Study On Questions Of Treatment Planning System

A Gamma Knife radiosurgery treatment system is medical facility of radiotherapy using gamma rays. Gamma rays delivered from radiation sources in a dynamical focused Gamma knife system for whole body focus in the tumor while the radiation source rotates around the focus. Therefore, it can burn off the tumorous cells while reducing the damage to the normal tissue. Treatment planning system is an essential part of the radiosurgery treatment system. It is a computer-aided software system that helps physicians make treatment plans. This paper studies some key problems related to the treatment planning system, such as image segmentation, three-dimensional reconstruction, mesh simplification, dose distribution and optimization of automated treatment planning. And the paper also introduces the design and implementation of a treatment planning system, named CESC TPS.Three types of algorithms for image segmentation are studied in the paper, which are watershed-based approaches, level set-based approaches and region growing-based approaches. An implementation of region growing-based approach is presented in the paper. The segmentation starts from a seed specified by a user, and points in the neighborhood of the seed are added to the target field if they satisfy the given rules. The procedure continues until all pixels in the neighborhood of the seed are evaluated.Reconstruction of a geometry model for anatomical structure is essential to a treatment planning system. A reconstruction framework based on image segmentation is presented. The framework extracts isosurface of organs or tissues by means of Marching Cubes. Marching Cubes is implemented and its ambiguities is solved by asymptotic decider. Marching Cubes can get an approximation to the isosurface. The approximation is composed by huge number of triangle trips. To render and interact in real time, a method of mesh simplification is presented, which can reduce the number of triangles composing the isosurface while preserving the precision and topological correctness of the original geometry model.There are several variable parameters in a dynamical focused Gamma knife treatment planning system. An optimized treatment procedure is presented in the paper. This optimized treatment procedure reduces the number of variable parameters and simplifies treatment planning. Inverse planning can decrease the treatment time as well as the dependence onplanner's experience. Automated treatment planning is the main aspect of inverse planning. A sphere packing method is presented to carry out automated treatment planning. It has the maximization of the volume in target field covered by spheres as the optimization target.At last, we have developed the CESC Treatment Planning System. The system has functionalities such as medical image processing, 3D reconstruction, target collocation and plan evaluating. It provides methods that physicians can manually collocate shots in three-dimensional space or that shots can be collocated automatically by a computer, and an approach that visualizes the dose field, which enable people monitor dose distribution by means of iso-dose-lines and iso-dose-surfaces. CESC Treatment Planning System has a reasonable system framework and optimized process, and it can satisfy the practical need in clinical applications in using dynamical focused Gamma knife treatment system.