A Quantitative Analysis of Dose Distributions of Two Tangential Whole Breast Irradiation Techniques

We compared DVHs （dose volume histograms） of two tangential irradiation techniques for whole breast RT （radiotherapy） CT （computed tomography） based 2D （two dimensional） technique with wedge filters and 3D CRT （three dimensional conformal radiotherapy） with segmented fields. These two modalities are commonly used in external beam radiotherapy of breast cancer in Clinical Center Nis, Clinic of Oncology, Serbia. Therapy plans that employed two techniques were generated for eighteen patients. Dosimetric outcomes of each technique were investigated. The maximum dose of breast CTV was significantly reduced from 55.83 Gy for 2D to 54.1 Gy for 3D CRT. Also, the maximum dose of lung tissue decreased from 51.81 Gy for 2D to 49.61 Gy for 3D. The dose conformity and uniformity were much better with 3D CRT segmented field technique.

GREEN'S FUNCTIONS FOR 2D PROBLEMS OF ANISOTROPIC PIEZOELECTRIC MATERIAL WITH A STRIP REGION

By using Stroh's formalism and the conformal mapping technique,we derive the simple ex- plicit elastic fields of a generalized line dislocation and a generalized line force in a general anisotropic piezo- electric strip with fixed surfaces,which are two fixed conductor electrodes.The solutions obtained are usually considered as Green's functions which play important roles in the boundary element methods.The Coulomb forces of the distributed charges along the region boundaries on the line charge q at z^0 are analysed in detail. The results are valid not only for plane and antiplane problems but also for the coupled problems between in- plane and outplane deformations.

Degenerate scale problem in antiplane elasticity or Laplace equation for contour shapes of triangles or quadrilaterals

This paper provides several solutions to the degenerate scale for the shapes of triangles or quadrilaterals in an exterior boundary value problem （BVP） of the antiplane elasticity or the Laplace equation. The Schwarz-Christoffel mapping is used throughout. It is found that a complex potential with a simple form in the mapping plane satisfies the vanishing displacement condition （or w ---- 0） along the boundary of the unit circle when the dimension R reaches its critical value 1. This means that the degenerate size in the physical plane is also achieved. The degenerate scales can be evaluated from the partic- ular integrals depending on certain parameters in the mapping function. The numerical results of degenerate sizes for the shapes of triangles or quadrilaterals are provided.

THE GENERAL SOLUTION FOR THE STRESS PROBLEM OF CIRCULAR CYLINDRICAL SHELLS WITH AN ARBITRARY CUTOUT

In this paper a complex variable analytic method for solving stress concentrations in the circular cylindrical shell is proposed. The problem to be solved can be summarized into the solution of an infinite algebraic equation series. The solution can be normal and effective by means of this method. Numerical results for stress concentrations in the shell with a circular, elliptic cutout are graphically presented.

Performance prediction of four-contact vertical Hall-devices using a conformal mapping technique

Instead of the conventional design with five contacts in the sensor active area, innovative vertical Hall devices （VHDs） with four contacts and six contacts are asymmetrical in structural design but symmetrical in the current flow that can be well fit for the spinning current technique for offset elimination. In this article, a conformal mapping calculation method is used to predict the performance of asymmetrical VHD embedded in a deep n-well with four contacts. Furthermore, to make the calculation more accurate, the junction field effect is also involved into the conformal mapping method. The error between calculated and simulated results is less than 5% for the currentrelated sensitivity, and approximately 13% for the voltage-related sensitivity. This proves that such calculations can be used to predict the optimal structure of the vertical Hall-devices.