Biplab Sarkar, Jyotirup Goswami, Ayan Basu and S. Sriramprasath
Dosimetric comparison of three dimensional conformal radiotherapy and intensity modulated radiotherapy in high grade gliomas
Treatment of high-grade gliomas continues to be frustrating for the clinician as the medial survival stands at a dismal 14.5 months for glioblastoma multiforme (GBM) with the current standard of care. Given the high dose and generous margins required to be irradiated, three dimensional conformal radiotherapy (3DCRT) has become standard practice. Radiation dose escalation beyond 60 Gy, by means of stereotactic or intensity modulated radiotherapy (IMRT) boost, has not yielded clinically significant benefits in terms of local control or survival. At the same time, the potential of IMRT to spare normal tissues such as the brain stem and the optic apparatus makes it an attractive tool for modern radiation oncologists in seeking to improve post-radiotherapy quality of life. At our centre, we have been treating a large number of cases of high grade glioma with 3DCRT and IMRT for the last several years. The present study has been an effort to understand any potential benefits that IMRT, even without dose escalation, can offer.
An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.
An investigation of unsteady hydromagnetic free convection flow of a viscous, incompressible and electrically conducting fluid past an impulsively moving vertical plate with Newtonian surface heating embedded in a porous medium taking into account the effects of Hall current is carried out. The governing partial differential equations are first subjected to the Laplace transformation and then inverted numerically using INVLAP routine of Matlab. The governing partial differential equations are also solved numerically by the Crank-Nicolson implicit finite difference scheme and a comparison has been provided between the two solutions. The numerical solutions for velocity and temperature are plotted graphically whereas the numerical results of skin friction and the Nusselt number are presented in tabular form for various parameters of interest. The present solution in special case is compared with a previously obtained solution and is found to be in excellent agreement.
Failure analysis of laminated composite plates for different mechanical, thermo mechanical and hygro-thermo mechanical loads for different ply thicknesses, stacking sequences, fiber orientation angles and composite material systems is presented in the paper. A comparative study of different failure theories is also presented in the paper. The effect of fiber orientation angles on the first ply failure load is also studied. A hybrid composite laminate is developed based on the first ply failure load which minimizes weight and cost. The last ply failure load based on fully discounted method is calculated for different stacking sequences. An optimum composite material system and laminate layup is studied for a targeted strength ratio which minimizes weight.