RESUMO
With the utilization of diffusion tensor information of image voxels, a novel MRF (Markov Random Field) segmentation algorithm was proposed for diffusion tensor MRI (DT-MRI) images benefitted from the introduction of Frobenius norm. The comparison of the segmentation effects between the proposed algorithm and K-means segmentation algorithm for DT-MRI image was made, which showed that the new algorithm could segment the DT-MRI images more accurately than the K-means algorithm. Moreover, with the same segmentation algorithm of MRF, better outcomes were achieved in DT-MRI than in conventional MRI (T2WI) image.
Assuntos
Humanos , Algoritmos , Imagem de Difusão por Ressonância Magnética , Métodos , Interpretação de Imagem Assistida por Computador , Métodos , Reconhecimento Automatizado de PadrãoRESUMO
As a powerful global optimization approach, genetic algorithms (GA) can solve a variety of optimization problems in which the objective function is discontinuous, non-differentiable, or highly non-linear, to produce high convergence speed and vast search space. In this thesis, GA is used to optimize the beam weights of intensity modulated radiation therapy (IMRT) inverse planning, and 2D and 3D isodose contour as well as dose volume histogram (DVH) are used to evaluate the treatment plan. Also presented in this thesis are the results of calculation with discussions.
Assuntos
Humanos , Algoritmos , Modelos Teóricos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Métodos , Radioterapia Conformacional , Métodos , Padrões de ReferênciaRESUMO
<p><b>UNLABELLED</b>To study the method for dose calculation and beam weight optimization of intensity-modulated radiation therapy (IMRT).</p><p><b>METHODS</b>The IMRT dose calculation model based on two-dimensional convolution was constructed, the program of dose calculation and beam weight optimization with genetic algorithm was written with Visual c#.Net, and the optimization results were analyzed.</p><p><b>RESULTS</b>Genetic algorithm optimization of beam weights can produce highly conformal dose distributions within a clinically acceptable computation time.</p><p><b>CONCLUSION</b>Genetic algorithm is valid and efficient in IMRT beam weight optimization, which may facilitate IMRT treatment planning.</p>
Assuntos
Humanos , Algoritmos , Modelos Estatísticos , Modelos Teóricos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Métodos , Radioterapia Conformacional , Métodos , Padrões de ReferênciaRESUMO
This paper introduces the constitution and fabrication of the new head and neck stereotactic conformal radiotherapy system. It remedies the shortages in the head and neck stereotactic conformal radiotherapy at present and it is deserved to be popularized in clinical applications.
Assuntos
Humanos , Desenho de Equipamento , Cabeça , Diagnóstico por Imagem , Cirurgia Geral , Neoplasias de Cabeça e Pescoço , Diagnóstico por Imagem , Cirurgia Geral , Pescoço , Diagnóstico por Imagem , Cirurgia Geral , Radiografia , Radiocirurgia , Radioterapia ConformacionalRESUMO
In this paper, two new concepts of DR (Dose Repulsion) and DG (Dose Gravitation) are presented with their calculation formulas. For the problem of selecting beam arcs in x-knife radiotherapy Planning system, a mathematics model of constrained optimization has been built. Furthermore, we have produced a feasible project of automatic selecting optimized beam arcs plan using SA (Simulated Annealing) arithmetic based on the distribution of the fields of DR and DG in the reduced phase space.