For patients with lung malignancy, lung cancer or lung metastasis that cannot be removed by surgery, systemic or local radiotherapy is still performed to control the further development of the lesion, prolong the patient’s survival and improve the patient’s quality of life. The following is a successful case of “particle knife” application for advanced lung cancer in our department. The patient was a 68-year-old male smoker for 30+ years, with an average of 30 cigarettes per day, who was in good health in the past. The chest CT showed that a mass of about 125px in size, irregular in shape and lobulated, invaded the anterior chest wall and destroyed the bone of the left second anterior rib. The possibility of malignant lung tumor with bone metastasis was considered. Subsequently, a lung puncture biopsy was performed to confirm that it was squamous cell carcinoma. After consultation with the thoracic surgery department and communication with the family, the patient and the family chose the treatment plan of minimally invasive “particle knife” for the tumor, and “CT-guided iodine 125 particle implantation for left lung occupancy” was performed under local anesthesia at the end of May. He was discharged from the hospital at the end of May with no significant postoperative complications such as pneumothorax and hematoma, and was treated with anti-infection and pain relief before and after surgery. Image description (a): The above is the patient’s preoperative CT: a 125px occupancy in the anterior segment of the upper lobe of the left lung. Image caption (b): The above is the postoperative CT of the patient: the “particle knife” iodine 125 particles were evenly distributed in the lung lesion, but due to the risk of puncture and the limitation of the puncture site, some of the lesions were not distributed with the “particle knife”. Image caption (c): The above is the patient’s 2 month postoperative follow-up follow-up enhanced CT: the lung lesions are smaller compared to the preoperative lesions. Image caption (d): The above patient is seen on follow-up CT 4 months after surgery: the lung lesion is smaller compared with the preoperative lesion and two months after surgery, and the mass is shrinking toward the upper lobe of the left lung. Experience summary: For malignant tumor lesions that cannot be treated surgically or have little surgical significance, local radiotherapy using “particle knife” can control further damage to tissues and organs by primary lesions or metastases to a certain extent, prolong patients’ survival and improve their quality of life, but it cannot completely eliminate the tumor lesions or control the metastases to other areas. However, it cannot completely eliminate the tumor lesions or control the metastasis to other parts of the body.