The objective of this study is to evaluate the outcomes of radiofrequency ablation in the treatment of patients with malignant pulmonary nodules（not exceed 3cm ）who are not suitable candidates for or refuse surgical resection.

Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique widely used to treat solid tumors. Patients with malignant pulmonary nodules will undergo a series of CT- guided percutaneous RFA procedures. During the procedures，percutaneous needles will be inserted into the target tissues under CT guidance，the needles deliver thermal energy and then destroy the tumors by causing coagulation necrosis via tissue heating. The purpose of this study is to assess the effectiveness and safety of RFA in pulmonary nodules （maximum tumor diameter ≦30 mm） was 10 mm apart from the big trachea, primary bronchi, esophagus, great vessels，heart and pleura. Preoperative and postoperative evaluations，including recent laboratory tests evaluated and imaging studies reviewed，will be performed both before and after the procedures.

Inclusion Criteria:

1. Histologically confirmed malignant pulmonary nodules.
2. Patients refuse or are not suitable for surgical resections.
3. 1-3 pulmonary nodules , with a maximum tumor diameter ≦30 mm.
4. Minimum distance of nodules are at least 10 mm apart from the surrounding tissues as big trachea, primary bronchi, esophagus, great vessels，heart and pleura.

Exclusion Criteria:

1. Patients who has uncorrectable coagulation disorders, severe heart or pulmonary failure, or uncontrolled infections.
2. With extensive extrapulmonary or intrapulmonary metastasis.
3. Have taken anticoagulant as aspirin in one week.
4. Target nodules nearby pleura or other important hilum and mediastinum structures.
5. With metal implants are adjacent to the target tissues which will be covered with ablation area.