3D Motion Tracking Research Articles

Posttraumatic midshaft clavicular shortening does not result in relevant functional outcome changes

Background and purpose — Shoulder function may be changed after healing of a nonoperatively treated clavicular fracture, especially in cases of clavicular shortening or mal-union. We investigated scapular orientations and functional outcome in healed clavicular fractures with and without clavicular shortening.Patients and methods — 32 participants with a healed nonoperatively treated midshaft clavicular fracture were investigated. Motions of the thorax, arm, and shoulder were recorded by standardized electromagnetic 3D motion tracking. The DASH score and Constant-Murley score were used to evaluate functional outcome. Orientation of the scapula and humerus at rest and during standardized tasks, and strength and function of the affected shoulders were compared with corresponding values for the uninjured contralateral shoulders.Results — Mean clavicular shortening was 25 mm (SD 16). Scapula protraction had increased by mean 4.4° in rest position in the affected shoulders. During abduction, slightly more protraction, slightly more lateral rotation, and slightly less backward tilt was found for the affected shoulders. For anteflexion, the scapular orientations of the affected shoulders also showed slightly increased protraction, slightly increased lateral rotation, and slightly reduced backward tilt. Scapulohumeral kinematics, maximum humerus angles, and strength were not associated with the degree of clavicular shortening. All participants had excellent performance on the Constant-Murley score and DASH score.Interpretation — Scapulohumeral kinematics in shoulders with a healed clavicular fracture differ from those in uninjured shoulders, but these changes are small, do not result in clinically relevant changes in outcome, and do not relate to the amount of clavicular shortening. These findings do not support routine operative reduction and fixation of shortened midshaft clavicular fractures based on the argument of functional outcome.

Preliminary testing of a novel bilateral plating technique for treating periprosthetic fractures of the distal femur

BackgroundCurrent stabilization methods for periprosthetic fractures of the distal femur are inadequate in achieving fracture fixation, with complication rates as high as 29%. A major contributor to poor outcomes is that these methods rely only on screw purchase in the bone to maintain fracture reduction. We designed, manufactured and evaluated a novel plating method that utilizes the femoral prosthesis to enhance stability for treatment of distal femoral periprosthetic fractures. MethodsMedial and lateral plates were designed and manufactured based on geometry of a synthetic femur and femoral prosthesis. The two plates were linked via a compression screw and a small tab on each plate that inserted into pre-existing slots on the prosthesis. Mechanical tests (500N compression or 250N anterior directed cantilever bending), were performed on synthetic femurs with simple transverse fractures (3mm gap) just superior to the distal femoral prosthesis that were stabilized using either the prototype plates or a single lateral plate. Translational movements of the fracture site during loading were measured using 3D motion tracking. FindingsWith the single lateral plate, the distal fragment experienced a resultant displacement of 0.40mm under cantilever bending and 0.61mm under compression (13% and 20% respectively of fracture gap width). With the bilateral plates, fracture gap motion was significantly reduced to 0.13mm under bending and compression (4.3% of the fracture gap). InterpretationOur results indicate that a bilateral plating method is capable of improving stabilization of periprosthetic fractures compared to the traditional lateral plating technique.

HyperCube: A Small Lensless Position Sensing Device for the Tracking of Flickering Infrared LEDs

An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs) with an accuracy much greater than the one dictated by the pixel pitch. With a size of only 1 cm3 and a mass of only 0.33 g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. Only three photosensors are placed on each side of the cubic configuration of the sensing device, making this sensor very inexpensive and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at a high frequency (>1 kHz) with a precision of 0.5°. The minimalistic design in terms of small size, low mass and low power consumption of this visual sensor makes it suitable for many applications in the field of the cooperative flight of unmanned aerial vehicles and, more generally, robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the flickering infrared markers.

Effects of Unstable Conditions on Kinematics and Performance Variables in Young Handball Players.

The execution variability and outcomes found in throwing actions have received special attention in numerous studies in recent years. The aim of this study was to analyze the effect of an unstable condition on velocity, accuracy and kinematics of movement in the seven metres throw in handball. Twenty-five young handball players took part in an experiment, throwing towards a target on a stable and an unstable surface. Each participant performed 32 throws, 16 for each situation. Linear variability of the dominant hand was assessed by 3D Motion Tracking. A radar sports gun was used to record the velocity of the ball and the throws were video recorded to establish their accuracy. Results showed significant decreases in throwing velocity in unstable conditions, but these did not significantly affect the accuracy achieved in performance. Differences were also found in movement kinematics between the two throwing conditions and relationships were found between kinematics, velocity and accuracy.

Characterization of right ventricular remodeling in pulmonary hypertension associated with patient outcomes by 3-dimensional wall motion tracking echocardiography.

Adverse right ventricular (RV) remodeling has significant prognostic and therapeutic implications to patients with pulmonary hypertension (PH). However, differentiating RV adaption from adverse remodeling associated with poor outcomes is difficult. We hypothesized that novel 3-dimensional (3D) wall motion tracking echocardiography can differentiate morphological features of RV adaption from adverse remodeling heralding an unfavorable short-term prognosis in patients with PH. We studied 112 subjects: 92 patients with PH and 20 normal controls with 3D wall motion tracking for RV end-systolic volume index (ESVi), RV ejection fraction (EF), and RV global area strain. Patients with PH also had invasive hemodynamic measurements. Pressure-volume relations classified patients with PH into 3 groups, such as RV adapted, RV adapted-remodeled, and RV adverse-remodeled. The predefined combined end point was PH-related hospitalization, death, or lung surgery (lung transplantation or pulmonary endarterectomy) during 6 months. The 92 patients with PH had significantly larger RV volumes, lower RVEF and global area strain than normal controls as expected. Patients with PH classified as RV adapted (ESVi, ≤72 mL/m(2)) had a more favorable clinical outcome than those classified as RV adapted-remodeled (ESVi, 73-113 mL/m(2)) or RV adverse-remodeled (ESVi, ≥114 mL/m(2)): hazard ratio, 0.15; 95% confidence intervals, 0.07 to 0.39; P<0.0001. RV adverse-remodeled patients (ESVi, ≥114 mL/m(2)) had worse short-term outcome than the RV adapted-remodeled patients: hazard ratio, 2.2; 95% confidence interval, 0.91 to 5.39; P=0.04. Quantitative 3D echocardiography in patients with PH demonstrated morphological subsets of RV adaption and remodeling associated with clinical outcomes.

Social categorization and cooperation in motor joint action: evidence for a joint end-state comfort.

The present study investigated to what extent group membership affects an actor's representation of their partner's task in cooperative joint action. Participants performed a joint pick-and-place task in a naturalistic, breakfast-table-like paradigm which allowed the demonstration of varying degrees of cooperation. Participants transported a wooden cup from one end of a table to the other, with one actor moving it to an intermediate position from where their partner transported it to a goal position. Hand and finger movements were recorded via 3D motion tracking to assess actors' cooperative behavior. Before the joint action task was performed, participants were categorized as belonging to the same or to different groups, supposedly based on an assessment of their cognitive processing styles. Results showed that the orientation of the actors' fingers when picking up the cup was affected by its required angle at the goal position. When placing the cup at the intermediate position, most actors adapted the rotation of the cup's handle to the joint action goal, thereby facilitating the partner's subsequent movement. Male actors demonstrated such cooperative behavior only when performing the task together with an ingroup partner, while female actors demonstrated cooperative behavior irrespective of social categorization. These results suggest that actors tend to represent a partner's end-state comfort and integrate it into their own movement planning in cooperative joint action. However, social factors like group membership may modulate this tendency.

Kinematic-based Markerless Human Tracking in 3D Probabilistic Occupancy Grids

Markerless human motion tracking can be employed in many applications such as automatic surveillance, motion capture, human-machine interface and activity recognition. This problem has been extensively studied in the computer vision research community in the last years. In this context, the present paper presents an approach for 3D markerless human motion tracking based on a skeletal kinematic model of the human body. This method is applied over a 3D probabilistic occupancy grid of the environment, which is constructed by means of a Bayesian fusion of images from multiple synchronized sensoring cameras. Although the use of kinematic models in 3D human tracking is widely employed, its use over 3D probabilistic occupancy grids still was not vastly investigated in the literature. The experiments were performed using a public dataset with video sequences of people in motion. The results show that the method is capable of dealing adequately with the 3D markerless human motion tracking problem.

Inertial measures of motion for clinical biomechanics: comparative assessment of accuracy under controlled conditions - changes in accuracy over time.

BackgroundInterest in 3D inertial motion tracking devices (AHRS) has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven’t been extensively documented. The objectives of this study are: 1) to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2) to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time.MethodsThis study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT) and 12 minutes multiple dynamic phases motion trials (12MDP). Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials.FindingsBoth absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase.InterpretationThe variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame.ConclusionsMean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their full potential in capturing clinical outcomes.

Evidence for a general stiffening motor control pattern in neck pain: a cross sectional study.

BackgroundNeck pain is associated with several alterations in neck motion and motor control. Previous studies have investigated single constructs of neck motor control, while few have applied a comprehensive set of tests to investigate cervical motor control. This comparative cross- sectional study aimed to investigate different motor control constructs in neck pain patients and healthy controls.MethodsA total of 166 subjects participated in the study, 91 healthy controls (HC) and 75 neck pain patients (NP) with long-lasting moderate to severe neck pain. Neck flexibility, proprioception, head steadiness, trajectory movement control, and postural sway were assessed using a 3D motion tracking system (Liberty). The different constructs of neck motion and motor control were based on tests used in previous studies.ResultsNeck flexibility was lower in NP compared to HC, indicated by reduced cervical ROM and conjunct motion. Movement velocity was slower in NP compared to HC. Tests of head steadiness showed a stiffer movement pattern in NP compared to HC, indicated by lower head angular velocity. NP patients departed less from a predictable trajectory movement pattern (figure of eight) compared to healthy controls, but there was no difference for unpredictable movement patterns (the Fly test). No differences were found for postural sway in standing with eyes open and eyes closed. However, NP patients had significantly larger postural sway when standing on a balance pad. Proprioception did not differ between the groups. Largest effect sizes (ES) were found for neck flexibility (ES range: 0.2- 0.8) and head steadiness (ES range: 1.3- 2.0). Neck flexibility was the only construct that showed a significant association with current neck pain, while peak velocity was the only variable that showed a significant association with kinesiophobia.ConclusionsNP patients showed an overall stiffer and more rigid neck motor control pattern compared to HC, indicated by lower neck flexibility, slower movement velocity, increased head steadiness and more rigid trajectory head motion patterns. Only neck flexibility showed a significant association with clinical features in NP patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0517-2) contains supplementary material, which is available to authorized users.

3D Pose Tracking with Multi-Template Warping and SIFT Correspondences

Template warping is a popular technique in vision-based 3D motion tracking and 3D pose estimation due to its flexibility of being applicable to monocular video sequences. However, the method suffers from two major limitations that hamper its successful use in practice. First, it requires the camera to be calibrated prior to applying the method. Second, it may fail to provide good results if the inter-frame displacements are too large. To overcome the first problem, we propose to estimate the unknown focal length of the camera from several initial frames by an iterative optimization process. To alleviate the second problem, we propose a tracking method based on combining complementary information provided by dense optical flow and tracked scale-invariant feature transform (SIFT) features. While optical flow is good for small displacements and provides accurate local information, tracked SIFT features are better at handling larger displacements or global transformations. To combine these two pieces of complementary information, we introduce a forgetting factor to bootstrap the 3D pose estimates provided by SIFT features, and refine the final results using optical flow. Experiments are performed on three public databases, i.e., the Biwi Head Pose dataset, the BU dataset, and the McGill Faces datasets. The results illustrate that the proposed solution provides more accurate results than baseline methods that rely solely on either template warping or SIFT features. In addition, the approach can be applied in a larger variety of scenarios, due to circumventing the need for camera calibration, thus providing a more flexible solution to the problem than existing methods.

Differences in knee flexion between the Genium and C-Leg microprocessor knees while walking on level ground and ramps

BackgroundMicroprocessor knees have improved the gait and functional abilities of persons with transfemoral amputation. The Genium prosthetic knee offers an advanced sensor and control system designed to decrease impairment by: allowing greater stance phase flexion, easing transitions between gait phases, and compensating for changes in terrain. The aim of this study was to determine differences between the knee flexion angle of persons using the Genium knee, the C-Leg knee, and non-amputee controls; and to evaluate the impact the prostheses on gait and level of impairment of the user. MethodsThis study used a randomized experimental crossover of persons with transfemoral amputation using the Genium and C-Leg microprocessor knees (n=25), with an observational sample of non-amputee controls (n=5). Gait analysis by 3D motion tracking of subjects ambulating at different speeds on level ground and on 5° and 10° ramps was completed. FindingsUse of the Genium resulted in a significant increase in peak knee flexion for swing (5°, p<0.01, d=0.34) and stance (2°, p<0.01, d=0.19) phases relative to C-Leg use. There was a high degree of variability between subjects, and significant differences still remain between the Genium group and the control group's knee flexion angles for most speeds and slopes. InterpretationThe Genium knee generally increases flexion in swing and stance, potentially decreasing the level of impairment for persons with transfemoral amputation. This study demonstrates functional differences between the C-Leg and Genium knees to help prosthetists determine if the Genium will provide functional benefits to individual patients.

Parallel computing on graphics processing units and heterogeneous platforms

Parallel computing on graphics processing units and heterogeneous platforms

3D Human motion tracking by exemplar-based conditional particle filter

3D human motion tracking has received increasing attention in recent years due to its broad applications. Among various 3D human motion tracking methods, the particle filter is regarded as one of the most effective algorithms. However, there are still several limitations of current particle filter approaches such as low prediction accuracy and sensitivity to discontinuous motion caused by low frame rate or sudden change of human motion velocity. Targeting such problems, this paper presents a full-body human motion tracking system by proposing exemplar-based conditional particle filter (EC-PF) for monocular camera. By introducing a conditional term with respect to exemplars and image data, dynamic model is approximated and used to predict current states of particles in prediction phase. In update phase, weights of particles are refined by matching images with projected human model using a set of features.This method retains advantages of classic particle filters while increases prediction accuracy by replacing the smooth motion model with exemplars-based dynamic model which constrains evolved particles within an area closer to true state. Therefore, tracking robustness to discontinuous motion is improved such as under conditions of sudden change in motion velocity or using low-frame rate cameras. To verify the effectiveness and efficiency of the proposed algorithm, a variety of datasets are selected for testing and the results are also compared with the state-of-the-art methods in this domain.

Effect of passive polarizing three-dimensional displays on surgical performance for experienced laparoscopic surgeons.

Although the potential benefits of stereoscopic laparoscopy have been recognized for years, the technology has not been adopted because of poor operator tolerance. Passive polarizing projection systems, which have revolutionized three-dimensional (3D) cinema, are now being trialled in surgery. This study was designed to see whether this technology resulted in significant performance benefits for skilled laparoscopists. Four validated laparoscopic skills tasks, each with ten repetitions, were performed by 20 experienced laparoscopic surgeons, in both two-dimensional (2D) and 3D conditions. The primary outcome measure was the performance error rate; secondary outcome measures were time for task completion, 3D motion tracking (path length, motion smoothness and grasping frequency) and workload dimension ratings of the National Aeronautics and Space Administration (NASA) Task Load Index. Surgeons demonstrated a 62 per cent reduction in the median number of errors and a 35 per cent reduction in median performance time when using the passive polarizing 3D display compared with the 2D display. There was a significant 15 per cent reduction in median instrument path length, an enhancement of median motion smoothness, and a 15 per cent decrease in grasper frequency with the 3D display. Participants reported significant reductions in subjective workload dimension ratings of the NASA Task Load Index following use of the 3D displays. Passive polarizing 3D displays improved both the performance of experienced surgeons in a simulated setting and surgeon perception of the operative field. Although it has been argued that the experience of skilled laparoscopic surgeons compensates fully for the loss of stereopsis, this study indicates that this is not the case. Surgical relevance The potential benefits of stereoscopic laparoscopy have been known for years, but the technology has not been adopted because of poor operator tolerance. The first laparoscopic operation was carried out using a prototype passive polarizing laparoscopic system in 2010. This is new three-dimensional (3D) technology offers a real option for 3D laparoscopic surgery where previous systems have failed. This study is the first to have been carried out using this technology. It is essential that new technologies are adopted only when there is robust evidence to support their use. Currently, there are concerns about the use of robotic technologies and whether advantages exist for patient care. If there are advantages, 3D must be playing a significant role. If so, perhaps the technology under investigation here offers potential to a greater spectrum of surgeons, as well as being a more affordable option.

Real‐time multiview human pose tracking using graphics processing unit‐accelerated particle swarm optimization

SummaryThis paper describes how to achieve real‐time tracking of 3D human motion using multiview images and graphics processing unit (GPU)‐accelerated particle swarm optimization. The tracking involves configuring the 3D human model in the pose described by each particle and then rasterizing it in each 2D plane. The Compute Unified Device Architecture threads rasterize the columns of the triangles and perform the summing of the fitness values of pixels belonging to the processed columns. Such a parallel particle swarm optimization (PSO) exhibits the level of parallelism that allows us to effectively utilize the GPU resources. Image acquisition and image processing are multithreaded and run on CPU in parallel with PSO‐based searching for the best pose. Owing to such task decomposition, the tracking of the full human body can be performed at rates of 12 frames per second. For a PSO consisting of 1000 particles and executing 10 iterations, the GPU achieves an average speedup of 12 over the CPU. Using marker‐less motion capture system consisting of four calibrated and synchronized cameras, the efficiency comparisons were conducted on four CPU cores and four GTX GPUs on two cards. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Kinect Fusion improvement using depth camera calibration

Abstract. Scene's 3D modelling, gesture recognition and motion tracking are fields in rapid and continuous development which have caused growing demand on interactivity in video-game and e-entertainment market. Starting from the idea of creating a sensor that allows users to play without having to hold any remote controller, the Microsoft Kinect device was created. The Kinect has always attract researchers in different fields, from robotics to Computer Vision (CV) and biomedical engineering as well as third-party communities that have released several Software Development Kit (SDK) versions for Kinect in order to use it not only as a game device but as measurement system. Microsoft Kinect Fusion control libraries (firstly released in March 2013) allow using the device as a 3D scanning and produce meshed polygonal of a static scene just moving the Kinect around. A drawback of this sensor is the geometric quality of the delivered data and the low repeatability. For this reason the authors carried out some investigation in order to evaluate the accuracy and repeatability of the depth measured delivered by the Kinect. The paper will present a throughout calibration analysis of the Kinect imaging sensor, with the aim of establishing the accuracy and precision of the delivered information: a straightforward calibration of the depth sensor in presented and then the 3D data are correct accordingly. Integrating the depth correction algorithm and correcting the IR camera interior and exterior orientation parameters, the Fusion Libraries are corrected and a new reconstruction software is created to produce more accurate models.

Joint Audiovisual Hidden Semi-Markov Model-Based Speech Synthesis

This paper investigates joint speaker-dependent audiovisual Hidden Semi-Markov Models (HSMM) where the visual models produce a sequence of 3D motion tracking data that is used to animate a talking head and the acoustic models are used for speech synthesis. Different acoustic, visual, and joint audiovisual models for four different Austrian German speakers were trained and we show that the joint models perform better compared to other approaches in terms of synchronization quality of the synthesized visual speech. In addition, a detailed analysis of the acoustic and visual alignment is provided for the different models. Importantly, the joint audiovisual modeling does not decrease the acoustic synthetic speech quality compared to acoustic-only modeling so that there is a clear advantage in the common duration model of the joint audiovisual modeling approach that is used for synchronizing acoustic and visual parameter sequences. Finally, it provides a model that integrates the visual and acoustic speech dynamics.

MP14-13 THE FLUORO-LESS C-ARM PERCUTANEOUS ACCESS TRAINER

You have accessJournal of UrologyTechnology & Instruments: Surgical Education & Skills Assessment II1 Apr 2014MP14-13 THE FLUORO-LESS C-ARM PERCUTANEOUS ACCESS TRAINER Domenico Veneziano, Arthur Smith, Troy Reihsen, Jason Speich, and Robert Sweet Domenico VenezianoDomenico Veneziano More articles by this author , Arthur SmithArthur Smith More articles by this author , Troy ReihsenTroy Reihsen More articles by this author , Jason SpeichJason Speich More articles by this author , and Robert SweetRobert Sweet More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.641AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Achieving proper renal access is one of the most challenging skill-sets for PCNL. Parallax of the proper calyx with c-arm is a core learning objective. Existing training systems use virtual reality(VR) or fluoro-assisted biologic and synthetic models. VR models have limitations and are expensive and fluoroscopy is impractical and is associated with unnecessary exposure to radiation. We report the development and initial validation of a fluoro-less percutaneous renal access trainer. METHODS A mini C-arm was designed and 3D printed. Two videocameras were mounted on the anterior and posterior portion of the C. The C was designed to tilt and rainbow. A clear flank model was created with a silicon material with a cast of a University of Minnesota SimPORTAL calyceal model in it filled with fluid. The silicon model has been then covered with a "blue screen" skin-like, colored material and provided with a physical reproduction of the 10th-12th ribs. The two cameras have been connected to a computer for image processing to produce the final on-screen image. RESULTS The C-arm navigation trainer has face and content validity for training percutaneous access. It does so successfully without radiation exposure. The novel double camera system and the image processing software were able to obtain visual information enough to accomplish correctly the training tasks, without expensive additional 3d motion tracking technologies. CONCLUSIONS The fluoroscopy-less C-arm navigation trainer accurately replicates the functions of a real X-ray system, without any radiation exposure related issues, regardless the time it takes to complete the training sessions. The usability of a perc model, as well as of any other specifically designed anatomical silicon models, make it a low cost, feasible instrument for training. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e173 Peer Review Report Advertisement Copyright & Permissions© 2014MetricsAuthor Information Domenico Veneziano More articles by this author Arthur Smith More articles by this author Troy Reihsen More articles by this author Jason Speich More articles by this author Robert Sweet More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

3D facial motion tracking by combining online appearance model and cylinder head model in particle filtering

A 3D facial motion tracking approach has been proposed based on the incorporation of online appearance model (OAM) and cylinder head model (CHM) in the framework of particle filtering. 1) For the construction of OAM, multi-measurements are infused to reduce the influence of lighting and person dependence. 2) The global motion acquired from CHM fitting is set as the initialization of OAM fitting, and the fitting result is set as the initialization of CHM in the next frame. 3) Motion filtering is applied with particle filter combined with local optimization and improved resampling. Objective between subjects evaluations show that our approach is fit to track facial motions.

IGRT/ART phantom with programmable independent rib cage and tumor motion

This paper describes the design and experimental evaluation of the Methods and Advanced Equipment for Simulation and Treatment in Radiation Oncology (MAESTRO) thorax phantom, a new anthropomorphic moving ribcage combined with a 3D tumor positioning system to move target inserts within static lungs. The new rib cage design is described and its motion is evaluated using Vicon Nexus, a commercial 3D motion tracking system. CT studies at inhale and exhale position are used to study the effect of rib motion and tissue equivalence. The 3D target positioning system and the rib cage have millimetre accuracy. Each axis of motion can reproduce given trajectories from files or individually programmed sinusoidal motion in terms of amplitude, period, and phase shift. The maximum rib motion ranges from 7 to 20 mm SI and from 0.3 to 3.7 mm AP with LR motion less than 1 mm. The repeatability between cycles is within 0.16 mm root mean square error. The agreement between CT electron and mass density for skin, ribcage, spine hard and inner bone as well as cartilage is within 3%. The MAESTRO phantom is a useful research tool that produces programmable 3D rib motions which can be synchronized with 3D internal target motion. The easily accessible static lungs enable the use of a wide range of inserts or can be filled with lung tissue equivalent and deformed using the target motion system.