4D System Research Articles

A new 5D hyperchaotic system based on modified generalized Lorenz system

This paper reports a new five-dimensional (5D) hyperchaotic system with three positive Lyapunov exponents, which is generated by adding a linear controller to the second equation of a 4D system that is obtained by coupling of a 1D linear system and a 3D modified generalized Lorenz system. This hyperchaotic system has very simple algebraic structure but can exhibit complex dynamical behaviors. Of particular interest are the observations that the hyperchaotic system has a hyperchaotic attractor with three positive Lyapunov exponents under a unique equilibrium, three or infinite equilibria, and there are three types of coexisting attractors of this new 5D hyperchaotic system. Numerical analysis of phase trajectories, Lyapunov exponents, bifurcation, Poincare projections and power spectrum verifies the existence of the hyperchaotic and chaotic attractors. Moreover, stability of hyperbolic or non-hyperbolic equilibria and two complete mathematical characterization for 5D Hopf bifurcation are rigorously studied. Finally, some electronic circuits are designed to implement the 5D hyperchaotic system.

Can different occlusal positions instantaneously impact spine and body posture? : A pilot study using rasterstereography for a three-dimensional evaluation.

Orthodontists influence dental occlusion directly. To suggest any link between dental occlusion and body posture is highly contentious, as evidenced by the literature. Rasterstereography, an optical technique that enables three-dimensional (3D) body measurements to be collected, has not yet been used to impartially examine whether different occlusal positions could instantaneously alter spine and body posture. We therefore set out to use this technique to nonsubjectively evaluate this question under static conditions. Optical body scans were collected for 44 subjects, using the Diers formetric 4D system, for seven different mandible positions. In total, ten spinal and body posture parameters were assessed (trunk inclination, trunk imbalance, pelvic tilt, pelvic torsion, fleche cervicale, fleche lombaire, kyphotic angle, lordotic angle, surface rotation, and lateral deviation) for each mandible position and compared with scans performed with habitual intercuspation (HIC). Significant body posture deviations were found for the fleche cervicale (positionof the mandible: right eccentrically), fleche lombaire (positionsof the mandible: physiologic rest position, cotton rolls on both sides, bite elevation 1mm), and the kyphotic angle (positionsof the mandible: cotton rolls on both sides, right eccentrically). No other significant differences were detected. Data for the parameters that varied with different dental occlusions generated high standard deviations. Therefore, within the limitations of this pilot study, we could not conclusively associate dental occlusion to an instantaneous impact on the tested parameters. The posture changes that we detected could also have arisen from individual neuromuscular compensation; a possibility that must now be ruled-in, or out, by further research studies with a higher number of subjects.

BIM 기반 사용자 맞춤형 4D 및 5D 시스템 구현

BIM 기반 사용자 맞춤형 4D 및 5D 시스템 구현

SU‐F‐T‐297: Quality Assurance of Multiple Brain Metastases with Single Isocenter Using Measurement Guided Dose Reconstruction

Purpose:To evaluate the use of measurement guided dose reconstruction (MGDR) in quality assurance (QA) of stereotactic radiosurgery (SRS) of multiple brain metastases (MBM) planned with single isocenter (SI).Methods:Seven clinically approved multi‐isocenter MBM (MI‐MBM) plans were re‐optimized using SI (SI‐MBM) by coplanar volumetric arc therapy (VMAT) in Monaco v5.0 (Elekta CMS, Maryland Heights, MO, USA). These plans were delivered on an Elekta Agiltiy Linac and measured by OCTAVIUS 4D system with OCTAVIUS 1500 2D array (PTW, Freiburg, Germany). Measurements were repeated with a shift of the phantom by 5mm to double the detector resolution. 3D γ analysis in Verisoft 6.1 with 1.5mm/1.5%, 1.5mm/2% and 2mm/2% at local‐dose passing criteria and 20% dose suppression were made.Results:3D γ passing rates are 94.3±2.7%, 85.2±5.4% and 84±5.7% at 1.5mm/1.5%, 1.5mm/2% and 2mm/2% criteria.Conclusion:MGDR of OCTAVIUS 4D system provides adequate and efficient VMAT QA solution for SI‐MBM SRS. However, the results showed significant spatial dependence due to rapid dose fall‐off in radiosurgery. Further improvement in detector spatial resolution is desired. PTV margins should be carefully adopted for those MBM treated with single isocenter.

SU-F-T-584: Investigating Correction Methods for Ion Recombination Effects in OCTAVIUS 1000 SRS Measurements

Purpose: PTW's Octavius 1000 SRS array performs IMRT QA measurements with liquid filled ionization chambers (LICs). Collection efficiencies of LICs have been shown to change during IMRT delivery as a function of LINAC pulse frequency and pulse dose, which affects QA results. In this study, two methods were developed to correct changes in collection efficiencies during IMRT QA measurements, and the effects of these corrections on QA pass rates were compared. Methods: For the first correction, Matlab software was developed that calculates pulse frequency and pulse dose for each detector, using measurement and DICOM RT Plan files. Pulse information is converted to collection efficiency and measurements are corrected by multiplying detector dose by ratios of calibration to measured collection efficiencies. For the second correction, MU/min in daily 1000 SRS calibration was chosen to match average MU/min of the VMAT plan. Usefulness of derived corrections were evaluated using 6MV and 10FFF SBRT RapidArc plans delivered to the OCTAVIUS 4D system using a TrueBeam equipped with an HD- MLC. Effects of the two corrections on QA results were examined by performing 3D gamma analysis comparing predicted to measured dose, with and without corrections. Results: After complex Matlab corrections, average 3D gamma pass rates improved by [0.07%,0.40%,1.17%] for 6MV and [0.29%,1.40%,4.57%] for 10FFF using [3%/3mm,2%/2mm,1%/1mm] criteria. Maximum changes in gamma pass rates were [0.43%,1.63%,3.05%] for 6MV and [1.00%,4.80%,11.2%] for 10FFF using [3%/3mm,2%/2mm,1%/1mm] criteria. On average, pass rates of simple daily calibration corrections were within 1% of complex Matlab corrections. Conclusion: Ion recombination effects can potentially be clinically significant for OCTAVIUS 1000 SRS measurements, especially for higher pulse dose unflattened beams when using tighter gamma tolerances. Matching daily 1000 SRS calibration MU/min to average planned MU/min is a simple correction that greatly reduces ion recombination effects, improving measurements accuracy and gamma pass rates. This work was supported by PTW.

Investigating ion recombination effects in a liquid-filled ionization chamber array used for IMRT QA measurements.

PTW's Octavius 1000 SRS array performs IMRT quality assurance (QA) measurements with liquid-filled ionization chambers (LICs) to allow closer detector spacing and higher resolution, compared to air-filled QA devices. However, reduced ion mobility in LICs relative to air leads to increased ion recombination effects and reduced collection efficiencies that are dependent on Linac pulse frequency and pulse dose. These pulse parameters are variable during an IMRT delivery, which affects QA results. In this study, (1) 1000 SRS collection efficiencies were measured as a function of pulse frequency and pulse dose, (2) two methods were developed to correct changes in collection efficiencies during IMRT QA measurements, and the effects of these corrections on QA pass rates were compared. To obtain collection efficiencies, the OCTAVIUS 1000 SRS was used to measure open fields of varying pulse frequency, pulse dose, and beam energy with results normalized to air-filled chamber measurements. Changes in ratios of 1000 SRS to chamber measured dose were attributed to changing collection efficiencies, which were then correlated to pulse parameters using regression analysis. The usefulness of the derived corrections was then evaluated using 6 MV and 10FFF SBRT RapidArc plans delivered to the OCTAVIUS 4D system using a TrueBeam (Varian Medical Systems) linear accelerator equipped with a high definition multileaf collimator. For the first correction, matlab software was developed that calculates pulse frequency and pulse dose for each detector, using measurement and DICOM RT Plan files. Pulse information is converted to collection efficiency, and measurements are corrected by multiplying detector dose by ratios of calibration to measured collection efficiencies. For the second correction the MU/min in the daily 1000 SRS calibration was chosen to match the average MU/min of the volumetric modulated arc therapy plan. Effects of the two corrections on QA results were examined by performing 3D gamma analysis comparing predicted to measured dose, with and without corrections. Collection efficiencies correlated linearly to pulse dose, while correlations with pulse frequency were less defined, generally increasing as pulse frequency decreased. After complex matlab corrections, average 3D gamma pass rates improved by [0.07%,0.40%,1.17%] for 6 MV and [0.29%,1.40%,4.57%] for 10FFF using [3%/3 mm,2%/2 mm,1%/1 mm] criteria. Maximum changes in gamma pass rates were [0.43%,1.63%,3.05%] for 6 MV and [1.00%,4.80%,11.2%] for 10FFF using [3%/3 mm,2%/2 mm,1%/1 mm] criteria. On average, pass rates of simple daily calibration corrections were within 1% of complex matlab corrections. OCTAVIUS 1000 SRS ion recombination effects have little effect on 6 MV measurements. However, the effect could potentially be clinically significant for higher pulse dose unflattened beams when using tighter gamma tolerances, especially when small aperture sizes are used, as is common for SRS/SBRT. In addition, ion recombination effects are strongly correlated to changing MU/min, therefore MU/min used in daily 1000 SRS calibrations should be matched to the expected average MU/min of the IMRT plan.

EP-1562: VMAT pre-treatment verification using Octavius 4D system: from simple to more complex plans

EP-1562: VMAT pre-treatment verification using Octavius 4D system: from simple to more complex plans

EP-1543: Feasibility of MLC dosimetric leaf gap measurement using OCTAVIUS 4D system

EP-1543: Feasibility of MLC dosimetric leaf gap measurement using OCTAVIUS 4D system

Validity and Reliability of Spine Raster-stereography in Adolescent Idiopathic Scoliosis Patients

Introduction Previous studies have evaluated the validity and reliability of the Formetric-4D system. They concluded to a good accuracy compared with radiographs and a high intra- and inter-day reliability in healthy volunteer patients. However, to the best of our knowledge, the validity and reliability were not assessed on patients with Adolescent Idiopathic Scoliosis (AIS). Therefore, the aim of this study was to evaluate the validity and reliability of the Formetric 4D system on AIS adolescent patients with Cobb between 10¡ and 40¡ in terms of sagittal, frontal and transverse parameters. Materials and Methods This study included 35 AIS adolescents (male=13) aged 13.1 ± 2.0 years. To evaluate the validity of scoliosis angle (SA) provided by the Formetric-4D System, a comparison was performed with the Cobb Angle of major curve (CA) on a 2D EOS¨ radiography (XR). Mean differences of measurements computed by each system were evaluated using paired Student t-test and Pearson correlation coefficient. To evaluate interrater reliability three repeated-measurements were independently performed in a neutral orthostatic position using the Formetric-4D System by two operators the same day. To evaluate the intrarater reliability three more repeated-measurements were performed by the first operator one week later. The parameters measured were vertebra surface rotation, thoracic kyphosis, lumbar lordosis, pelvic obliquity, trunk length and the scoliosis angle. The data analyses used were Intraclasse Correlation Coefficients (ICC). Results The 2D radiographic Cobb Angle (CA) and its rasterstereographic equivalent Scoliosis Angle (SA) were strongly correlated (R = 0,70) with a non-significant difference. The ICC for intrarater (same day: ICC (1, 1), n = 35, one week later: ICC (1, 3), n = 29) as interrater reliability coefficients (ICC (3, 3), n = 16) were excellent (ICC > 0.75) for all variables except for pelvic obliquity with the highest for sagittal and rotation parameters and lowest for the pelvis obliquity. Conclusion This study showed that the Formetric 4D system allows evaluating AIS patients with a good validity and an overall excellent intra- and interrater reliability. Based on these results, this automatic, fast and non-invasive system will not replace XR clinical analysis but it can reduce the exposure to radiation for the patients and can improve the monitoring of scoliosis evolution with no limits of use, no risks for patients and at lower price than XR.

Reliability evaluation of the roll motion under the wind and irregular beam waves

This paper intends to study the stochastic response and reliability of the roll motion under the action of wind and wave excitation. The roll motion in random beam seas is described by a four-dimensional (4D) Markov dynamic system whose probabilistic properties are governed by the Fokker–Planck (FP) equation. The 4D path integration (PI) method, an efficient numerical technique based on the Markov property of the 4D system, is applied in order to solve the high dimensional FP equation and then the stochastic statistics of the roll motion are derived. Based on the obtained response statistics, the reliability evaluation of the ship stability is performed and the effect of wind action is studied. The accuracy of the 4D PI method and the reliability evaluation is assessed by the versatile Monte Carlo simulation (MCS) method.

PTW 729 detector array degradation of response over time following VMAT pre-treatment quality assurance using the Octavius 4D system

PTW 729 detector array degradation of response over time following VMAT pre-treatment quality assurance using the Octavius 4D system

Europeans shine in weather forecasting

The US global model lags the performance of two European competitors in predicting weather up to two weeks ahead.

Design and Implementation of Pneumatic Motion Base for 4D Home Theater

Home Entertainment system is recently being offered by Home Theater & Smart TV with contents service. Also, console game is being played in the media like in TV. The usage of 4D as the main technology in entertainment industry has mostly been limited in Theme Park, Amuse Park, Theater, and contents for Movie and Animation. Some simulation systems for game has been developed but they were made mostly by using electric or hydraulic motion system which cause high power consumption and have a restriction of place for install. The paper is attempted to build Home Entertainment system which makes users feel realistic contents by developing 4D systems for Home Entertainment rather than before. 4D control S/W in which user can insert and edit 4D effects on contents of all areas such as game, movie, and broadcasting is developed. Also, built-in pneumatic cylinder in 4D system which can be easily controlled and managed in home is developed.

Conformal a-anomaly of some non-unitary 6d superconformal theories

We compute the conformal anomaly a-coefficient for some non-unitary (higher derivative or non-gauge-invariant) 6d conformal fields and their supermultiplets. We use the method based on a connection between 6d determinants on S^6 and 7d determinants on AdS_7. We find, in particular, that (1,0) supermultiplet containing 4-derivative gauge-invariant conformal vector has precisely the value of a-anomaly as attributed in arXiv:1506.03807 (on the basis of R-symmetry and gravitational 't Hooft matching) to the standard (1,0) vector multiplet. We also show that higher derivative (2,0) 6d conformal supergravity coupled to exactly 26 (2,0) tensor multiplets has vanishing a-anomaly. This is the 6d counterpart of the known fact of cancellation of the conformal anomaly in the 4d system of N=4 conformal supergravity coupled to 4 vector N=4 multiplets. In the case when 5 of tensor multiplets are chosen to be ghost-like and the conformal symmetry is spontaneously broken by a quadratic scalar constraint the resulting IR theory may be identified with (2,0) Poincare supergravity coupled to 21=26-5 tensor multiplets. The latter theory is known to be special: it is gravitational anomaly free and results upon compactification of 10d type IIB supergravity on K3.

Filter models for prediction of stochastic ship roll response

In this paper, the shaping filter technique is introduced to study the stochastic roll response of a vessel in random beam seas. Specifically, the roll motion is described as a single-degree-of-freedom (SDOF) model in which the stationary random wave excitation term is approximated as the output of a shaping filter, i.e. a filtered white noise process. Therefore, the original SDOF model can be extended into a four-dimensional (4D) and a six-dimensional (6D) dynamic system, respectively, when this second-order nonlinear differential equation couples with the second-order linear filter and the fourth-order linear filter used to model the random wave excitation. Basically, the fourth-order linear filter provides a better approximation, but the subsequent dynamic system would be more complicated to tackle. In this regard, the 4D coupled system can be viewed as a Markov system whose probability properties are governed by the Fokker–Planck (FP) equation. Furthermore, the 4D path integration (PI) method, an efficient approximate technique based on the Markov property of the dynamic system, is applied to solve the 4D FP equation and then the response statistics are derived. In contrast, the statistics of the roll response in the 6D extended system are evaluated directly by a 6D Monte Carlo simulation. The advantages of the 4D PI method as well as the feasibility of simplifying the 6D system by the 4D system in terms of determining the statistics of high-level roll response are demonstrated through various cases corresponding to different sea states. Furthermore, the influence of external excitations on the statistics of high roll response levels is also illustrated by these cases.

SU‐E‐T‐790: Validation of 4D Measurement‐Guided Dose Reconstruction (MGDR) with OCTAVIUS 4D System

Purpose:To validate the MGDR of OCTAVIUS 4D system (PTW, Freiburg, Germany) for quality assurance (QA) of volumetric‐modulated arc radiotherapy (VMAT).Methods:4D‐MGDR measurements were divided into two parts: 1) square fields from 2×2 to 25×25 cm2 at 0°, 10° and 45° gantry, and 2) 8 VMAT plans (5 nasopharyngeal and 3 prostate) collapsed to gantry 40° in QA mode in Monaco v5.0 (Elekta, CMS, Maryland Heights, MO) were delivered on the OCTAVIUS 4D phantom with the OCTAVIUS 1500 detector plane perpendicular to either the incident beam to obtain the reconstructed dose (OCTA4D) or the 0° gantry axis to obtain the raw doses (OCTA3D) in Verisoft 6.1 (PTW, Freiburg, Germany). Raw measurements of OCTA3D were limited to < 45° gantry to avoid >0.5% variation of detector angular response with respect to 0° gantry as determined previously. Reconstructed OCTA4D and raw OCTA3D doses for all plans were compared at the same detector plane using γ criteria of 2% (local dose)/2mm and 3%/3mm criteria.Results:At gantry 0° and 10°, the γ results for all OCTA4D on detector plane coinciding with OCTA3D were over 90% at 2%/2mm except for the largest field (25×25 cm2 ) showing >88%. For square field at 45° gantry, γ passing rate is > 90% for fields smaller than 15x 15cm2 but < 80% for field size of 20 x20 cm2 upward. For VMAT, γ results showed 94% and 99% passing rate at 2%/2mm and 3%/3mm, respectively.Conclusion:OCTAVIUS 4D system has compromised accuracy in reconstructing dose away from the central beam axis, possibly due to the off‐axis softening correction and errors of the percent depth dose data necessary as input for MGDR. Good results inVMAT delivery suggested that the system is relatively reliable for VMAT with small segments.

TH-CD-304-10: A Method for Correcting Ion Recombination Effects in OCTAVIUS 1000 SRS Measurements

Purpose: PTW's Octavius 1000 SRS array performs IMRT QA measurements with liquid filled ionization chambers to allow closer detector spacing and higher resolution. Increased density of liquid relative to air, leads to increased ion recombination effects, which are proportional to dose/pulse experienced at the detectors. During IMRT QA, dose/per pulse will vary across the array, leading to varying collection efficiencies. Magnitudes of recombination effects were investigated and a method was developed to correct them in QA measurements. Methods: The OCTAVIUS 1000 SRS was used to measure different IMRT plans using varying dose/pulse and results were normalized to air filled chamber measurements to obtain collection efficiencies. Regression analysis was performed to relate collection efficiency to dose/pulse. Matlab software was developed to correct IMRT QA measurements using these correlations. Measurements were performed on a Truebeam equipped with high-definition MLC, using 6MV and 10FFF RapidArc plans. Plans were measured in the OCTAVIUS 4D system, which measures dose in time intervals. Dose/time was converted to dose/pulse using pulse repetition information. Collection efficiency to dose/pulse correlations were used to correct measured dose. 3D gamma analysis was performed on plans with and without corrections. Results: Liquid filled ionization chamber collection efficiency correlated linearly to dose/pulse with slopes of 2.15%/(mGy/pulse) for 6MV and 5.74%/(mGy/pulse) for 10FFF. After corrections, average gamma pass rates improved by [0.02%,0.06%,0.24%] for 6MV and [0.19%,0.54%,2.01%] for 10FFF using [3%/3mm,2%/2mm,1%/1mm] criteria. Maximum changes in gamma pass rates were [0.1%,0.3%,0.5%] for 6MV and [0.4%,0.8%,5.1%] for 10FFF using [3%/3mm,2%/2mm,1%/1mm] criteria. Conclusion: OCTAVIUS 1000 SRS ion recombination effects have little effect on 6MV measurements. However, the effect is larger for higher dose/pulse unflattened beams when using tighter gamma tolerances, as is common for SRS/SBRT. This researched was supported by PTW.

SU‐E‐T‐202: Comparison of 4D‐Measurement‐Guided Dose Reconstructions (MGDR) with COMPASS and OCTAVIUS 4D System

Purpose:To cross‐validate the MGDR of COMPASS (IBA dosimetry, GmbH, Germany) and OCTAVIUS 4D system (PTW, Freiburg, Germany).Methods:Volumetric‐modulated arc plans (5 head‐and‐neck and 3 prostate) collapsed to 40° gantry on the OCTAVIUS 4D phantom in QA mode on Monaco v5.0 (Elekta, CMS, Maryland Heights, MO) were delivered on a Elekta Agility linac. This study was divided into two parts: (1) error‐free measurements by gantry‐mounted EvolutionXX 2D array were reconstructed in COMPASS (IBA dosimetry, GmbH, Germany), and by OCTAVIUS 1500 array in Versoft v6.1 (PTW, Freiburg, Germany) to obtain the 3D doses (COM4D and OCTA4D). COM4D and OCTA4D were compared to the raw measurement (OCTA3D) at the same detector plane for which OCTAVIUS 1500 was perpendicular to 0° gantry axis while the plans were delivered at gantry 40°; (2) beam steering errors of energy (Hump=‐2%) and symmetry (2T=+2%) were introduced during the delivery of 5 plans to compare the MGDR doses COM4D_Hump (COM4D_2T), OCTA4D_Hump (OCTA4D_2T), with raw doses OCTA3D_Hump (OCTA3D_2T) and with OCTA3D to assess the error reconstruction and detection ability of MGDR tools. All comparisons used Υ‐criteria of 2%(local dose)/2mm and 3%/3mm.Results:Averaged Υ passing rates were 85% and 96% for COM4D,and 94% and 99% for OCTA4D at 2%/2mm and 3%/3mm criteria respectively. For error reconstruction, COM4D_Hump (COM4D_2T) showed 81% (93%) at 2%/2mm and 94% (98%) at 3%/3mm, while OCTA4D_Hump (OCTA4D_2T) showed 96% (96%) at 2%/2mm and 99% (99%) at 3%/3mm. For error detection, OCTA3D doses were compared to COM4D_Hump (COM4D_2T) showing Υ passing rates of 93% (93%) at 2%/2mm and 98% (98%), and to OCTA4D_Hump (OCTA4D _2T) showing 94% (99%) at 2%/2mm and 81% (96%) at 3%/3mm, respectively.Conclusion:OCTAVIUS MGDR showed better agreement to raw measurements in both error‐ and error‐free comparisons. COMPASS MGDR deviated from the raw measurements possibly owing to beam modeling uncertainty.

Application of octavius 4D system in volumetric modulated arc therapy dose verification

Objective To study the feasibility of dose verification with Octavius 4D system in volumetric modulated arc therapy (VMAT). Methods Twenty patients were treated with the VMAT. Their treatment plans were performes and then acquired the measured data with the Octavius 4D system. In addition, the treatment plans are used in the CT phantom for Octavius 4D system, and acquire the simulated data. We use the γ pass rate to analysis the measured and simulated results for the conditions : the dose deviations are 2%3%5%, the displacement deviations are 2 mm/3 mm/5 mm and the thresholds are 5% 10%, and got the Gamma pass rate and fitness of profile curve. Results The distributions of measured and simulated dose are matched well, and the fitness of profile curve are also matched well. The averaged Gamma pass rate is 97. 78% in the case 3 mm 3% 10%. Conclusions Octavius 4D system can meet the dose verification for VMAT treatment. The measured plane is always following the rotating frame and perpendicular to the beam. Key words: Volumetric modulated arc therapy; Octavius 4D system; Dose veriftcation

Complex transient dynamics of hidden attractors in a simple 4D system**Project supported by the National Natural Science Foundation of China (Grant No. 51277017), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2012583), and the Fundamental Research Funds for the Central Universities of China (Grant No. NS2014038).

A simple four-dimensional system with only one control parameter is proposed in this paper. The novel system has a line or no equilibrium for the global control parameter and exhibits complex transient transition behaviors of hyperchaotic attractors, periodic orbits, and unstable sinks. Especially, for the nonzero-valued control parameter, there exists no equilibrium in the proposed system, leading to the formation of various hidden attractors with complex transient dynamics. The research results indicate that the dynamics of the system shows weak chaotic robustness and depends greatly on the initial states.