Wyniki wyszukiwania - BazTech

1

Three dimensional conformal radiotherapy for synchronous bilateral breast irradiation using a mono iso-center technique

Mani K. R., Basu S., Bhuiyan M. A., Ahmed M. A., Sumon M. A., Haque K. A., Sengupta A. K., Un Nabi M. R., Das K. J. M.

Polish Journal of Medical Physics and Engineering

|

2017

|

Vol. 23, Iss. 2

15--19

EN

Objective: The purpose of this study is to demonstrate the synchronous bilateral breast irradiation radiotherapy technique using a single isocenter. Materials and Methods: Six patients of synchronous bilateral breast were treated with single isocenter technique from February 2011 to June 2016. All the patients underwent a CT-simulation using appropriate positioning device. Target volumes and critical structures like heart, lung, esophagus, thyroid, etc., were delineated slice by slice in the CT data. An isocenter was placed above the sternum on the skin and both medial tangential and lateral tangential of the breast / chest wall were created using asymmetrical jaws to avoid the beam divergence through the lung and heart. The field weighting were adjusted manually to obtain a homogenous dose distribution. The planning objectives were to deliver uniform doses around the target and keep the doses to the organ at risk within the permissible limit. The beam energy of 6 MV or combination of 6 MV and 15 MV photons were used in the tangential fields according to the tangential separation. Boluses were used for all the mastectomy patients to increase the doses on the chest wall. In addition to that enhanced dynamic wedge and field in field technique were also used to obtain a homogenous distribution around the target volume and reduce the hot spots. The isocenter was just kept on the skin, such that the beam junctions will be overlapped only on the air just above the sternum. Acute toxicity during the treatment and late toxicity were recorded during the patient’s follow-up. Results: During the radiotherapy treatment follow-up there were no acute skin reactions in the field junctions, but one patient had grade 1 esophagitis and two patients had grade 2 skin reactions in the chest wall. With a median follow-up of 38.5 months (range: 8 - 49 months), no patients had a local recurrence, but one patients with triple negative disease had a distant metastases in brain and died after 28 months. Conclusions: We were able to successfully treat the synchronous bilateral breast using single isocenter radiotherapy while keeping the lung and heart doses within the acceptable dose limits. During the treatment follow-up there were no symptoms of acute skin reactions in the field junction.

2

P-wave interaction with a pair of rigid strips embedded in an orthotropic strip

Basu S., Mandal S. C.

Journal of Theoretical and Applied Mechanics

|

2016

|

Vol. 54 nr 2

579--592

EN

The present paper is concerned with the problem of scattering of the P-wave by two co- -planer finite rigid strips placed symmetrically in an infinitely long orthotropic strip. Using the Hilbert transform technique, the mixed boundary value problem has been reduced to the solution of dual integral equations which has finally been reduced to the solution of a Fredholm integral equation of the second kind. Solving this integral equation numerically, stress intensity factors have been calculated at the inner and outer edges of the rigid strips, and the vertical displacement outside the strips has been calculated and plotted graphically to show the effect of material orthotropy.

3

Reflection and refraction of generalized temperature rate dependent thermoelastic waves at an interface between two semi-infinite media

Lahiri A., Das N. C., Bera M. B., Basu S.

International Journal of Applied Mechanics and Engineering

|

2011

|

Vol. 16, no 4

1051-1069

EN

The problem of reflections and refractions of the generalized temperature rate dependent thermoelastic waves at an interface between two semi-infinite media is considered. Amplitude ratios for the P- and SV- waves are found out by considering the mechanical and thermal boundary conditions at the interface. The results arrived at are analyzed and presented graphically.

4

Different Types of Linear Fuzzy Cellular Automata and their Applications

Basu S., Basu Sumita

Fundamenta Informaticae

|

2008

|

Vol. 87, nr 2

185-205

EN

A linear array of interconnected fuzzy automaton is called linear fuzzy cellular automaton. It is shown that the language class of linear fuzzy cellular automata strictly contains the language class of linear cellular automata. This justifies the wide spread use of linear fuzzy cellular automaton as is evident from the literature. In this paper a special type of cellular automaton (CA) model is investigated. This CA model computes effect due to interaction of neighboring cells and effect due to external disturbance on the cells simultaneously. The transition due to both the effects may be represented by a single function which is the composition of two functions. Further it is shown that the class of language accepted by linear hybrid fuzzy cellular automata is included in the class of language accepted by linear hybrid fuzzy cellular automata with external input(HFCAI). HFCAI is useful for computing growth in evolutionary systems which are also affected by external cause.

5

An inconvenient “truth” about using sensible heat flux as a surface boundary condition in models under stably stratified regimes

Basu S., Van De Wiel B., Moene A., Steeneveld G.

Acta Geophysica

|

2008

|

Vol. 56, no. 1

88-99

EN

In single column and large-eddy simulation studies of the atmospheric bound-ary layer, surface sensible heat flux is often used as a boundary condition. In this paper, we delineate the fundamental shortcomings of such a boundary condition in the context of stable boundary layer modelling and simulation. Using an analytical approach, we are able to show that for reliable model results of the stable boundary layer accurate surface temperature prescription or prediction is needed. As such, the use of surface heat flux as a boundary condition should be avoided in stable condi-tions.

6

Rough grammar and rough language

Basu S.

Foundations of Computing and Decision Sciences

|

2003

|

Vol. 28, No. 3

129-141

EN

Formal languages ana grammars, wmcn generate tnem, cannot be successfully applied to model a real language, as they do not include the incorrectness and ambiguity of natural languages. Imprecision of real language can be incorporated in the formal language theory with the help of rough sets. Accordingly a precise language set is replaced by a pair of sets, which act as the two boundaries between which the actual set lies. In this paper we define a rough grammar and a rough language based on the concept of rough set A necessary and sufficient condition for the rough language to be a rough set is obtained. It is found that there may be 16 different classes of rough languages. A hierarchy among the different classes of languages is established.