This study is for people with prostate cancer that has returned after surgery. It looks at using a special type of treatment called radioligand therapy with a drug named 177Lu-rhPSMA-10.1. This drug attaches to cancer cells and delivers radiation directly to them, helping to kill the cancer cells. Patients will also get another type of radiation treatment called external beam radiotherapy (EBRT), which uses x-rays to target cancer. The study will check how safe this treatment is, what the side effects are, and the best dose to use. Patients will receive the treatment through an IV (a needle in the vein) and have their blood tested. To join, you need to have had prostate surgery, be over 18, and have cancer in the pelvis area. However, you can't join if you have certain health problems, like severe kidney issues or other risks. The study will last until 6 weeks after the last treatment.

• Participants must be over 18 years old and have prostate cancer that has returned.
• The treatment includes special radiation therapy and a radioactive drug.
• Follow-up is needed 6 weeks after the last treatment session.