Research On Target Definition In The Radiotherapy Based On The Image Fusion

Malignant tumor is threatening human health badly. As one of three main treatment methods, radiotherapy has been attached more and more importance. And it has been developed rapidly. For radiotherapy, the key problem is how to definite a tumor's location and area accurately. Now, the main imaging devices we used to definite the target area in radiotherapy are CT, MRI et al that mainly provide the anatomy images. While the imaging devices such as PET, SPECT, MRS can reflect some biological information in tumor. They can help us to find the oiable cells area, hypoxic cells area and proliferation cells area et al inside tumor. We called the areas that containing those cells as "biological target volume". We can give these different biological cells different dose by intensity modulated radiation therapy (IMRT) method. This can kill more tumor cells and increase tumor control rate.The precision of the target volume's definition have a strong influence on tumor control rate. In order to improve the precision of target volume's definition, we use fused image, which is acquired by mixing the anatomy image and functional image in a single image, to definite the target volume. To improve the location precision in fusion-image, we developed a stereotactic body frame system, which can provide 3D coordinate value in different images. A set of criterions has also been developed to check the system's location precision. Then an interface program based on DICOM3.0 protocol has been developed to extract images from different imaging devices. Finally, 4 skilled doctors have been invited to get their definition of three typical tumors' target volume based on CT images and fused images respectively. A comparison has been made between these definitions.The experimental results show that the stereotactic body frame system's location errors in CT image are less than 1mm, and the errors in MRI image are less than 1.73mm. With the use of stereotactic body frame system, the location error in fused image can be decreased from 3-4mm to 2-3mm. The comparison on definition of target volume shows that based on CT images, there is some difference on 10 definitions same doctor have made on...