Abstract: The technology of PET had developed rapidly, and made it more and more important in stage and radiotherapy of tumor. The results of PET can give some biological information, such as the density of tumor and the sensitiveness to radiotherapy, these information together with the morphologic modalities, for example CT and MRI, offer a new opportunity to target the tumor cell in the therapy. Intensive Modulated Radiotherapy based on PET-CT, have the ability to display the biologic target through the fusion image of PET and CT, and create the concept of biologic target volume. In theory, within the high metabolic region of fluorideoxyglucose, you can apply a higher appropriate daily radiotherapy dose for better result. So the tumor diagnostic technology of PET-CT and IMRT bring a new biologic radiotherapy into reality.