Interstitial irradiation therapy, also known as brachytherapy, is a method of cancer treatment that involves the insertion of radioactive sources into the tumor. However, there are several synonyms for interstitial irradiation therapy that are commonly used in medical literature. These include internal radiation therapy, implant radiation therapy, and seed implantation therapy. All of these terms refer to the same technique of inserting radioactive sources into the body to treat cancer. Interstitial irradiation therapy is an effective treatment option for many types of cancer, including prostate, breast, and gynecological cancers. It is often used in combination with other cancer treatments to maximize results.