing 3D in vivo intravital microscopy images with an iteratively refined soft-tissue model for immunology experiments

2015 ◽  
Vol 64 ◽  
pp. 246-260 ◽  
Author(s):  
Iván Gómez-Conde ◽  
Susana S. Caetano ◽  
Carlos E. Tadokoro ◽  
David N. Olivieri
Keyword(s):  
Soft Tissue ◽  
Intravital Microscopy ◽  
Tissue Model ◽  
Microscopy Images

Simulated Compensatory Motion of Transradial Prostheses

2008 ◽  
Author(s):  
Derek Lura ◽  
Rajiv Dubey ◽  
Stephanie L. Carey ◽  
M. Jason Highsmith
Keyword(s):  
Range Of Motion ◽  
Shoulder Joint ◽  
Degrees Of Freedom ◽  
Biomechanical Model ◽  
Elbow Flexion ◽  
Limited Range ◽  
Joint Movement ◽  
Range Of Movement ◽  
Limited Range Of Motion ◽  
Compensatory Motion

The prostheses used by the majority of persons with hand/arm amputations today have a very limited range of motion. Transradial (below the elbow) amputees lose the three degrees of freedom provided by the wrist and forearm. Some myoeletric prostheses currently allow for forearm pronation and supination (rotation about an axis parallel to the forearm) and the operation of a powered prosthetic hand. Older body-powered prostheses, incorporating hooks and other cable driven terminal devices, have even fewer degrees of freedom. In order to perform activities of daily living (ADL), a person with amputation(s) must use a greater than normal range of movement from other body joints to compensate for the loss of movement caused by the amputation. By studying the compensatory motion of prosthetic users we can understand the mechanics of how they adapt to the loss of range of motion in a given limb for select tasks. The purpose of this study is to create a biomechanical model that can predict the compensatory motion using given subject data. The simulation can then be used to select the best prosthesis for a given user, or to design prostheses that are more effective at selected tasks, once enough data has been analyzed. Joint locations necessary to accomplish the task with a given configuration are calculated by the simulation for a set of prostheses and tasks. The simulation contains a set of prosthetic configurations that are represented by parameters that consist of the degrees of freedom provided by the selected prosthesis. The simulation also contains a set of task information that includes joint constraints, and trajectories which the hand or prosthesis follows to perform the task. The simulation allows for movement in the wrist and forearm, which is dependent on the prosthetic configuration, elbow flexion, three degrees of rotation at the shoulder joint, movement of the shoulder joint about the sternoclavicular joint, and translation and rotation of the torso. All joints have definable restrictions determined by the prosthesis, and task.

scholarly journals Effect of time complexities and variation of mass spring model parameters on surgical simulation

2014 ◽  
Vol 9 (4) ◽  
Author(s):  
Salina Sulaiman ◽  
Tan Sing Yee ◽  
Abdullah Bade
Keyword(s):  
Soft Tissue ◽  
Human Liver ◽  
Soft Tissues ◽  
Surgical Simulation ◽  
Model Parameters ◽  
Spring Model ◽  
Surgical Simulator ◽  
Tissue Model ◽  
Mass Spring Model ◽  
Mass Spring

Physically based models assimilate organ-specific material properties, thus they are suitable in developing a surgical simulation. This study uses mass spring model (MSM) to represent the human liver because MSM is a discrete model that is potentially more realistic than the finite element model (FEM). For a high-end computer aided medical technology such as the surgical simulator, the most important issues are to fulfil the basic requirement of a surgical simulator. Novice and experienced surgeons use surgical simulator for surgery training and planning. Therefore, surgical simulation must provide a realistic and fast responding virtual environment. This study focuses on fulfilling the time complexity and realistic of the surgical simulator. In order to have a fast responding simulation, the choice of numerical integration method is crucial. This study shows that MATLAB ode45 is the fastest method compared to 2nd ordered Euler, MATLAB ode113, MATLAB ode23s and MATLAB ode23t. However, the major issue is human liver consists of soft tissues. In modelling a soft tissue model, we need to understand the mechanical response of soft tissues to surgical manipulation. Any interaction between haptic device and the liver model may causes large deformation and topology change in the soft tissue model. Thus, this study investigates and presents the effect of varying mass, damping, stiffness coefficient on the nonlinear liver mass spring model. MATLAB performs and shows simulation results for each of the experiment. Additionally, the observed optimal dataset of liver behaviour is applied in SOFA (Simulation Open Framework Architecture) to visualize the major effect.

scholarly journals Motion-Compensated Frame Interpolation Using Cellular Automata-Based Motion Vector Smoothing

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Ran Li ◽  
Ying Yin ◽  
Fengyuan Sun ◽  
Yanling Li ◽  
Lei You
Keyword(s):  
Cellular Automata ◽  
Motion Vector ◽  
Video Sequences ◽  
Frame Interpolation ◽  
Temporal Domain ◽  
Video Frames ◽  
Motion Compensated Frame Interpolation ◽  
Motion Vector Field ◽  
The Common ◽  
Temporal Symmetry

Motion-Compensated Frame Interpolation (MCFI) is one of the common temporal-domain tamper operations, and it is used to produce faked video frames for improving the visual qualities of video sequences. The instability of temporal symmetry results in many incorrect Motion Vectors (MVs) for Bidirectional Motion Estimation (BME) in MCFI. The existing Motion Vector Smoothing (MVS) works often oversmooth or revise correct MVs as wrong ones. To overcome this problem, we propose a Cellular Automata-based MVS (CA-MVS) algorithm to smooth the Motion Vector Field (MVF) output by BME. In our work, a cellular automaton is constructed to deduce MV outliers according to a defined local evolution rule. By performing CA-based evolution in a loop iteration, we gradually expose MV outliers and reduce incorrect MVs resulting from oversmoothing as many as possible. Experimental results show the proposed algorithm can improve the accuracy of BME and provide better objective and subjective interpolation qualities when compared with the traditional MVS algorithms.

An appropriate biomechanical model of seated human subjects exposed to whole-body vibration

2021 ◽  
pp. 146441932110394
Author(s):  
Raj Desai ◽  
Anirban Guha ◽  
Pasumarthy Seshu
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Computational Cost ◽  
Biomechanical Model ◽  
Whole Body ◽  
Body Parts ◽  
Lumped Parameter ◽  
Long Duration ◽  
The One ◽  
The Right

Long duration automobile-induced vibration is the cause of many ailments to humans. Predicting and mitigating these vibrations through seat requires a good model of seated human body. A good model is the one that strikes the right balance between modelling difficulty and simulation results accuracy. Increasing the number of body parts which have been separately modelled and increasing the number of ways these parts are connected to each other increase the number of degrees of freedom of the entire model. A number of such models have been reported in the literature. These range from simple lumped parameter models with limited accuracy to advanced models with high computational cost. However, a systematic comparison of these models has not been reported till date. This work creates eight such models ranging from 8 to 26 degrees of freedom and tries to identify the model which strikes the right balance between modelling complexity and results accuracy. A comparison of the models’ prediction with experimental data published in the literature allows the identification of a 12 degree of freedom backrest supported model as optimum for modelling complexity and prediction accuracy.

scholarly journals Tissue-specific transformation model for CT-images

2017 ◽  
Vol 3 (2) ◽  
pp. 525-528
Author(s):  
Kathrin Bartelheimer ◽  
Hendrik Teske ◽  
Rolf Bendl ◽  
Kristina Giske
Keyword(s):  
Ct Images ◽  
Tissue Growth ◽  
Transformation Model ◽  
Deformation Analysis ◽  
Skeleton Model ◽  
Volume Calculation ◽  
Model Based ◽  
The Impact ◽  
Model Characteristic ◽  
Insight Into

AbstractDuring radiotherapy, posture changes and volume changing deformations like growing or shrinking tissue result in anatomical deformations. The basis for investigating the impact of such deformations on dose uncertainties, are model-based tools for deformation analysis. In this context, we propose a transformation model based on the information of CT-images, which allows an on-the-fly calculation of voxel volumes. Our model is based on the concept of the chainmail algorithm and describes deformation on voxel-level. With an exemplary input of a set of landmark pairs, generated by a kinematic head-and-neck skeleton model, CT-images (512x512x126 voxel) can be deformed with an on-the-fly volume calculation in less than 70s. The volume calculation delivers insight into model-characteristic volume changes and is a prerequisite for implementing tissue growth and shrinkage.

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