Marker Motion Research Articles

Changes in Gait Pattern During Smartphone and Tablet Use

Objectives: There exists no study concerning gait pattern while engaging in dual-task activities on different sizes of mobile devices. The present study aimed to compare gait patterns during normal walking, walking with smartphone use, and walking with tablet use. Methods: Seventeen healthy female participants with an age range of 19-24 years (Mean±SD age: 20.29±1.61 years, weight: 49.82±4.46 kg, height: 156.59±4.87 cm, body mass index: 20.47±0.84 kg/m2, and leg length: 81.35±3.79 cm.) participated in the present research. The study subjects were requested to walk for 10 meters under the following conditions: normal walking; walking while typing a text message with a smartphone, and walking while typing a text message with a tablet. The Vicon® Three-Dimensional (3D) motion analysis recorded the motion of reflective markers attached to the study participant’s body. Gait parameters (step length, stride length, step time, stride time, step width, velocity, and cadence) were compared between the explored walking conditions. Results: The gait parameter of normal walking, compared with walking during smartphone use as well as tablet use were significantly different in the gait pattern (P<0.05). Using either a smartphone or tablet during walking presented decreased step length for legs, gait velocity, and cadence. However, there was an increase in the right leg’s step time and stride time. Moreover, there was no significant difference in gait patterns between walking during smartphone use and walking during tablet use (P>0.05). Discussion: Changes in gait pattern during walking while typing a text message with either a smartphone or tablet may lead to greater attention and concentration required to type the message; such actions resulted in decreased gait speed and step length.

The use of tumour markers in oesophageal cancer to quantify setup errors and baseline shifts during treatment

PurposeTo prospectively evaluate the feasibility of solid gold marker placement in oesophageal cancer patients and to quantify inter-fractional and intra-fractional (baseline shift) marker motion during radiation treatment. Radiotherapy target margins and matching strategies were investigated. Materials/methodsThirty-four markers were implanted by echo-endoscopy in 10 patients. Patients received a planning 4D CT, daily pre-treatment cone-beam CT (CBCT) and a post-treatment CBCT for at least five fractions. For fractions with both pre- and post-treatment CBCT, marker displacement between planning CT and pre-treatment CBCT (inter-fractional) and between pre-treatment and post-treatment CBCT (intra-fractional; only for fractions without rotational treatment couch correction) were calculated in left–right (LR), cranio-caudal (CC) and anterior-posterior (AP) direction after bony-anatomy and soft-tissue matching. Systematic/random setup errors were estimated; treatment margins were calculated. ResultsNo serious adverse events occurred. Twenty-three (67.6%) markers were visible during radiotherapy (n = 3 middle oesophagus, n = 16 distal oesophagus, n = 4 proximal stomach). Margins for inter-fractional displacement after bony-anatomy match depended on the localisation of the primary tumour and were 11.2 mm (LR), 16.4 mm (CC) and 8.2 mm (AP) for distal markers. Soft-tissue matching reduced the CC margin for these markers (16.4 mm to 10.5 mm). The mean intra-fractional shift of 12 distal markers was 0.4 mm (LR), 2.3 mm (CC) and 0.7 mm (AP). Inclusion of this shift resulted in treatment margins for distal markers of 12.8 mm (LR), 17.3 mm (CC) and 10.4 mm (AP) after bony-anatomy matching and 12.4 mm (LR), 11.4 mm (CC) and 9.7 mm (AP) after soft-tissue matching. ConclusionThis study demonstrated that the implantation of gold markers was safe, albeit less stable compared to other marker types. Inter-fractional motion was largest cranio-caudally for markers in the distal oesophagus, which was reduced after soft-tissue compared to bony-anatomy matching. The impact of intra-fractional baseline shifts on margin calculation was rather small.

A novel simplified biomechanical assessment of the heel pad during foot plantarflexion.

The heel pad (HP) which is located below the calcaneus comprises a composition of morphometrical and morphological arrangements of soft tissues that are influenced by factors such as gender, age and obesity. It is well known that HP pain and Achilles tendonitis consist of discomfort, pain and swelling symptoms that usually develop from excessive physical activities such as walking, jumping and running. The purpose of this study was to develop biomechanical techniques to evaluate the function and characteristics of the HP. Ten healthy participants (five males and five females) participated in this laboratory-based study, each performing a two-footed heel raise to mimic the toe-off phase during human locomotion. Twenty-six (3 mm) retroreflective markers were attached to the left and right heels (thirteen markers on each heel). Kinematic data was captured using three-dimensional motion analysis cameras synchronised with force plates. Descriptive and multivariate statistical tests were used in this study. In addition, a biomechanical technique that utilises only six markers from 26 markers to assess HP deformation and function has been developed and used in this study. Overall HP displacement was significantly higher in males on the most lateral part of the right heel (p < 0.05). No significant differences were evident when comparing the non-dominant and dominant heels during the baseline, unloading and loading phases (p > 0.05). Findings from this study suggested that biomechanical outputs expressed as derivatives from tracked HP marker movements can morphologically and morphometrically characterise HP soft tissue deformation changes. The outcome of this study highlights the importance of 3D motion analysis being used as a potential prospective intervention to quantify the function / characteristics of the heel pad soft tissues.

The role of Imperialist Competitive Algorithm in motion dataset optimization for ANFIS prediction model at external surrogates radiotherapy

Introduction: At radiotherapy with external surrogates, a consistent prediction model is utilized to estimate tumor location as model output on the basis of external markers motion dataset as model input. In this study, Imperialist Competitive Algorithm is proposed to process and optimize external markers motion dataset for prediction model. The simplicity of prediction model based on the proposed algorithm results lesser targeting error with the least computational time. Materials and methods: a prediction model based on Adaptive Neuro-Fuzzy Inference System is utilized with database of 20 patients treated with Cyberknife Synchrony system. In order to assess the effect of proposed data optimization algorithm, two methods were considered. The prediction model is used with and without implementing Imperialist Competitive Algorithm. Then, targeting error of ANFIS model at these two methods is compared, quantitatively. Results: By implementing the proposed algorithm, the performance accuracy of ANFIS prediction model is remarkably improved by eliminating unnecessary and noisy inputs. Moreover, model simplicity factor could highly reduce model computational time this is required for clinical practice. Conclusion: Imperialist Competitive Algorithm was proposed as data optimization algorithm on motion dataset of patients who are treated with external surrogate’s radiotherapy. The proposed algorithm could highly optimize the external markers motion dataset as input of ANFIS model for estimating tumor position by selecting enough data points with high degree of importance. Final results show an improvement of targeting accuracy of prediction using proposed strategy and also significant reduction at model computational time.

A Complex Convolution Kernel-Based Optical Displacement Sensor

During the last decade, a variety of optical displacement measurement techniques have been developed, commercialized and widely used. This paper presents a new type of optical displacement sensor that improves on the prior art with higher sub-pixel resolution, better accuracy, and better computation efficiency. The Complex Convolution Kernel-Based Optical Sensor (KBOS) developed in this paper leverages the phase-magnitude representation of a complex valued kernel function to achieve a superior optical displacement sensor for 2D motion measurements. The sensor’s performance and properties are quantified in terms of its ability to compute the marker motions. Evaluation of this metric will explain how the sensor is able to achieve superior performance over the state of the art. The design is then validated with a set of experiments over a range of operating conditions to demonstrate the effectiveness of the approach over other existing displacement measurement techniques. Finally, the sensor’s capability is compared qualitatively against other state of the art optical displacement sensors found in the literature. The sensor is shown to possess a subpixel resolution of between 1/100 and 1/2500 of a pixel depending upon spatial sampling density. The sensors dynamic range was investigated and shown to be only limited by the camera sampling speeds.

Assessment of Internal and External Surrogates for Lung Stereotactic Body Radiation Therapy

Purpose: To evaluate internal (lung, heart and diaphragm) and external (nine glass marbles) marker motion in correlation with lung tumor motion, to determine potential surrogate for respiratory gating radiation therapy (RGRT) depending on tumor localization, upper lobe (UL) vs lower lobe (LL).Methods: This study included 58 patients (34 male and 24 female) with small lung cancer (≤ 5cm), who underwent Stereotactic Body Radiation Therapy (SBRT). All patients were scanned and contoured in all ten phases (Varian Eclipse 13.7) after four-dimensional computed tomography simulation (4D-CT). The motion of internal markers and external markers were analyzed and correlated with tumor motion. The Pearson correlation coefficient (PCC) was used to evaluate the correlation between internal and external marker motion with tumor motion. Results: The median (range) values of tumor motion were 3.2 (0.6-11.0) vs 8.6 (4.0-24.0) mm in the UL vs LL. The median (range) values of organs motion and PCC comparing UL vs LL were: 2.0 (0.3-9.1) vs 6.0 (2.8-13.9) mm and 0.46 (0.30-0.95) vs 0.79 (0.50-0.94) to the lung; 11.9 (2.5-16.3) vs 12.5 (5.0-22.5) mm and 0.68 (0.11-0.93) vs 0.89 (0.30-0.99) to the diaphragm; and 3.9 (2.5-6.3) vs 7.6 (4.5-8.6) mm and 0.49 (0.20-0.70) vs 0.59 (0.36-0.83) to the heart. The external marker motion and correlation coefficient for UL and LL were 2.5 (0.9-7.4) vs 2.3 (1.0-5.9) mm and 0.54 (0.09-0.96) vs 0.73 (0.27-0.94).Conclusion: Lung and diaphragm motion correlate better with tumor motion than the external marker. Diaphragm motion can be an excellent indicator for treatment based on RGRT.

Validation of a Bar Linkage Model for Joint Angle Estimation during Cycling

Measuring lower extremity joint angles during cycling is interesting to derive joint loading from contact forces at the pedals and to determine the cause of cycling injuries. Traditionally, joint angles are determined in a stationary setup with high-resolution cameras that track marker movement in a lab environment. Alternatively, joint angles can be estimated mathematically in-situ: the lower extremities, bicycle frame and pedal arms are presented as a 5 bar linkage system which is fully defined by the lower extremity segment lengths, seat height and pedal position. As most instrumented pedals for power measurements include pedal orientation measurements, the bar linkage system demands no special equipment to derive joint loadings from pedal loads. The aim of this study is to validate the bar linkage system for joint angle estimation in the sagittal plane during in-situ cycling. Ten subjects cycled on a stationary bike while the hip, knee and ankle angles were measured with a Vicon optoelectronic motion capture system and simultaneously calculated with the bar linkage system. The results were averaged to subject-specific and method-specific ensemble average curves in the function of the phase in the pedal cycle and compared by a correlation analysis, Bland Altman plot, and Spm1D paired T-test. The hip and knee angle estimation of the bar linkage system showed no statistically significant difference from the optoelectronic system. Moreover, the ankle showed a statistically significant difference in the last half of the recovery phase of the pedal cycle. As the difference was maximally 3°, it has no clinical significance when deriving joint loading from contact forces at the pedal.

Achilles tendon moment arms are similar when computed using a single fixed axis versus a moving instantaneous helical axis

Accurate location of the axis of ankle rotation is critical to in vivo estimates of Achilles tendon moment arm. Here we investigated how the plantarflexion moment arm of the Achilles tendon is affected by using an instantaneous helical axis that moves with ankle motion as opposed to a single fixed joint axis that approximates the average axis of rotation. Twenty young healthy adults performed a series of weightbearing cyclical plantar- and dorsi-flexion motions. Motion analysis tracked the motions of markers placed on the foot and shank and also tracked an ultrasound probe imaging the Achilles tendon. Differences in ATma between the methods were investigated using a two-way repeated-measures ANOVA with factors of joint angle (+5°, 0°, −5°, −10°, −15°) and method (instantaneous helical axes, fixed axis). Moment arms computed between the two methods were moderately to strongly correlated, especially in the mid-range of motion (for 0° to 10° plantarflexion, all r2 > 0.619 and all p < 0.004). The two methods produced Achilles tendon moment arms that were comparable and not significantly different except in the most dorsiflexed position, when they differed on average by 9.35 ± 3.23 mm (p = 0.001). Our results suggest that either approach for locating the axis of ankle rotation would be appropriate for the purpose of estimating ATma, but that a fixed axis may be preferable because it is applicable over a greater range of ankle motion.

Marker-free optical stereo motion tracking for in-bore MRI and PET-MRI application.

Prospective motion correction is arguably the "silver bullet" solution for magnetic resonance imaging (MRI) studies impacted by motion, applicable to almost any pulse sequence and immune from the spin history artifacts introduced by a moving object. In prospective motion correction, the magnetic field gradients and radio frequency waveforms are adjusted in real time in response to measured head motion so as to maintain the head in a stationary reference frame relative to the scanner. Vital for this approach are accurate and rapidly sampled head pose measurements, which may be obtained optically using cameras. However, most optical methods are limited by the need to attach physical markers to the skin, which leads to decoupling of head and marker motion and reduces the effectiveness of correction. In this work we investigate the feasibility and initial performance of a stereo-optical motion tracking method which does not require any attached markers. The method relies on detecting distinctive natural features or amplified features (using skin stamps) directly on the forehead in multiple camera views, and then deriving pose estimates via a 3D-2D registration between the skin features and a database of forehead landmarks. To demonstrate the feasibility and potential accuracy of the marker-free method for discrete (step-wise) head motion, we performed out-of-bore and in-bore experiments using robotically and manually controlled phantoms in addition to in-bore testing on human volunteers. We also developed a convenient out-of-bore test bed to benchmark and optimize the motion tracking performance. For out-of-bore phantom tests, the pose estimation accuracy (compared to robotic ground truth) was 0.14mm and 0.23degrees for incremental translation and rotation, respectively. For arbitrary motion, the pose accuracy obtained using the smallest forehead feature patch was equivalent to 0.21±0.11mm positional accuracy in the striatum. For in-bore phantom experiments, the accuracy of rigid-body motion parameters (compared to wireless MR-sensitive markers) was 0.08-0.41±0.18mm/0.05-0.3±0.12deg and 0.14-0.16±0.12mm/0.08-0.17±0.08deg for the small and large feature patches, respectively. In vivo results in human volunteers indicated sub-millimeter and sub-degree pose accuracy for all rotations and translations except the depth direction (max error 1.8mm) when compared to a registration-based approach. In both bench-top and in vivo experiments we demonstrate the feasibility of using very small feature patches directly on the skin to obtain high accuracy head pose measurements needed for motion-correction in MRI brain studies. The optical technique uses in-bore cameras and is consistent with the limited visibility of the forehead afforded by head coils used in brain imaging. Future work will focus on optimization of the technique and demonstration in prospective motion correction.

Motion tracking of low‐activity fiducial markers using adaptive region of interest with list‐mode positron emission tomography

Motion compensated positron emission tomography (PET) imaging requires detecting and monitoring of patient body motion. We developed a semiautomatic list-mode method to track the three-dimensional (3D) motion of fiducial positron-emitting markers during PET imaging. A previously developed motion tracking method using positron-emitting markers (PeTrack) was enhanced to work with PET imaging. A novel combination of filtering methods was developed to reject physiological tracer background, which would drown out the events from the marker if unfiltered. The most critical filter rejects events whose line-of-response (LOR) is outside an adaptive region of interest (ADROI). The size of ROI was optimized by exploiting the distinct differences between the distributions of events from background and marker. The ADROI PeTrack method was evaluated with Monte Carlo and phantom studies. A 92.5-kBq Na marker moving sinusoidally in 3D was simulated with Monte Carlo methods. The simulated events were combined with list-mode data from cardiac PET imaging patients to evaluate the performance of the tracking. In phantom studies, three Na markers were placed on a dynamic torso phantom with an initial activity of 680MBq of Rb in its cardiac insert. The motion of the markers was tracked while the phantom simulated various types of patient motion. Motion correction on an event-by-event basis of the list-mode data was then applied and images were reconstructed. Simulation results show that the background rejection methods can significantly suppress the tracer background and increase the fraction of marker events by a factor of up to 2500. A 92.5-kBq marker can be tracked in 3D at a frequency of 2.0Hz with an accuracy of 0.8mm and a precision of 0.3mm. The phantom study experimentally confirms that the algorithm can track various types of motion. The relative accuracy of the experimental tracking is 0.26±0.14mm. Motion-corrected images from the phantom study show reduced blurring. An algorithm and background rejection methods were developed that can track the 3D motion of low-activity positron-emitting markers during PET imaging. The motion information may be used for motion-compensated PET imaging.

Brain Strain from Motion of Sparse Markers.

Brain strain secondary to head impact or inertial loading is closely associated with pathologic observations in the brain. The only experimental brain strain dataset under loadings close to traumatic levels was calculated by imposing the experimentally measured motion of markers embedded in the brain to an auxiliary model formed by triad elements (Hardy et al., 2007). However, fidelity of the calculated strain as well as the suitability of using triad elements for three-dimensional (3D) strain estimation remains to be verified. Therefore, this study proposes to use tetrahedron elements as a new approach to estimate the brain strain. Fidelity of this newly-proposed approach along with the previous triad-based approach is evaluated with the aid of three independently-developed finite element (FE) head models by numerically replicating the experimental impacts and strain estimation procedures. Strain in the preselected brain elements obtained from the whole head simulation exhibits good correlation with its tetra estimation and exceeds its triad estimation, indicating that the tetra approach more accurately estimates the strain in the preselected region. The newly calculated brain strain curves using tetra elements provide better approximations for the 3D experimental brain deformation and can be used for strain validation of FE models of human head.

СИСТЕМИ ЗАХОПЛЕННЯ РУХУ В ДОДАНІЙ РЕАЛЬНОСТІ: РІЗНОВИДИ ТА СПЕЦИФІКА ЇХ ЗАСТОСУВАННЯ У ПРАКТИЦІ ПРОМОЦІЙНИХ КОМУНІКАЦІЙ

&lt;div&gt;&lt;p&gt;&lt;em&gt;In this study there were identified the main varieties of existing motion capture systems (mocap) that can be used primarily to create three-dimensional animation for augmented reality; as well as established their specific features, and also demonstrated the examples of the practical use of certain types of such systems in promotional communications.&lt;/em&gt;&lt;/p&gt;&lt;/div&gt;&lt;p&gt;&lt;em&gt;This study unleashes the specificity of the functioning of non-marker and all types of marker motion capture systems – optical (optically passive and optically active, including «performance capture» as well as hybrid) and non-optical (acoustic, magnetic, mechanical and inertial).&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;There were analyzed two practical promotional cases: the American social PR project «Love Has No Labels» and the Japanese commercial brand «ZozoTown» («ZozoSuit»).&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;It has been found that in the practice of promotional communications inertial-type mocap systems with full magnetic interference are most actively used, since they can be used directly during mass AR-actions, primarily due to their portability and ability to function in a limited space.&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;It has also been revealed that AR-actions using motion capture systems are conducted primarily to create positive WOM and media resonances, allowing to significantly diversify the arsenal of communication tools with the target audience, as well as to increase the quality and efficiency of promotional messages, which in sum boosts the publicity capital.&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Other varieties of mocap systems (with exception of non-marking one, which works through computer vision) are not used in real time regime for promotional events primarily due to their cumbersome nature. However, they can be employed to create realistic 3D animation for future utilization in promotional campaigns, projects, and actions using augmented reality technologies.&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Key words:&lt;/em&gt;&lt;/strong&gt;&lt;em&gt; motion capture systems (mocap), augmented reality (AR), promotion, empirical marketing.&lt;/em&gt;&lt;/p&gt;

In-vivo three-dimensional motion analysis of the wrist during dart-throwing motion after midcarpal fusion and radioscapholunate fusion.

We recorded the dart-throwing motion and basic motion tasks in patients following radioscapholunate fusion and midcarpal fusion with a three-dimensional motion capture system invivo, using digital infrared cameras to track the movement of reflective skin markers on the hand and forearm. During the dart-throwing motion, 20 healthy volunteers showed a median range of motion of 107°. As expected, patients had significantly reduced wrist range of motion during basic motion tasks and dart-throwing motion compared with the healthy controls, except for ulnar flexion occurring in the dart-throwing motion in patients treated by midcarpal fusion and radial deviation after midcarpal fusion or radioscapholunate fusion. In addition, patients who had undergone radioscapholunate fusion had significantly reduced range of motion during dart-throwing motion compared with patients after midcarpal fusion.

Chilling induces unidirectional solute leak through the locust gut epithelia.

Chill-susceptible insects, like the migratory locust, often die when exposed to low temperatures from an accumulation of tissue damage that is unrelated to freezing (chilling injury). Chilling injury is often associated with a loss of ion balance across the gut epithelia. It has recently been suggested that this imbalance is at least partly caused by a cold-induced disruption of epithelial barrier function. Here, we aimed to test this hypothesis in the migratory locust (Locustamigratoria). First, chill tolerance was quantified by exposing locusts to -2°C and recording chill coma recovery time and survival 24 h post-cold exposure. Longer exposure times significantly increased recovery time and caused injury and death. Ion-selective microelectrodes were also used to test for a loss of ion balance in the cold. We found a significant increase of haemolymph K+ and decrease of haemolymph Na+ concentration over time. Next, barrier failure along the gut was tested by monitoring the movement of an epithelial barrier marker (FITC-dextran) across the gut epithelia during exposure to -2°C. We found a significant increase in haemolymph FITC-dextran concentration over time in the cold when assayed in the mucosal to serosal direction. However, when tested in the serosal to mucosal direction, we saw minimal marker movement across the gut epithelia. This suggests that while cold-induced barrier disruption is present, it is apparently unidirectional. It is important to note that these data reveal only the phenomenon itself. The location of this leak as well as the underlying mechanisms remain unclear and require further investigation.

Jaw kinematics and mandibular morphology in humans

Understanding the influence of feeding behavior on mandibular morphology is necessary for interpreting dietary change in fossil hominins. However, mandibular morphology is also likely to have an effect on feeding behavior, including jaw kinematics. Here we examine the relationships between mandibular morphology and jaw kinematics in humans using landmark-based morphometrics to quantify jaw movement. Three-dimensional movements of reflective markers coupled to the mandible and cranium were used to capture jaw movements while subjects chewed cubes of raw and cooked sweet potato. Geometric morphometric methods were adapted to quantify and analyze gape cycle motion paths. Gape cycles varied significantly across chewing sequences and between raw and cooked sweet potato. Variation in gape cycle size and shape is related to the width (intergonial distance) and length of the mandible. These results underline the fact that jaw kinematic variation within and between taxa is related to and may be influenced by mandibular morphology. Future studies examining kinematic variation should assess the influence of morphological differences on movement.

Determining the ideal mattress firmness based on anthropometric measurements

Introduction: Mattresses need to provide enough support to keep spinal alignment close to a neutral posture, whilst minimising muscle activity and providing optimum pressure relief. There is limited evidence to sug­gest that a 'one size fits all' mattress provides the appropriate support for individuals with diverse body shapes, so a greater understanding of how different mattresses affect the human body is key. By having a more objective approach to choosing a mattress an individual may have an improved quality of sleep. Materials and methods: A ten-camera infrared movement analysis sys­tem recorded the movement of retro-reflective markers placed on the Upper-Mid Thoracic, Mid-Lower Thoracic, Lower Thoracic-Upper Lumbar, Upper-Lower Lumbar and Lower Lumbar-Pelvic areas of the spine. A static image of the spine was taken in a standing position and was used to define each individual's neutral posture. Deviations away from this neutral po­sition were assessed under three different conditions in side lying. Three visually identical mattresses were tested, internally each mattress con­tained a different firmness of spring unit (soft, medium, firm) with an identical gel foam comfort layer. In addition, height, weight, shoulder width and hip circumference measurements were taken to determine differences in body types. Results: Spinal alignment was assessed on 59 healthy participants and no significant differences were seen between the different mattress config­urations. However, further analysis showed significant differences in spi­nal alignment between the different mattress conditions within different body shape subgroups. Subgroups were defined using body weight, height, BMI, shoulder width and hip circumference. Those with a higher body weight had a more neutral spinal alignment when on a firmer mattress, whereas those with a lower body weight were better suited to a softer mattress. Shorter people were better aligned on a softer mattress, and a medium mattress kept the spine in a more neutral position amongst taller people. There were no differentiating factors between shoulder width or BMI groups. However, those with a larger hip circumference had signifi­cantly greater spinal deviations when on a softer mattress. implying that a softer mattress should be avoided by this subgroup. Conclusions: This study suggests that a ·one size fits all' approach to mattresses may not be appropriate. Contrasting body types need different levels of support to improve overall spinal alignment, allowing the inter­vertebral disc to re-hydrate, and spinal muscles to relax throughout the night. The use of simple anthropometric measurements could make the selection of the most appropriate mattress easier for the general public. Acknowledgements: This is part of an Innovate UK Knowledge Transfer Partnership between the University of Central Lancashire and Silentnight Group Ltd.

Analysis of attribute domain for geometrical gesture performed by arm movements

&lt;span&gt;Hand gesture recognition commonly uses a camera to track hand movements and transformed into gesture database by using various computational approaches. Motion tracking utilized to map coordinate point of the subject movement, either in skeletal model or marker tracing. Data from motion trackers usually contains massive coordinate sequences of marker movement. A reliable method is required to select best features and analyze these data. However, the current issue whether the selected features and data presentation are significant for the research or not. This research brings the concept of ontology design for arm gesture recognition systems by utilizing the motion capture system. Ontology is the conceptual structure mainly used to retrieve information by establishing relation in complex data model. The proposed ontology framework is divided into three domains which are knowledge domain, attribute domain and process domain. Knowledge domain holds pre-processed gestural data from motion capture. The attribute domain is that the level where all the attribute elements were presented. This paper shows the analysis of the datasets in attribute domain. The analysis is divided into two parts which is precision measure and ANOVA test. Both analyses are to prove the reliability of datasets in attribute domain. The precision measure is used to remove all the common data for all gesture. A statistical analysis of p-value is lower than 0.01 which means the gestural data are statistically significant to be used for the similarity measure.&lt;/span&gt;

Tracking Marker Movement for Simplicity of Picture Handling

High speed machines and mechanisms are often studied from a sequence of images obtained from high speed videography. The use of markers printed or attached on moving parts can greatly assist in tracking the moving parts. We present the design of a marker suitable for planar motion analysis of mechanism. The marker is designed to make the task of image processing computationally less intensive so as to make real time motion analysis practical. Rosenfeld equivalence table algorithm is used to segment the input image. The new geometry of marker facilitates automatic tracking and provides both position and orientation information. Hu invariant moments are used for recognition of the marker shape in the segmented image. Markers are uniquely identified on the basis of a text code that is placed in a designated location with respect to the marker geometry. In this method, the bounding box for the text code is computed. Knowing the orientation of the marker and therefore the text orientation, it is possible to transform the sub- image, containing the text, so that the text is aligned horizontally. This will permit a standard OCR routine to read the text code. The motion of various moving parts in image sequence can be easily inferred once the position and orientation of each of the marker is known.

Monitoring Intra-Fraction Prostate Motion Using Kv Triggered Imaging during SBRT

To assess the intra-fraction prostate motion in SBRT treatments using kV triggered imaging of implanted fiducial markers. Seven consecutive patients with prostate cancer underwent SBRT at our institution from Dec 2018 to Feb 2019 were studied. All patients received a total dose of 36.25 or 40 Gy in five fractions with two-arc VMAT using 10 MV FFF beams. All patients had three implanted fiducial markers inside the prostate and one patient (#1) had daily rectal balloon insertion. For each patient, a monitoring structure, “fiducial2mm”, was created by expanding 2 mm of the contoured markers. During treatments, KV triggered images were acquired every 60 degrees of gantry rotation. The centers of the markers were auto detected from the triggered images and compared with the fiducial2mm structure. If any marker center was outside of the fiducial2mm contour, treatment was paused automatically and a new CBCT was required to reposition the patient. Four hundred and sixty kV triggered images were exported for this retrospective analysis. The centers of the markers in the triggered images were detected automatically using an in-house image processing program and compared with the expected marker centers from planning CT. The intra-fraction motion of markers was determined by subtracting the measured marker positions in the triggered images from the expected positions, projected to the patient’s lateral, longitudinal and vertical directions. Fiducial markers were detectable in 450 of the 460 triggered images. Of the seven patients, one (#1) required table position adjustment up to 5 mm during treatment in 3 of the 5 fractions. The remaining six patients had no beam interruption or table position correction during treatments. On average, the intra-fraction motion of prostate, measured by fiducial markers was 2.0 mm. The prostate tended to move inferiorly (p<0.001). Intra-fraction motion was not correlated with treatment time. The motion measured from images taken within 5 minutes from CBCT was not statistically different from the images taken after 5 minutes from CBCT. KV triggered imaging is a useful tool to monitor the intra-fraction prostate motion for patients receiving SBRT. The average intra-fraction prostate motion was 2 mm in 3-D vector. With 2 mm intra-fraction margin, most patients do not have treatment interruption when monitored by triggered imaging.Abstract 3748; Table 1Patient# 1 (w rectal balloon)# 2# 3# 4# 5# 6# 7# of triggered images70626368596068Intra fraction motion [mm]w/o table correctionw table correctionNo table correctionLat (left+, right-)0.1 +/- 1.20.0 +/- 0.8-0.1 +/- 1.00.2 +/- 1.0-0.3 +/- 0.8-0.2 +/- 0.90.4 +/- 0.8-0.3 +/- 0.9Long (sup+, inf-)-2.3 +/- 2.8-0.3 +/- 1.4-0.4 +/- 1.20.2 +/- 1.5-0.8 +/- 1.0-0.6 +/- 1.4-0.9 +/- 1.2-1.6 +/- 0.9Vrt (ant-,post+)0.2 +/- 2.30.7 +/- 1.6-1.0 +/- 1.10.3 +/- 1.40.2 +/- 1.10.9 +/- 1.20.7 +/- 0.90.5 +/- 1.13D vector3.7 +/- 2.52.0 +/- 1.32.0 +/- 0.92.1 +/- 1.01.7 +/- 0.91.8 +/- 1.51.9 +/-1.82.1 +/- 1.0 Open table in a new tab

A kinematic study of skilled reaching movement in rat

BackgroundIn the rat, the single-pellet reaching task includes orienting, reaching, grasping and retracting movements. It has previously been described by notation techniques, high-speed video and cineradiographic recordings. Recently, high-definition cameras have been used to track paw and digit movements with DeepLabCut, a machine-learning algorithm for markerless estimation of paw position. New methodOur new approach consists of positioning three high-speed infrared digital cameras to track the full motion of markers on the rat’s body. This provided a previously unavailable 3D recording of skilled reaching kinematics in the rat moving freely in the reaching box, which were analysed by Qualisys Track Manager software and MATLAB. ResultsThis method enabled description of kinematic parameters unobtainable without motion tracking and provided insight into the spatiotemporal metrics of movements used to perform skilled reaching. It revealed that orientation features three steps and reaching has two bimodal start-point distributions, one along the horizontal axis and one along the vertical axis. At the end of reaching, the wrist/paw occupies the same position as the nose at the end of orienting. In grasping, averaging trajectories confirmed the marker lowering and target approaching. Comparison with existing methodsOur method required significantly reduced time to label data and obviates the need for off-line manual marking of videos. It provides an efficient means of capturing volumes containing the entire range of marker movements. ConclusionsThis study validated a new and efficient approach for quantifying rat movement kinematics, useful for comparing preclinical and clinical conditions.