Radiotherapy is a medical treatment that uses high doses of radiation to kill or damage cancer cells. It can be delivered externally, using a machine called a linear accelerator, or internally, through a process known as brachytherapy, where radioactive sources are placed inside or near the tumor. This treatment aims to shrink tumors, prevent cancer from spreading, or relieve symptoms. Patients typically undergo several sessions of radiotherapy, depending on their specific condition and treatment plan. While it can be effective, it may also cause side effects, such as fatigue and skin irritation, which vary based on the area being treated and the radiation dose.