Cervical cancer is the first tumor that can be treated with “precision radiotherapy” There is a distinction between “internal radiotherapy” and “external radiotherapy” for cervical cancer, also known as “intracavitary radiotherapy” and “external radiotherapy”, or “brachytherapy” and “teletherapy”. There are two types of cervical cancer tumors that can be treated with “internal radiotherapy” and “external radiotherapy”, also called “intracavitary radiotherapy” and “external radiotherapy”, or “brachytherapy” and “distant radiotherapy”. ”External radiotherapy” is what people usually understand, lying on the bed and irradiating through the belly. Internal radiotherapy” is to place the radioactive material inside the body and irradiate the tumor directly. Internal radiotherapy can be done for cervical cancer because of the existence of a natural cavity, the vagina, that is connected to the outside world. The doctor can first place a special device inside the patient’s vagina, and then the radioactive source enters the device and acts directly on the cervical tumor. Today, there are many new terms about radiotherapy, such as precision radiotherapy, intensity-modulated radiotherapy, etc. How do I choose between in vivo and external radiation therapy? External body radiation can take into account the whole pelvis, taking into account the uterus, lymph nodes, parametrium lesions, etc. There is a concept that the efficacy is inversely proportional to the square of the distance. That is, the closer the distance, the better the effect; the farther the distance, the faster the effectiveness decreases. There are early and late stages of cervical cancer. In early stage, local tumor is the main focus and the lesions are small and limited, so radiotherapy should be mainly in vivo and in vitro, and irradiation against the tumor can cure it. In advanced stage, the tumor has already exceeded the cervix and involved the parametrium or lower vagina, and the lesions are very extensive. At this time, radiotherapy should be mainly outside the body and supplemented inside the body. When facing outpatients, I will call external radiotherapy “small light”, internal radiotherapy “big light”, and intravaginal radiotherapy “medium light”, which is better understood and accepted by the general public. Internal radiotherapy has a variety of internal loading devices Internal radiotherapy is a general term, including a variety of ways to achieve. It varies according to the loading device of the radiation source into the body. In some cases, the radiation source is placed in a ball and then placed in the vagina. This is called a vaginal ball. Some place the radiation source in a tube that goes into the uterine cavity, called a cervical tube. Some can also radiate through the vaginal membrane. There is also a type of internal radiation called “tissue insertion,” which involves inserting a radioactive source with a needle-like jacket directly into the tumor and irradiating it.