Cone-beam Ct In The Accurate Radiation Therapy For Lung Tumors In Applied Research

To study the motion bound of the Gross Target Volume (GTV) of lung tumor, under the help of cone beam CT(CBCT), attaining the fusion of CBCT images and CT images, by using image match arithmetic, which could show the motion displacement of GTV in three directions(X, Y and Z axes). That could confirm the margin of the GTV in a 3D conformal Radiotherapy (3DCRT) Planning, and make a personal RT planning, which could be also assured by CBCT.With the model based on the rigid body translation and rotation, accomplishing the registration, by maximizing the mutual information of CT and CBCT images. Searching optimum translation and rotation parameters with Powell arithmetic, confirming optimum step size in search in each dimensions with Brent arithmetic, plus the registration of CT and CBCT images which using multi-resolution search in strategy. It is proved that, by the method above, the mutual information, can accomplish the registration of multi-modality medical image accurately, fleetly, and real-time.It could better guide to confirm the margin from GTV to the Planning Target Volume (PTV), by applying the method above to the research of tumor motion displacement in active breathing state.There are significant differences in motion displacements between Z-axis and X and Y-axes.The method above can also be applied to the research of NSCLC radiotherapy. By adjusting the margin of GTV, reducing the dose distribution to the normal lung tissue, V₂₀, D_mean and max dose of spinal cord, the lesions caused by radiation could be effectively reduced. Furthermore, the lethiferous dose to the tumor could be increased.Image Guided Radiotherapy is a newly study, mixed by several studies knowledges, due to applications on radiotherapy of imaging equipments and technologies. On-line Volume Imaging technology, such as CBCT, could be used in confirming and tracing GTV in several ways, and guiding radiotherapy, which make IGRT more accurate. IGRT could not only destroy tumor tissue, but reduce normal tissue radiation lesion. No matter the shape and motion displacement of GTV, IGRT could assure the dose on GTV. In one word, IGRT is a technique to assure the Intensity Modulated Radiotherapy (IMRT).