INTRODUCING SITETRACK

Neurosurgery ◽  
2009 ◽  
Vol 64 (suppl_2) ◽  
pp. A110-A122 ◽  
Author(s):  
Kenichi Saito ◽  
Masami Fujii ◽  
Koji Kajiwara ◽  
Michiyasu Suzuki
Keyword(s):  
Regression Analysis ◽  
Stereotactic Radiotherapy ◽  
Head Movement ◽  
Target Localization ◽  
Mean Square ◽  
Localization System ◽  
System Parameters ◽  
Thermoplastic Mask ◽  
Emergency Stop ◽  
The Moment

Abstract OBJECTIVE Immobilization of the head during stereotactic radiotherapy (STR) has, until recently, been fundamental for ensuring accuracy. We developed a continuous motion monitoring system (SiteTrack) to detect and quantify head movement during CyberKnife (Accuray, Inc., Sunnyvale, CA) STR and Leksell (Elekta AB, Stockholm, Sweden) frame fixation. In this study, we present findings obtained during tests of SiteTrack. METHODS SiteTrack is composed of a potentiometer with 4 encoders connected through 4 threads tied to the plastic buttons attached to the thermoplastic mask, in the case of CyberKnife, or by 3 threads directly connected to the Leksell frame. The accuracy of SiteTrack was studied with a phantom using the target localization system of the CyberKnife. During CyberKnife treatment, SiteTrack software sends an emergency stop signal (E-stop) if the patient moves beyond a limit. Seventy-three cases of CyberKnife STR and 7 cases of Leksell frame fixation were monitored. RESULTS In the phantom study, regression analysis showed a significant correlation between SiteTrack and target localization system parameters. The expected root mean square position error at the moment of E-stop was 0.62 ± 0.44 mm when the E-stop limit was set at ±0.5 mm. Twenty-two (30%) of 73 patients kept still during CyberKnife treatment (<0.5 mm); 51 (70%) of 73 patients moved more than 0.5 mm and, thus, caused E-stops. SiteTrack monitoring during frame fixation showed motion beyond ±1 mm in 4 cases and ±0.5 mm in 3 other cases. CONCLUSION Significant head movement can occur during CyberKnife treatment or fixation with a Leksell frame. SiteTrack may improve the accuracy of the CyberKnife as well as frame-based STR.

scholarly journals Exploratory study of electromyographic behavior of the vastus medialis and vastus lateralis at neuromuscular fatigue onset

2014 ◽  
Vol 20 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Cristiano Rocha da Silva ◽  
Danilo de Oliveira Silva ◽  
Deisi Ferrari ◽  
Rúben de Faria Negrão Filho ◽  
Neri Alves ◽  
...  
Keyword(s):  
Exploratory Study ◽  
Vastus Lateralis ◽  
Knee Extension ◽  
Neuromuscular Fatigue ◽  
Isometric Contractions ◽  
Median Frequency ◽  
Vastus Medialis ◽  
Mean Square ◽  
Electromyographic Signal ◽  
The Moment

This study aimed to determine and analyze the neuromuscular fatigue onset by median frequency (MDF) and the root mean square (RMS) behavior of an electromyographic signal (EMG). Eighteen healthy men with no prior knee problems initially performed three maximum voluntary isometric contractions (MVIC). After two days of MVIC test, participants performed a fatiguing protocol in which they performed submaximal knee-extension contractions at 20% and 70% MVIC held to exhaustion. The MDF and RMS values from the EMG signals were recorded from the vastus medialis (VM) and the vastus lateralis (VL). Analysis of the MDF and RMS behavior enabled identification of neuromuscular fatigue onset for VM and VL muscles in 20% and 70% loads. Alterations between the VM and VL in the neuromuscular fatigue onset, at 20% and 70% MVIC, were not significant. These findings suggest that the methodology proposal was capable of indicating minute differences sensible to alterations in the EMG signals, allowing identification of the moment when the MDF and the RMS showed significant changes in behavior. The methodology used was also a viable one for describing and identifying the neuromuscular fatigue onset by means of the analysis of EMG signals.

Estimation of Gait Independence Using a Tri-Axial Accelerometer in Stroke Patients

2018 ◽  
Vol 26 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Yoshifumi Kijima ◽  
Ryoji Kiyama ◽  
Masaki Sekine ◽  
Toshiyo Tamura ◽  
Toshiro Fujimoto ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Gait Analysis ◽  
Root Mean Square ◽  
Wireless Sensors ◽  
Gait Velocity ◽  
Mean Square ◽  
Key Factors ◽  
Stroke Patients ◽  
Gait Quality ◽  
Healthy Control

The purpose of this study was to clarify whether a gait analysis using an accelerometer could estimate gait independence. Eighty-six stroke patients and 21 healthy control subjects participated in this study. Stroke patients were identified as dependent or independent based on their gait ability. The acceleration of the trunk and bilateral thigh was measured using three wireless sensors during walking. The root mean square, gait regularity, and symmetry were calculated from the acceleration to estimate gait quality. ANCOVA showed that gait regularity of the trunk and bilateral thigh were significantly lowest in the dependent group, regardless of gait velocity. A logistic regression analysis showed that the regularity and root mean square of the anteroposterior acceleration of the unaffected thigh were the key factors for estimating gait independence. This study suggests that an acceleration-based gait analysis facilities gait independence estimation, and is a useful tool during the rehabilitation of stroke patients.

Detailed Analyses of the Tow Line Behaviour in Single, Double and Triple Towages in Case of Emergency Stop and Catenary

2011 ◽  
Author(s):  
A. J. Bos ◽  
R. Heemskerk
Keyword(s):  
Element Model ◽  
Numerical Approach ◽  
Stopping Distance ◽  
Contingency Plans ◽  
Safe Side ◽  
Emergency Stop ◽  
The Wire ◽  
Engine Failure ◽  
The Moment ◽  
Model Approach

Two phenomena have been studied in order to enhance the contingency plans and improve the safety of towages. 1. For multi tug towages it is important to prepare proper contingency plans for the case that a tug fails and overrun by the tow is a probability, especially the towages of FPSO’s and huge rigs performed by more tugs. A model has been developed to assess the time between the failure and the moment the tow will collide. After thorough research not the stopping distance proved important, but the time it takes for both objects to collide. In case the tug is allowed to be pulled towards the FPSO, the time from engine failure to collision is 380 [s] or 6 minutes 20 seconds. Both objects will collide with a speed difference of 2.28 [m/s]. In case the towline is cut, the time until collision is 1479 [s], or 24 minutes and 40 seconds. In this case it is very important to cut the towline instantly after the engine failure. Otherwise the tug will gain a negative speed of 1 m/s within 2 minutes, and the distance between the FPSO and the tug will be reduced to 683 [m] already. 2. Grounding of tow lines must be avoided the standard of the catenary approach to assume a hyperbolic shape is investigated and a detailed finite element model approach shows that the standard assumptions are not accurate enough. A numerical approach has been used to calculate the effect of current and loss of tension in the wire. The influence of current along the towing-wire depends on the speed, diameter, length and the angle of the towing-wire in the water. The maximum depth increases when the speed increases or the tension in the wire decreases. In the example the depths are on the safe side for depths below 35[m], but above 35[m] the values are too optimistic when current is involved.

scholarly journals Nonlinear Regression Based Health Monitoring of Hysteretic Structures under Seismic Excitation

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
C. Xu ◽  
J. Geoffrey Chase ◽  
Geoffrey W. Rodgers
Keyword(s):  
Regression Analysis ◽  
Nonlinear System ◽  
Nonlinear Regression ◽  
Health Monitoring ◽  
Linear Regression Analysis ◽  
Hysteresis Loops ◽  
Nonlinear Regression Analysis ◽  
Monitoring Method ◽  
System Parameters ◽  
Damage Indicators

This paper presents a health monitoring method using measured hysteretic responses. Acceleration and infrequently measured displacement are integrated using a multirate Kalman filtering method to generate restoring force-displacement hysteresis loops. A linear/nonlinear regression analysis based two-step method is proposed to identify nonlinear system parameters. First, hysteresis loops are divided into loading/unloading half cycles. Multiple linear regression analysis is applied to separate linear and nonlinear half cycles. Preyielding stiffness and viscous damping coefficient are obtained in this step and used as known parameters in the second step. Then, nonlinear regression analysis is applied to identified nonlinear half cycles to yield nonlinear system parameters and two damage indicators: cumulative plastic deformation and residual deformation. These values are closely related to structural status and repair costs. The feasibility of the method is demonstrated using a simulated shear-type structure with different levels of added measurement noise and a suite of ground motions. The results show that the proposed SHM method effectively and accurately identifies physical system parameters with up to 10% RMS added noise. The resulting damage indicators can robustly and clearly indicate structural condition over different earthquake events.

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