Research On Fast Dose Calculation Method Based On Pencil-beam Kernel

Radiation therapy is a local treatment method for malignant tumors,which is widely used in clinical medical treatment.Accurate and fast dose calculation is a necessary condition for the feasibility of a radiation therapy planning system.Aiming at the problem that the traditional pencil-beam kernels dose calculation process is complicated and the speed is slow,this subject proposes a fast dose calculation method that reduces the complexity of the algorithm,and GPU acceleration is performed on the more complex dose superimposed part of the method.The speed of dose calculation is accelerated when the calculation accuracy is basically the same.The main research contents are as follows:(1)A new method for dose calculation based on pencil-beam kernels.The traditional pencil-beam kernel dose calculation algorithm takes the energy deposition point as the center to calculate the dose distribution.A large amount of time is used to calculate the intersection between the energy kernel axis and voxels of different beams.The calculation process is complex and the speed is slow.Therefore,this paper proposes a new algorithm.In the spherical shell coordinate system,the similarity of the intersection between the axis and the voxel at the collision points of different spherical shell layers is used to calculate the dose distribution with the collision point as the center.Firstly,the phantom and energy spectrum information are used to obtain the parameters of the depth and lateral components of the pencil-beam kernel.At the same time,the intersection of each beam in the range of the initial spherical shell collision point with the voxel is calculated in advance.And use the ratio of the depth of the initial spherical shell layer to the depth of other spherical shell layers as a correction factor to obtain the intersection of the axis and the voxel at the collision point of other layers.Secondly,the dose distribution of different beams at the collision point iscalculated in the spherical shell coordinate system.The experimental results show that compared with the traditional pencil-beam kernels dose algorithm,the improved algorithm has greatly improved the calculation speed without changing the accuracy.(2)GPU accelerated new algorithm.In view of the current advantages of GPU parallel computing and its wide application in the field of science and medicine,based on the new algorithm proposed in this paper,GPU is used to accelerate the more complex parts of the algorithm.First,the matlab program is transformed into C language program,and the CUDA C was used to perform parallel operations on the equivalent depth of the beam entering the phantom and the loop of the dose superposition,which made the data processing faster and reduced the overall dose calculation time.The experimental results show that compared with the CPU program,the GPU can indeed increase the speed of dose calculation,and the acceleration ratio is more obvious when the amount of data is larger.At the same time,the accuracy of dose calculations has not decreased.Therefore,the GPU can be used to accelerate the dose calculation based on the pencil-beam kernel.