Amplitude Of Motion Research Articles

Post-traumatic patellar tendon ossification in children: a case series

Background. Fractures of the bones that form the knee joint in children are quite rare, accounting for up to 6% of all bone fractures. These include avulsion fractures of the patellar apex as well as tibial tuberosity avulsion fractures, which may result in patellar tendon ossification. Based on literature, the ossification may also occur in cases of primary or chronic (complete or partial) patellar tendon tears. Such a complication is quite rare in pediatric traumatology; it requires differential diagnosis and various surgical tactics. The aim of the study is to present a clinical and radiological picture of post-traumatic patellar tendon ossification in children and its surgical treatment outcomes using a case series as an example. Methods. We present a monocenter retrospective series of 4 male patients. Anamnestic, clinical, radiological and histological data were analyzed. Results. The patients’ mean age was 14 (range, 11-16) years. In all cases, there was a history of trauma. Initially, after getting injured, the patients were treated for a knee injury. In one patient, as a result of his falling on 2 limbs, a bilateral pathology was observed; in other three cases, the pathology was unilateral. Flexion contracture and pain syndrome prevailed in the clinical picture. All patients underwent surgery ranging from excision of ossifications to excision of ossifications with reconstruction of tendon defects and refixation of the tibial tuberosity with osteosynthesis. In all cases, knee joint contracture was eliminated and the volume of movement was fully restored. Histology showed fragments of mature bone tissue represented by thinned bone beams with focal osteoclastic reaction and areas of endochondral ossification. Conclusions. The clinical picture of pediatric patients with patellar tendon ossification manifests in the form of a chronic cascade of symptoms and functional and topographic disorders: patellar tendon ossification, patella alta, anterior knee pain, flexion contracture and rectus femoris muscle hypotrophy. X-ray and MRI data determine a formation of bone density with uneven clear contours in the projection of the patellar tendon, along with patella alta and the Caton-Deschamps index increasing more than 1.3. The primary treatment method of the developed complication is the surgical one, which leads to the restoration of the full amplitude of movements in the knee joint.

Functional, instrumental test of flexion-extension movements of the wrist joint. Normative parameters.

Background: Stroke is a significant medical and social issue due to its high incidence and mortality rates, with a trend toward increasing overall cases. In 80% of patients, upper limb dysfunction persists. Existing methods, such as clinical scales and questionnaires, are criticized for their subjectivity and lack of precision. There is a need to develop an instrumental method for assessing upper limb function that can be applied in clinical settings. Aims: To develop a functional test for the objective diagnosis of wrist joint function applicable in clinical settings. Methods: A functional test was proposed to assess the biomechanics of the wrist joint using inertial sensors. The study involved 15 healthy volunteers (5 men and 10 women, aged 23 to 33), with no joint diseases or neurological disorders. The study was conducted over one year (2022–2023). The primary endpoint was to determine the amplitude, time, and trajectory of wrist joint movements during two tests—"Wrist-0" and "Wrist-Flex." Evaluation was based on the duration of the movement cycle, maximum amplitude, and movement phase. Results: Assessment of upper limb function using clinical scales (ARAT, FMA-UE, MRC) showed that parameters were consistent with those of healthy individuals. In the "Wrist-0" test, movement amplitude was significantly lower compared to the "Wrist-Flex" test (p0.05). There were no statistically significant differences in movement amplitude between the right and left limbs in either test (p0.05). The phase of maximum flexion in the "Wrist-0" test occurred significantly earlier than in the "Wrist-Flex" test for the right hand (p0.05). The movement cycle duration did not differ significantly between tests for the right hand (p0.05) but was significantly longer in the "Wrist-Flex" test for the left hand (p0.05). Conclusions: Normative parameters for the functional test have been established. Minor differences in function between the right and left wrist joints were observed. The proposed test requires minimal time to administer and can be used for the objective diagnosis of wrist joint function in patients.

A Method for Classification of Chest Motion base on Time-domain Signals of IR-UWB Radar

Abstract As an instrument for wireless sensing and measurement, radar is widely used in target tracking and localization. And Impulse Radio Ultra-Wideband (IR-UWB) radar, with its excellent characteristics of high resolution and large bandwidth, has become a research hotspot in the fields of perception and ranging, smart home and so on. However, when radar sampling rates are low, It's hard to recognize human activity only based on radar images. Also when the amplitude of human movement is too tiny, it is difficult to recognize the human activitise just by the energy amplitude of the echo. This paper proposes a novel method to classify small amplitude human chest motions by time-domain signal from Impulse Radio Ultra-Wideband (IR-UWB) radar with a low sampling rate. Based on the energy and phase of the radar echoes, our method can detect the onset of human's motion and differentiate between normal breathing and apnea. Additionally, the amplitude of human's motion can be distinguished based on the distance range spanned by the echoes. Finally, a two-step classification method is employed to distinguish between yawning and coughing in small motions. The paper reports a classification precision of 0.9186, recall rate of 0.9163, and F1 score of 0.9172 for the proposed method under experimental conditions. The experimental performance outperformed the adopted comparison method based on MobileNetV3. We also tested the performance of the proposed method under different angle and distance conditions, which demonstrates the feasibility of our method.

Studies on the free vibrations of tether of submerged floating tunnel involving tube motion by using different mechanical models

To accurately acquire the frequency/mode of the tethers of the tether-type submerged floating tunnel (SFT), which is an innovative underwater traffic structure with great potential, the dynamic frequency (DF) and wet mode (WM) of the tether involving the tube motion are studied. The novelty lies on the proposed novel method where the analytical relation of the tether’s DF and WM with the moving boundaries and the structural parameters is directly built. The gap that the unreported premise of quasi-static treatment for the global vibratory SFT and the unmentioned principle of the top tension of the tether equaling the net buoyancy within its supporting range is filled. Firstly, four mechanical models named M1∼M4 are respectively established by equating the tether as a beam or string with moving boundaries, taking into accounts the bending stiffness, wet-weight and other geometrical/material factors. Secondly, the relationships between the band-width, upper/lower limits of the DF and the inclination angle, vertical height, buoyancy-weight-ratio (BWR), motion amplitude are founded. Thirdly, the distribution laws of the DF during the vertical periodic motion of tube, as well as the parameter sensitivity range of the WM to the span-wise effect of wet-weight and the vertical height, are studied. The results show that the tether exhibits DF under the tube motion. The band-width of DF is sensitive to the BWR, inclination angle, vertical height and motion amplitude, and its upper/lower limits exhibit varying degrees of variation patterns with the changing of these parameters. The wet-weight and the vertical height are two main influencing factors of the WM. The proposed method provides a new treatment idea for further in-depth research on the locking zone of the vortex-induced vibration (VIV) and parametric vibration for the tether of SFT.

Sloshing-induced evolution of self-cleaning performance and flow characteristics within a tank installed on an offshore aquaculture vessel

In this study, a six-degree-of-freedom (6-DOF) motion platform is utilized to simulate the transverse rolling motion of aquaculture tanks aboard deep-sea aquaculture vessels. It examines the effects of different inlet configurations (single and four-pipe inlet), rolling motions (amplitude Θ and period T), and inlet pipe jet angles α (the acute angle between the jet direction of the inlet pipe and the inclined wall to which it is connected) on the self-cleaning capabilities and flow field characteristics of the aquaculture tank. The findings indicate that the waste collection time in the tank is affected by the combined influences of rolling amplitude and period. In the single-pipe inlet configuration, waste collection time increases with the rolling period and initially increases, then decreases with the rolling amplitude. In the four-pipe inlet configuration, waste collection time increases with the rolling period and decreases with the rolling amplitude. Optimal waste collection performance is achieved at α = 45° in both configurations. Regarding flow field characteristics, variations in rolling period and amplitude significantly alter the flow field within the aquaculture tank. In both configurations, as the period decreases and the amplitude increases, the high-velocity regions and the central vortex area within the tank expand, and the average flow velocity of the water also rises. This corresponds to a reduction in waste collection time and an increase in the waste collection rate. In both configurations, the Flow field is most uniform at α = 45°, which corresponds to the highest waste collection capabilities among all jet angles. The results indicate that while decreasing the rolling period and increasing the amplitude can enhance the self-cleaning capabilities, they also lead to excessively rapid water flow velocities. In practical applications, it is important to select appropriate farming areas based on fish suitability and to choose the correct inlet jet angles for different numbers of inlets. The findings can provide theoretical support and a scientific basis for optimizing the flow characteristics and self-cleaning performance of aquaculture vessels under rolling motion and contribute positively to the advancement of deep-sea aquaculture technology.

Low-side and multi-tone suppression in the base of the gerbil cochlea

The cochlea’s mechanical response to sound stimulation is nonlinear, likely due to saturation of the mechano-electric transduction current that is part of an electromechanical feedback loop. The ability of a second tone or tones to reduce the response to a probe tone is one manifestation of nonlinearity, termed suppression. Using optical coherence tomography to measure motion within the organ of Corti, regional motion variations have been observed. Here, we report on the suppression that occurs within the organ of Corti when a high sound level, low frequency suppressor tone was delivered along with a sweep of discreet single-tones. Responses were measured in the base of the gerbil cochlea at two best frequency locations, with two different directions of observation relative to the sensory tissue’s anatomical axes. Suppression extended over a wide frequency range in the outer hair cell region, whereas it was typically limited to the best frequency peak in the reticular lamina region and at the basilar membrane. Aspects of the observed suppression were consistent with the effect of a saturating nonlinearity. Recent measurements have noted the three-dimensional nature of organ of Corti motion. The effects of suppression observed here could be due to a combination of reduced motion amplitude and altered vibration axis.

Towards Less Invasive Instruments For Cardiac Tissue Stabilizing

Abstract Beating-heart surgery is performed to reduce patient trauma but depending on the intervention requires tissue stabilization through vacuum cardiac tissue stabilizers. Current designs either require open chest sternotomy or display significant residual motion when used minimally invasively. Active motion compensation methods require complex control algorithms and expensive technology. We propose a novel design for a vacuum tissue stabilizer with expandable suction feet enabling a larger stabilized area and increased motion reduction. Its performance is evaluated on a heart phantom using a silicon membrane mimicking cardiac tissue properties. The motion of the membrane is captured using a stereo camera and marker points on the membrane surface. The results are then compared to a state-of-the-art tissue stabilizer. The extended stabilizer is found to stabilize a 110% larger area while achieving similar motion amplitude reduction. Thus, extendable stabilizers seem to be a promising solution for improved cardiac tissue stabilization in less invasive beating-heart surgery.

Developing a multi-region coupled analysis method for floating offshore wind turbine based on OpenFOAM

As floating offshore wind turbines (FOWTs) continue to scale up in size, the simulation technology for coupling aerodynamic, hydrodynamic, and mooring forces presents significant challenges. This study proposes a multi-region coupled simulation solver, MRFoam, for FOWTs. The multi-region coupled method divides the computational domain into two parts: the turbine region and the floating platform region. This division reduces the number of grid cells and facilitates modular simulations for various structural forms and operating conditions. Compared to the traditional fully coupled method, the multi-region coupled method significantly improves computational efficiency. For various models and grid quantities, the computational efficiency of the multi-region coupled method is nearly double that of the fully coupled method with the results remaining almost identical. Subsequently, the multi-region coupled model is applied for the aerodynamic, hydrodynamic and mooring dynamic analyses of a large-scale FOWT (IEA 15 MW) under various wind and wave conditions. The study found that a decrease in wind speed increases the amplitude of surge response while decreasing the amplitude of heave response. Additionally, at lower wind speeds, an increase in wave height amplifies the platform's motion response, while the variation in aerodynamic thrust is slightly influenced by the change in the platform's motion amplitude.

EHFusion: an efficient heterogeneous fusion model for group-based 3D human pose estimation

AbstractStimulated by its important applications in animation, gaming, virtual reality, augmented reality, and healthcare, 3D human pose estimation has received considerable attention in recent years. To improve the accuracy of 3D human pose estimation, most approaches have converted this challenging task into a local pose estimation problem by dividing the body joints of the human body into different groups based on the human body topology. The body joint features of different groups are then fused to predict the overall pose of the whole body, which requires a joint feature fusion scheme. Nevertheless, the joint feature fusion schemes adopted in existing methods involve the learning of extensive parameters and hence are computationally very expensive. This paper reports a new topology-based grouped method ‘EHFusion’ for 3D human pose estimation, which involves a heterogeneous feature fusion (HFF) module that integrates grouped pose features. The HFF module reduces the computational complexity of the model while achieving promising accuracy. Moreover, we introduce motion amplitude information and a camera intrinsic embedding module to provide better global information and 2D-to-3D conversion knowledge, thereby improving the overall robustness and accuracy of the method. In contrast to previous methods, the proposed new network can be trained end-to-end in one single stage. Experimental results not only demonstrate the advantageous trade-offs between estimation accuracy and computational complexity achieved by our method but also showcase the competitive performance in comparison with various existing state-of-the-art methods (e.g., transformer-based) when evaluated on two public datasets, Human3.6M and HumanEva. The data and code are available at doi:10.5281/zenodo.11113132

Nonlinear Dynamic Stability Analysis of Ground Effect Vehicles in Waves Using Poincaré–Lindstedt Perturbation Method

In this study, we present an analytical tool that can be used to predict the nonlinear dynamic response of ground effect vehicles (GEVs) advancing through sinusoidal head-sea waves. GEVs exhibit a unique instability phenomenon known as porpoising, which is an oscillatory motion along the heave and pitch axes that can cause serious structural damage. The heaving and pitching equations of motion are presented in the form of coupled, forced, and nonlinear Duffing-type equations with cubic nonlinearity. The analytical model developed in this study leverages the Poincaré–Lindstedt perturbation method to express the amplitude and frequency of motion in terms of all physical parameters. The accuracy and reliability of the proposed model were validated through computational fluid dynamics (CFD) simulations based on incompressible unsteady Reynolds-averaged Navier–Stokes (RANS) equations. The results show a strong agreement between the analytical tool and the CFD simulations, with minor discrepancies due to assumptions inherent in the simulations, particularly the assumption that seawater only passes beneath the hull, resulting in increased buoyancy forces and reduced damping. This study offers a novel and practical method for predicting the dynamic stability of GEVs under realistic sea conditions, potentially enhancing safety and operational efficiency by mitigating the risks associated with porpoising.

Non-linear dynamic behavior of T0 and T90 mesopelagic trawls based on the Hilbert–Huang transform

Although adopting the T90 mesh orientation on the trawl net can improve the selectivity of the trawl codend, it is unknown whether the T90 mesh orientation influences the dynamic behavior of the trawl system. Therefore, this study uses non-linear dynamic analysis to examine the effect of mesh orientations, mesh size, and twine diameter on the mesopelagic trawls' fluttering motions and hydrodynamic force responses. Three trawls are designed with different mesh orientations (T0 and T90), mesh sizes (40 mm and 60 mm), and twine diameters (0.96 mm and 1.11 mm) on the codend and codend extension sections of the trawl model based on Tauti's law. These trawls are tested in a flume tank under various flow velocities and catch sizes. A time-frequency analysis method based on the Hilbert–Huang transform is utilized to analyze each trawl's dynamic responses, including motions and drag force responses. The results are compared with those obtained through Fourier analysis using power spectral density. The results highlight that the oscillation amplitude of the surge motion of the T90 trawl is higher than that of the T0 trawl. In contrast, the T90 trawl's heave motion oscillation amplitude is smaller. The dominant frequency of the periodic high-energy coherent structures of the surge and heave motions are detected at a low frequency. The surge and heave motions of the T0 trawl have a greater response to the current components with lower frequencies than that of the T90 trawl. An increase in mesh size, a decrease in twine diameter, and a change in mesh orientation decrease the drag force. The inherent characteristic oscillations of the drag force response for the three trawl models are synchronized with the low-frequency characteristic of surge and heave motions. The gravity periods of the low-frequency mode components of drag force, surge motion, and heave motion for the T90 trawl are higher than those for the T0 trawls. In other words, the T90 trawl is more stable and selective than the T0 trawl. The findings of this study offer important information for comprehending and enhancing the selectivity of trawls in marine mesopelagic fisheries, particularly for exposing the effects of mesh orientation and design parameters on trawl performances.

Toward an Operational Dynamical Model of Lateral Manual Interception Behavior.

We develop a dynamics-based model of discrete movement for lateral manual interception capable of generating movements with realistic kinematics. For the present purposes, we focus on the situation of to-be-intercepted targets moving at constant speed along rectilinear trajectories oriented orthogonally with respect to the interception axis. The proposed phenomenological model is designed to capture the time evolution of empirically observed hand movements along the interception axis under different conditions of target arrival location and target speed-induced time pressure. Pattern formation dynamics combine a Duffing stiffness function, allowing for creating a fixed-point attractor at the perceived location of the target arrival on the interception axis, with a hybrid Rayleigh plus Van der Pol damping function. After parametrizing the model for required movement direction (left/right), amplitude, and duration, it adequately reproduces the (variations in) empirically observed kinematics with a single set of four coefficients for all conditions considered. The model is also demonstrated to inherently incorporate speed-accuracy trade-off characteristics.

The lateral habenula regulates stress-related respiratory responses via the monoaminergic system.

Psychologic stress induces behavioral and autonomic responses such as acceleration of respiration. The lateral habenula (LHb) is noted to be involved in stress-induced behavioral responses. However, its involvement in stress-induced respiratory responses is unknown. In this study, we aimed to analyze whether and how the LHb regulates respiration. Electrical stimulation of the LHb of anesthetized Wistar male rats increased respiratory frequency and minute ventilation, calculated by respiratory frequency × thoracic movement amplitude. Systemic administration of a dopaminergic receptor antagonist, clozapine, suppressed the LHb-induced respiratory responses. On the other hand, administration of a serotonergic receptor antagonist, methysergide, significantly accelerated the LHb-induced increase in respiratory frequency, together with suppressing the thoracic movement amplitude. To clarify the source of dopaminergic modulation, we inhibited the ventral tegmental area (VTA), which contains dopaminergic neurons and receives inputs from the LHb, by administering microinjections of a GABAA agonist, muscimol. The bilateral inhibition of the VTA almost abolished the LHb-induced respiratory responses. These results suggest that LHb activation causes respiration acceleration, mainly mediated by dopaminergic neurons in the VTA and suppressively modulated by the serotonergic system. Neural circuits originating in the LHb may be a key modulator for respiration during psychological stress.

The interaction of syntax, non-manuals, and prosodic cues as potential topic markers in Austrian Sign Language

Abstract Topic is often marked only by prosody across languages. In sign languages, prosody is expressed by features similar to those in speech: i.e., sign duration, velocity and amplitude of movement (cf. slope and range of pitch). Topicalized signs usually occur sentence-initially, are followed by a pause, and may show longer duration than nontopics. We used pausing and duration characteristics to resolve a puzzle concerning the status of OSV sentences in Austrian Sign Language (ÖGS): are they a nonmanually unmarked variant of non-manually marked topic sentences (O,SV), or are they a within-clause variant of the basic SOV order serving an as-yet-unknown discourse function? We investigated the temporal parameters of prosodic cues of 160 sentences produced by a fluent ÖGS signer: 40 in each of four conditions — SOV, OSV, S,OV, and O,SV. Overt topic marking effects on signing dynamics consisted of (1) lengthening of the sentence-initial topic phrases, causing a delay of the onset of the argument following the topic-marked item, and (2) a shortened duration of the noun phrase following the topic-marked item. Critically, the initial argument of OSV sentences did not show these prosodic cues, indicating that the initial argument O is not treated as being the same kind of topic as in the non-manually marked O,SV sentences. In accordance with the previous literature on pausing and lack thereof, we suggest that OSV might be akin to spoken German scrambling (within-clause movement), although the function performed remains to be investigated. The findings characterize parameters of temporal structure in the physical markers of topic in ÖGS and point to cross-linguistic variability in prosodic marking for topicalized structures.

Imaging lung tumor motion using integrated-mode proton radiography-A phantom study towards tumor tracking in proton radiotherapy.

Motion of lung tumors during radiotherapy leads to decreased accuracy of the delivered dose distribution. This is especially true for proton radiotherapy due to the finite range of the proton beam. Methods for mitigating motion rely on knowing the position of the tumor during treatment. Proton radiography uses the treatment beam, at an energy high enough to traverse the patient, to produce a radiograph. This work shows the first results of using an integrated-mode proton radiography system to track the position of moving objects in an experimental phantom study; demonstrating the potential of using this method for measuring tumor motion. Proton radiographs of an anthropomorphic lung phantom, with a motor-driven tumor insert, were acquired approximately every 1s, using tumor inserts of 10, 20, and 30mm undergoing a known periodic motion. The proton radiography system used a monolithic scintillator block and digital cameras to capture the residual range of each pencil beam passing through the phantom. These ranges were then used to produce a water equivalent thickness map of the phantom. The centroid of the tumor insert in the radiographs was used to determine its position. This measured position was then compared to the known motion of the phantom to determine theaccuracy. Submillimeter accuracy on the measurement of the tumor insert was achieved when using a 30mm tumor insert with a period of 24s and was found to be improved for decreasing motion amplitudes with a mean absolute error (MAE) of 1.0, 0.9, and 0.7mm for 20, 15, and 10mm respectively. Using smaller tumor inserts reduced the accuracy with a MAE of 1.8 and 1.9mm for a 20 and 10mm insert respectively undergoing a periodic motion with an amplitude of 20mm and a period of 24s. Using a shorter period resulted in significant motion artifacts reducing the accuracy to a MAE of 2.2mm for a 12s period and 3.1mm for a 6s period for the 30mm insert with an amplitude of20mm. This work demonstrates that the position of a lung tumor insert in a realistic anthropomorphic phantom can be measured with high accuracy using proton radiographs. Results show that the accuracy of the position measurement is the highest for slower tumor motions due to a reduction in motion artifacts. This indicates that the primary obstacle to accurate measurement is the speed of the radiograph acquisition. Although the slower tumor motions used in this study are not clinically realistic, this work demonstrates the potential for using proton radiography for measuring tumor motion with an increased scanning speed that results in a decreased acquisitiontime.

Experimental and Numerical Study in Dynamic Compaction of Weakly-Cohesive Soils

The rheological modeling of soil–drum interaction in the vibratory compaction process is a complex process. This paper aims to describe the behavior of soil–drum interaction through lumped parameter modeling. The amplitude of the vertical motion is evaluated for dynamic conditions using the rheological models (generalized and advanced Kelvin–Voigt-based models) and compared with the experimental results obtained from weakly cohesive soil compaction. Different modeling approaches are considered, and the results reveal that the properties of the soil as input play a vital role in the accuracy of the modeling.

Experimental and numerical investigations on responses of ship rolling motion coupled with liquid sloshing inside three tanks with and without baffles

Rolling response of a floating production storage and offloading coupled with sloshing inside three liquid tanks with and without baffles under different wave periods is analyzed experimentally in a towing tank. The main focuses of this study are to examine the effect of baffles on natural period and amplitude of ship rolling motion coupled sloshing for various tank filling depths. The experimental results show that baffles decrease the natural period of ship rolling motion for low filling conditions (20% and 30%). However, when the filling depths are high (e.g., 60% and 70%), the natural period is increased due to the installation of the baffles. The changing of natural period is revealed quantitatively by the change of the sloshing-induced added mass calculated by the numerical potential flow model. The amplitude of ship rolling motion coupled with sloshing without baffles reveals two typical phenomena, namely the anti-rolling effect at low filling conditions and the enhanced-rolling effect at high filling conditions, depending on the dominant factor between the hydrostatic and the hydrodynamic forces. Baffles are effective in suppressing the amplitude of ship rolling motion, especially at its natural period. Their effect is more obvious for low filling condition than that for high filling conditions. This is because baffles are more effective in stopping the fluid inside the tanks from flowing to the inclined side when the filling depth is low. It is also found that baffles can decrease the sloshing-induced mass at low filling conditions and increase that at middle and high filling conditions. The above-mentioned changes are the reasons for the decrease and increase in the natural period of ship rolling motion at low and high filling conditions, respectively, due to the application of baffles.

The analysis of traveling wave solutions and dynamical behavior for the stochastic coupled Maccari's system via Brownian motion

The stochastic coupled Maccari's system (MS) is a kind of important nonlinear partial differential equations to describe fluid flow, plasma physics, nonlinear optics and so on. In this article, the dynamical behavior and some new exact traveling wave solutions of the system are investigated. By means of complex traveling wave transformation, the system is transformed into a nonlinear ordinary differential equation. The dynamical behavior of the system as well as its perturbation case are illustrated by bifurcation theory. And then, some new stochastic traveling wave solutions of the system are extracted based on the theory of polynomial complete discrimination system. To show the effect of stochastic factor on the solutions, their structures under different Brownian motion amplitudes are compared by several sets of graphs. The results obtained in this paper have supplemented the study of the system, and the technique used to exploit the traveling wave solutions are effective.

Wood Chippers

The position and shape of the feed channel (FC) in low-power woodchippers significantly affect the way machine operators' upper limbs move. The execution of operator's movements can be accomplished in different working areas: comfortable, acceptable, or not recommended due to overloads in the musculoskeletal system. Three groups of male subjects from Central Europe, divided according to anthropometric dimensions from centile groups C5, C50 and C95, were selected to assess upper limb movement, by adopting a Motion Capture measurement method. The tests have shown that the limb closer to the FC (left hand in this study) carries out all the movements in the allowed zone (AZ), while between 79% and 96% of the limb movement is contained within the comfort zone (CZ). The right limb has a greater amplitude of motion outside the CZ working area – from 0% to 69% and for AZ – in the CZ can vary by up to 51%. It was found that commercial low-power woodchippers deployed in urban areas, typically induce overloads in the musculoskeletal system of the operator during the use. Based on the research results, the authors see the need to improve FC position adjustment for the operators of these machines.

Effect of breathing phase number on the 4D robust optimization for pancreatic cancer intensity modulated proton therapy

PurposeRespiratory movement, as one of the main challenges in proton therapy for pancreatic cancer patients, could not only lead to harm to normal tissues but also lead to failure of the tumor control, resulting in irreversible consequences. Including respiratory movements into the plan optimization, i.e. 4D robust optimization, may mitigate the interplay effect. However, 4D robust optimization considering images of all breathing phases is time-consuming and less efficient. This work aims to investigate the effect of the breathing phase number on the 4D robust optimization for pancreatic cancer intensity modulated proton therapy (IMPT) by examining plan quality and computational efficiency.MethodsA total of 15 pancreatic cancer patients were retrospectively analyzed. In this study, both anterior-fields and posterior-fields plans were created for each patient. For each plan, six four-dimensional (4D) robust treatment planning strategies with different numbers of respiratory phases and one three-dimensional (3D) treatment plan were created. Optimization of the plans were performed on all ten phases (10phase plan), two extreme phases (2phase plan), two extreme phases plus an intermediate state (3phase plan), two extreme phases plus the 3D CT (3Aphase plan), six phases during the exhalation stage (6Exphase plan), six phases during the inhalation stage (6Inphase plan) and 3D Computed Tomography (CT) scan image (3D plan), respectively. 4D dynamic dose (4DDD) was then calculated to access the interplay effect by considering respiratory motion and dynamic beam delivery. Plan quality and dosimetric parameters for the target and organs at risk (OARs) were then analyzed.ResultsCompared to the 4D plans, 3D plan performed terribly in terms of target coverage and organs at risk. Target dose in anterior-fields plan varied slightly among all six 4D treatment planning strategies. Both the 6Exphase and 6Inphase plans demonstrated performance that was comparable to the 10phase plan in target coverage, outperforming the other five plans for anterior-fields plan. It’s basically the same for the posterior-fields plan. The six strategies showed similar OARs sparing effect for both anterior-fields and posterior-fields plan. Compared with the 10phase plan, the average decline rates of the optimization time of the six plans of 2phase, 3phase, 3Aphase, 6Exphase, 6Inphase, and 3D were 73.26 ± 6.54% vs. 74.48 ± 6.63%, 65.80 ± 7.89% vs. 65.81 ± 9.58%, 54.67 ± 11.52% vs. 65.75 ± 9.58%, 42.14 ± 13.57% vs. 39.63 ± 16.93%, 37.72 ± 11.70% vs. 40.79 ± 13.62% and 75.52 ± 8.21% vs. 80.67 ± 5.62%, respectively (anterior vs. posterior). With the decrease of the number of phases selected for optimization, the decline rates increased, while the other dosimetry parameters generally showed a deterioration trend.ConclusionIn this study, a comprehensive evaluation of six 4D robust treatment planning strategies and one 3D treatment planning strategy for pancreatic cancer patients receiving IMPT was performed. The results showed that six 4D robust optimization strategies were comparable in common posterior field therapy. 2phase and 3phase (including 3Aphase) treatment planning strategies could replace the 10phase treatment planning strategy. It should be noted that patients with large motion amplitudes should receive special attention. The dosimetric performance of the 6Exphase and 6Inphase plans closely aligned with that of the 10phase plan in anterior fields. These plans offered a feasible alternative to 10phase treatment planning strategy by reducing optimization time while maintaining dose coverage of the target and protection of OARs. This research provides guidelines to reduce optimization time and improve clinical efficiency for pancreatic cancer IMPT.