IMRT and Timing in Combination With EGFRTKI for Stage IV Non-small-cell Lung Cancer

This study is for patients with EFGR gene sensitive mutations diagnosed by pathology or cytology, having a course of chest radiotherapy treatment and molecular Target Therapy for the treatment of stage IV non-small cell lung cancer. Patients with non-small cell lung cancer have a risk of the tumour in the lung recurring or progressing after treatment. In this study, the investigators aim to verify the following hypothesis: * whether in combination with concurrent or concomitant EGFR-TKI regimen chemotherapy, Intensity Modulated Radiation Therapy can reduce the risk of the tumour in the lung recurring or progressing similarily. * Intensity Modulated Radiation Therapy concomitant with EGFR-TKI has a better normal tissue dose/volume tolerance than concurrent regimen. * the survival can be improved by using this new molecular Target-radiotherapy method.