Radiotherapy for seminomas should choose different irradiation sites according to different stages of seminomas. The most classic irradiation range for stage I patients is the para-abdominal aorta plus the ipsilateral iliac lymph node region; for stage IIA patients (retroperitoneal lymph nodes ≤ 5 cm), the irradiation range includes the para-abdominal aorta and the ipsilateral iliac lymph node region; for stage IIB patients (retroperitoneal lymph nodes ≤ 5 cm), the recommended irradiation field range, in addition to the para-abdominal aorta and the ipsilateral iliac lymph node region, should also include the metastatic lymph nodes around the 1.5 to 2.0 cm Boundary, such as superficial lymph nodes. 1. Retroperitoneal lymph nodes: Retroperitoneal lymph nodes are usually located in the lumbar region and on both sides of the spine. In severe cases of seminomas, they may metastasize via the peritoneal lymph nodes, resulting in enlarged peritoneal lymph nodes. 2. Bilateral inguinal lymph nodes: mainly located in the inguinal canal in front of the outer ring, when the spermatogonial tumor metastasizes through bilateral inguinal lymph nodes, it will lead to enlargement of local lymph nodes, and the tumor can be shrunk by radiotherapy. 3. Shallow lymph nodes: it refers to the relatively shallow lymph nodes in the body, such as cervical lymph nodes, axillary lymph nodes, etc. After localized metastasis, radiotherapy can be carried out to inhibit the growth of the cancer cells and reduce the size of the tumor. Radiotherapy for seminoma can irradiate the above parts, but it should be carried out according to the stage of seminoma, and it should be carried out under the guidance of clinicians.