The incidence of radiation enteritis (RE) is dose dependent, with approximately 5% of patients experiencing RE at a radiation dose of 45 Gy and up to 50% at a dose of 65 Gy. The minimum tolerated dose is defined as 5% of patients receiving radiotherapy have clinical symptoms of significant radiation damage within 5 years, and the maximum tolerated dose is defined as 50% of patients have clinical symptoms. The radiation dose from the minimum to maximum tolerated dose in the gastrointestinal tract is 60-75 Gy in the esophagus, 45-65 Gy in the small intestine and colon, and 55-80 Gy in the rectum.
However, these doses are very close to the treatment doses for common abdominopelvic primary or secondary malignancies, such as the average doses for controlling cervical or endometrial cancer, ovarian cancer, and bladder cancer are 40-80, 40-50, and 40-60 Gy, respectively. Therefore, the safety range between the tumor cell killing dose and the maximum tolerated dose for normal tissues is very small, and it is very easy to cause damage to the normal tissues and flora of the intestine, leading to RE. leading to the occurrence of RE. In addition, the higher the splitting dose, the shorter the radiotherapy interval, the larger the radiation range, and the closer the radiation site is to the gastrointestinal tract, the higher the incidence of RE, and vice versa, the lower the incidence of RE.