Relativistic Optimization Force Concept for gEUD Biological Optimization and Novel a-value Selection Viewpoint

Generalized equivalent uniform dose (gEUD) optimization is a biological optimization method used for intensity modulated radiation therapy (IMRT). Although parametric analyses have been widely reported, the use of parameter a-value in the optimization method remains elusive. This study aims to clarify the mathematical characteristics of the gEUD and to provide effective a-value selection. The gEUD is typically obtained using a differential dose volume histogram (DVH). This can be rewritten using a cumulative DVH (cDVH) and applied to variational analysis. The equivalence between the gEUD and the dose is then obtained; a low or high a-value corresponds to a wide or narrow dose range of optimization, respectively. Next, we focused on the gEUD curve behavior against a-value shifts and it retained its curve characteristics despite optimization. Using differential geometry, this curve shift can be considered as a geodesic deviation between pre- and post-optimization by a relativistic optimization force. The total action enacted by the force includes the curvature of the gEUD curve. This idea provides a novel viewpoint that the curvature of the gEUD curve is influenced by the optimization effect. The curvature stationary point of the gEUD curve (the vertex point, a = a_k) is expected to be a special point that leads to effective a-value selection. Eleven head and neck patient cases were used to verify the curvature effect. We used the Photon Optimizer (PO) of Eclipse for optimization and focused the upper gEUD to simplify the dose constraint for the organ at risk (OAR) that requires balancing of the overlapped planning target volume(PTV). Static seven-field IMRT was used for optimization, changing the a-value of the affected side of the parotid and retaining PTV D95% = 70Gy at the different a-value optimization. Finally, cDVH shift (ΔDVH), gEUD shift (ΔgEUD), their average values, and a_k were evaluated. The a = a_k optimization showed an intermediate effect of lower and higher a-values on ΔDVH, ΔgEUD, and their averages. “Lower” (a=0.5/1.0/2.0/3.0), “middle” (a=4.0/5.0/6.0/8.0/10/a_k), and “higher” (a=12/15/20/40) were defined using a=a_k as a base point. Lower a-value optimization was effective for the low-dose region and weakly affected the whole range of cDVH weight. In contrast, higher a-value optimization addressed the high-dose region and strongly affected the high-dose range of the cDVH weight as theoretically predicted. In addition, the middle range of the a-value optimization induced a decrease in the clinically important middle-to-high dose range, which retained the high dose of the PTV. Interestingly, the average ΔDVH and ΔgEUD corresponded exponentially to the curvature and the gradient of the gEUD curve. Using our relativistic optimization force concept, gEUD optimization is represented as a gEUD curve shift, highlighting that the curvature of the gEUD curve is the essence of gEUD optimization. The curvature stationary point (a = a_k), namely the vertex point of the gEUD curve, played an intermediate role in the low-to-high a-value condition. We can effectively select a lower/middle/higher a-value from a base point of a = a_k under clinically complex optimization situation.

Development of helmet mold design system using 3D anthropometric analysis

Purpose The purpose of this paper is to develop a software can generate helmet mold from three-dimensional (3D) human body scan data. Design/methodology/approach An algorithm has been developed to divide data into arbitrary number of groups considering the width, length and height of head using the standard normal distribution theory. A basic helmet mold is generated automatically based on the shape of representative convex hull for each group. Findings It is possible to analyze the 3D human body scan data of groups with various characteristics and apply them to mass customized production of helmet. Practical implications This methodology can be applied for designing other products related to the head shape such as goggles and masks by varying the measurement items of the head. Social implications This methodology will enable mass customized production centered on consumers in the production and design of various equipment and goods to be worn on the head. Originality/value An algorithm has been developed to define the vertex point, which is the limit of scan data, for the analysis of 3D human body scan data scan data. In addition, a system was developed that can mass-produce customized products by effectively dividing groups while taking into account the physical characteristics of consumers.

Functional Classification of the Medial Ulnar Collateral Ligament: An In Vivo Kinematic Study With Computer-Aided Design

Background: It has been widely accepted that the anterior and posterior bundles of the medial ulnar collateral ligament (MUCL) tighten at extension and flexion, respectively. However, this belief is based on anatomic data acquired from cadaveric studies. The advancement of 3-dimensional (3D) model technology has made possible the simulation of dynamic movement that includes each ligament bundle fiber to analyze its functional properties. To date, no study has analyzed ligament kinematics at the level of the fibers while also focusing on their functional properties. Purpose: To propose a new classification for functional properties of the MUCL based on its kinematic pattern. Study Design: Descriptive laboratory study. Methods: Five healthy elbow joints were scanned by use of computed tomography, and 3D models were rendered and translated into vertex points for further mathematical analysis. The humeral origin and ulnar insertion of the MUCL fiber groups were registered. Each vertex point on the origin side was randomly connected to the insertion side, with each pair of corresponding points defined as 1 ligament fiber. Lengths of all the fibers were measured at 1° increments of elbow range of motion (ROM). Ligament fibers were grouped according to their patterns. Mean coverage area for each group, expressed as the percentage of ligament fibers per group to the total number of fibers, was calculated. Results: Four major bundle groups were found based on fiber length properties. Kinematic simulation showed that each group had a different kinematic function throughout elbow ROM. Mean coverage area of groups 1, 2, 3, and 4 was 8% ± 4%, 10% ± 5%, 42% ± 6%, and 40% ± 8%, respectively. Each group acted as a dominant stabilizer in certain arcs of motion. Reciprocal activity was observed between groups 1 and 3 along with groups 2 and 4 to produce synergistic properties of maintaining elbow stability. Conclusion: Detailed analysis of fibers of the MUCL allows for further understanding of its kinematic function. This study provides MUCL group coverage area and kinematic function for each degree of motion arc, allowing selective reconstruction of the MUCL according to mechanism of injury. Clinical Relevance: Understanding the dominant functional fibers of the MUCL will benefit surgeons attempting MUCL reconstruction and will enhance further anatomic study.

Missing observations: The loss in relative A-, D- and G-efficiency

The loss in Relative A-, D- and G-efficiency due to missing single or multiple observations is studied using cuboidal designs associated with response models. Higher losses in Relative A- and D-efficiencies are attributed to missing vertex points. The absence of one or two center points does not affect any of Relative A-, D- and G-efficiency, but when its absence is in combination with either a vertex or axial point, there is some negative effect on the design efficiency resulting in some percentage loss in Relative efficiency. The loss in relative efficiency is higher when the missing center point is in combination with missing vertex point. Losses in Relative A- and D-efficiencies are generally higher than losses in Relative G-efficiency. In fact, Relative G-efficiency is mildly affected by the missing vertex or axial point or both.

Development of Sketch-Based 3-D Modeling System for Rapid Generation and Evaluation of Automotive Seat Shape Using Reference Models

Seat style designers transform their ideas into 3-D forms using creative, iterative modeling processes to quickly evolve their designs from concept to reality, while refining the design details of the seat shape. Although the recent introduction of computer-aided styling systems to the design process has greatly enhanced designers' productivity, they still prefer to ideate using “pen and paper.” Here, we propose a sketch-based 3-D modeling system that enables designers to rapidly and intuitively create a seat shape by applying a 2-D sketch to a normalized seat reference model and then evaluating the newly designed model. For this purpose, we describe three modeling techniques that support interactive shape editing: curve manipulation using pen strokes, vertex point manipulation, and tangent vector manipulation. In addition, we propose three methods for the design and functional evaluation of an automotive seat, checking for interference between a seat skin and its frame, checking for foldability among seat components with regard to their positioning, and checking for coupling between a seat model and a digital human body.

Semi Automatic Retargeting for Facial Expressions of 3D Characters with Fuzzy logicBased on Blendshape Interpolation

To produce a 3D virtual character's face expression of human’s natural face expressions, facial motion capture is the technique considered to be the most effective one, especially in terms of production speed. However, there are still some results showing that the expression is not so expressive, especially on the side of the 3D character which has a different facial features than the real models regarding to the application of it. In this research, the correction of the basic expressions of faces in the process of facial motion retargeting was done by using blendshape interpolation method that was based on fuzzy logic. Blendshape interpolation method is the method used to combine multiple shapes into one blend with the concept of interpolation. In this research, the process of blendshape meets the concept of linear interpolation which the movement of a point of vertexon blendshape used straight lines . Blendshape method will be run as a proofreader on the results of retargeting process. Theweighting of blendshape will be assigned automatically from the results of the calculation of fuzzy logic, which refers to the input of the marker position of the facial motion retargeting. This weight is then used to provide improvements to create more expressive expressions. This process will be easier and faster to do than doing customize one by one at the vertex point manually. To avoid the appearance of irregular motion (haphazard movement), it is necessary to give the limitation of the weight (weight constraint) with range of [0,1].Keywords : Blendshape, retargeting, fuzzy logic, facial motion capture.

Second-order properties and central limit theory for the vertex process of iteration infinitely divisible and iteration stable random tessellations in the plane

The point process of vertices of an iteration infinitely divisible or, more specifically, of an iteration stable random tessellation in the Euclidean plane is considered. We explicitly determine its covariance measure and its pair-correlation function, as well as the cross-covariance measure and the cross-correlation function of the vertex point process and the random length measure in the general nonstationary regime. We also give special formulae in the stationary and isotropic setting. Exact formulae are given for vertex count variances in compact and convex sampling windows, and asymptotic relations are derived. Our results are then compared with those for a Poisson line tessellation having the same length density parameter. Moreover, a functional central limit theorem for the joint process of suitably rescaled total edge counts and edge lengths is established with the process (ξ, tξ), t > 0, arising in the limit, where ξ is a centered Gaussian variable with explicitly known variance.

Second-order properties and central limit theory for the vertex process of iteration infinitely divisible and iteration stable random tessellations in the plane

The point process of vertices of an iteration infinitely divisible or, more specifically, of an iteration stable random tessellation in the Euclidean plane is considered. We explicitly determine its covariance measure and its pair-correlation function, as well as the cross-covariance measure and the cross-correlation function of the vertex point process and the random length measure in the general nonstationary regime. We also give special formulae in the stationary and isotropic setting. Exact formulae are given for vertex count variances in compact and convex sampling windows, and asymptotic relations are derived. Our results are then compared with those for a Poisson line tessellation having the same length density parameter. Moreover, a functional central limit theorem for the joint process of suitably rescaled total edge counts and edge lengths is established with the process (ξ,tξ),t> 0, arising in the limit, where ξ is a centered Gaussian variable with explicitly known variance.

Lip Posture Following Debonding of Labial Appliances Based on Conventional Profile Photographs

Objective: To assess changes in lip posture following debonding of labial appliances on the basis of a new soft tissue analysis performed by computerized tools with the use of conventional nonstandardized profile photographic pictures. Materials and Methods: Profile photographs of 33 patients were taken just before and just after debonding of labial brackets. Pictures were examined twice through custom-made analysis in which Viewbox software was used. The validity of this new analysis was assessed in a preliminary study. A reference line was constructed between the center of the tragus and the outer canthus. The point where this elongated line intersected with the profile was coined nasion-modified and served as the vertex point for angles used to evaluate the prominence of the lips. The final position of the lines was determined when they were tangent to the appropriate landmarks. Analysis of variance (ANOVA) and t-tests for paired differences were used. Results: The reproducibility of this photoanalysis was confirmed in the preliminary study, in that no significant differences were found between measurements (P < .05). No statistically significant differences were noted in lip posture between pre-debonding and post-debonding pictures (P < .05). Conclusions: In keeping with the design of this study, soft tissue profile photoanalysis showed that the presence of bonded labial appliances had no effect on lip posture. (Angle Orthod. 2009:79; )

The Study on the Linking-Up of Free-Form Surface Fiber Placement Track Based on Mesh Creating

When using meshing creating method of FP (fiber placement) track, once the track point falls at some vertex point of mesh element, in the meantime the vertex point happens to be shared by several mesh elements, there needs a reasonable calculation method to select next mesh element which the FP track will pass through. Then it comes to the problem on linking of FP tracks. In order to solve it, in this paper, the author puts forward a new method, in which parallel projection theory is used, project need analytical mesh element and FP reference vector to a sound projective plane, on which the mesh element be selected and the FP track be calculated, then the FP track would be projected back to the placement surface. Program using this method realized a reasonable joint at the shared vertex point of meshing elements, which the FP direction has little change, and the mutation of track doesn’t come forth. So, the correctness of the method, which putted forward in this paper, is proved.