The main technical difficulties in radioactive iodine-125 seed implantation (RISI) lie in the complexity of operation and the control of operation quality. The current data shows that under the combined guidance of 3D-printing template and CT, the accuracy of RISI has been significantly improved, and the actual target dose could meet the design requirements of preoperative plan.

At present, 3D printing templates (3DPT) are divided into non-coplanar templates (3DPNCT) and coplanar templates (3DPCT). In clinical practice, due to the complex technical requirements, high production cost and long printing time of 3DPNCT, a considerable number of patients can also complete the treatment with 3DPCT. Moreover, compared with 3DPNCT, 3DPCT has the advantages of accurate needle path control, fast needle path adjustment, convenient for intraoperative real-time optimization, without waiting for printing time, easy for doctors to master, lower cost than 3DPNCT, and easy to carry out at the grass-roots level. Therefore, this study intends to explore 3DPCT technology to further clarify: (1) the accuracy of 3DPCT assisted CT guided RISI in the treatment of thoracic malignant tumors; (2) the short-term efficacy and toxicity of 3DPCT assisted CT guided RISI in the treatment of thoracic malignant tumors.

Inclusion Criteria:

• Pathological diagnosis of malignant tumor of chest, lesion diameter less than 7 cm.
• There is no extensive systemic metastasis or although there is metastasis, the metastasis have been controlled by early treatment.
• No bleeding tendency, anticoagulant therapy and / or antiplatelet coagulation drugs should be stopped for at least 1 week before treatment.
• No serious or uncontrolled underlying diseases (such as severe or uncontrolled hypertension, diabetes, cardiovascular and cerebrovascular diseases and organ dysfunction) are found.
• There is a suitable puncture path, and the therapeutic dose is expected to be achieved.
• KPS > 70, expected to tolerate puncture / seed implantation, and expected survival time greater than 3 months.

Exclusion Criteria:

• Severe impairment of lung function (such as FEV1 < 40% predicted value, FVC < 50% predicted value, DLCO < 40% predicted value).
• High risk of skin invasion and ulceration at the puncture site before treatment.
• There is a large range of liquefaction and necrosis in the lesion, and the expected seed distribution would be poor.
• Pregnant women, lactating women and mentally ill patients.
• The patient with poor compliance and unable to complete the treatment.
• Other conditions of the researchers who think it is not suitable to participate in this clinical trial.

De-identified individual participant data for all primary and secondary outcome measures will be made available.

Data will be available within 6 month after the study completion.

Data access requests will be reviewed by the research sponsor. Requestors will be required to sign a Data Access Agreement.