External radiation therapy for cholangiocarcinoma: There are various forms of external radiation therapy, usually using 60 cobalt or linear gas pedal, according to the positioning of CT examination, 3 to 4 fields of irradiation are used to irradiate outside the body at 2.0Gy per day, the total amount of 45-60Gy. The radiation damage to the above organs should be minimized. If radiotherapy is given after surgery, metal markers should be placed at the time of surgery to indicate the irradiation field for more accurate localization, which can narrow the radiotherapy area and reduce side injuries. For patients with metal internal support ducts already placed in the biliary tract, anterior-posterior counter-irradiation is more effective, but the irradiation should extend beyond the stent because the ends of the stent are often blocked by growing tumors. There are reports that external irradiation with 60 cobalt can achieve significant results in 50% of patients, including pain relief, jaundice reduction or tumor shrinkage, etc. It is especially effective for those with cancer cells remaining in the bile duct stump after tumor resection, and can significantly prolong survival. There are also reports of treating cholangiocarcinoma with stereotactic X-ray irradiation. The CT scan is positioned and a three-dimensional plan is made, and the CTV (clinical tumor volume) and PTV (planned tumor volume) are marked. Generally, 5-6 irradiation fields were laid out, 80%-90% isodose lines were wrapped around the PTV and normalized, and the irradiated tumor volume was 35 Gy for a total of 7 irradiations in 14 days, or the tumor volume was 36 Gy for a total of 6 irradiations in 12 days. Observations showed tumor shrinkage and good effect on reducing jaundice and other symptoms.In 1997, Pederson et al. reported in vitro and animal experiments on the killing effect of molecular chemotherapy + radiotherapy sensitization on bile duct cancer cells. The approach was to construct a toxin gene/precursor complex using molecular biology to convert 5-FU precursor 5-fluorocytosine into 5-FU intracellularly to enhance the intracellular toxic effect of 5-FU and achieve massive killing of bile duct cancer cells. The radiosensitizing effect of 5-FU was also utilized, followed by 60 cobalt radiotherapy. Significant results have been reported, and this molecular chemotherapy+radiotherapy approach with toxin genes/precursors may become a new strategy for the comprehensive treatment of cholangiocarcinoma. Acute side effects are usually not very serious, such as nausea and duodenitis, but sometimes cholangitis and biliary bleeding can occur and require prompt treatment. The later stage mainly includes duodenal injury and biliary stricture. Intraluminal radiation therapy for bile duct cancer: The advantage is that it can irradiate the lesion at high dose locally with little damage to the surrounding normal tissues. Internal radiation therapy is usually administered through PTCD or ERCP, or through surgically placed T-tube or U-tube with radiation source 192Ir placed near the bile duct tumor, generally 7-8Gy/time, once every 5-7 days, 4 times, total 28-36Gy. The drainage tube is led directly from the exploratory incision of the common bile duct, so that the angle between the common bile duct and the supporting drainage tube is >120°, which facilitates the entry of the radiation source into the bile duct to the cancer, and can be carried out after 2 weeks of postoperative stabilization. Good results have been reported, and even in some cases the tumor disappeared after fiberoptic cholangioscopy after 2 to 3 irradiations after surgery.