This process uses a catheter that is placed inside the body, either directly into the tumor or near it. Radiation oncologists can place radioactive material in the catheter which delivers a high dose of radiation directly to the tumor. This helps to kill cancer cells and shrink tumors. Higher doses of radiation are given to treat a smaller area in less time than other types of treatments. This helps minimize damage to nearby tissues. This type of therapy is commonly used with cancers that are easy to reach. After treatments are completed, the catheter is removed.