Iodine 125 radioactive particle implantation is a kind of internal irradiation radiotherapy by implanting radioactive particles into the tumor through the method of puncture. With the further development of interventional technology, the clinical application of particle implantation therapy has been increasing in recent years, but it is necessary to grasp its indications. Of course, there are many patients who choose traditional external irradiation in the clinic, so what is the difference between the two? 1, external irradiation is a non-invasive operation, and the operation technique is quite simple; while iodine 125 particle implantation is an invasive operation, and the surgical technique is relatively more complicated. 2. External irradiation is larger in scope and the dose is relatively low, while iodine 125 particle implantation is smaller in scope and the dose is relatively high, which can reach 2-3 times of external radiotherapy. In terms of efficacy, the local control rate of iodine 125 particle implantation is higher, and many patients with residual lesions or recurrence after external radiotherapy can be treated with additional particles, the control range of which depends on the scope of particle implantation. 4. In terms of side effects, iodine 125 particle implantation has a smaller impact on the human body than external radiation, with fewer side effects and a lower chance of radiation pneumonia. 5. In terms of treatment time, iodine 125 particle implantation is a single implantation, and the effective duration of irradiation is 6 months, while external irradiation is usually once a day, 5 times a week, and the general treatment lasts 1-2 months. In terms of reliability, iodine 125 particle implantation depends more on the surgeon’s surgical level, while external irradiation depends on the machine and the doctor’s daily positioning. 7. Economically speaking, the smaller the tumor, the better the effect of iodine 125 particle implantation and the lower the cost. 8. Indications: lung tumors, metastatic lymph nodes, liver metastases, adrenal metastases, gynecological tumor recurrence after surgery, etc.