腮腺放射,动物模型 z-bo 2020-08-05 635

　　Radiotherapy is one of the main treatment methods for head and neck tumors. Radiation injury of salivary glands is one of the common complications after radiotherapy for malignant tumors of the head and neck. The salivary gland tissue receives ionizing radiation, which leads to a decrease in secretory function, a significant decrease in saliva, dry mouth, difficulty in speech and swallowing, and decreased sense of taste. At the same time, the pH of saliva decreases and the viscosity increases to increase the incidence of dental caries and oral mucositis, and even cause stomach discomfort or gastric disease, affecting the health and quality of life of patients. In order to reduce the damage to the salivary glands caused by radiotherapy, people have adopted measures such as improved protection techniques, three-dimensional conformal treatment plans, and oral protective agents during radiotherapy, but these can only partially reduce the damage to the salivary glands. It is currently believed that the salivary glands in the head and neck organs, especially the parotid glands, are extremely sensitive to radiation. Therefore, studying the mechanism of radiation damage to the parotid glands is helpful to the prevention and treatment of radiation injuries.

　　Some scholars used Wuzhishan miniature pigs to establish a model of parotid gland radiation injury. The experiment selected 18 8-month-old miniature pigs, male, weighing 30-40kg. The animals were randomly divided into 15 Gy (7 heads) and 20 Gy (7 heads) ion beam radiation groups and a control group (4 heads). After conventional anesthesia of the miniature pigs, the parotid duct was retrogradely injected with 4ml of 40% diatrizoate meglumine for CT tomography, and the 3-DTP (3-dimensional treatment planning) system was used to design the radiation treatment plan. The target volume is the parotid gland on one side of the miniature pig, and calculation by single back field irradiation shows that 90% of the radiation dose covers one parotid gland. The radiation field is 12cm×10cm, the irradiation distance is 95cm from the skin, and the skin range of each animal is drawn. The radiation source uses a linear accelerator with an average energy of 6mV and a dose rate of 3.2 Gy/min. All dose calculations take the center of the parotid gland as the reference point, and the parotid glands of the 15Gy and 20Gy ion beam radiation groups are given a single radiation dose of 15Gy and 20Gy. In the 15Cy and 20Gy ion beam radiation groups, 2 animals were randomly selected and sacrificed 4 weeks after irradiation, and the other 5 animals were fed to 16 weeks and sacrificed. The 4 animals in the control group were treated the same as the experimental group except that they were not irradiated.

　　The experimental results show: ① Saliva flow rate: Before radiotherapy, there was no significant difference in saliva flow rate between the radiation group and the control group. After 4 weeks of 15Gy irradiation, there was no change in saliva flow rate on the radiated side and the non-radiated side. At 16 weeks, the saliva flow rate of the parotid glands on the radiated side was reduced by 60% compared with that before radiation; the saliva flow rate on the non-radiated side was reduced by 17% compared with that before the radiation. After 4 weeks of 20Gy irradiation, the saliva flow rate on the radiation side was reduced by about 50% compared to before radiation. At 16 weeks, the salivary flow rate of the parotid gland was reduced by about 80% compared with that before radiation, and the salivary flow rate of the non-radiated side of the parotid gland was reduced by 45% compared with that before radiation. ②Parotid gland weight: Compared with the control group, the total weight of the parotid glands in the 15Gy and 20Gy groups decreased by more than 50% at 4 and 16 weeks. ③ Pathological changes: The glands in the control group showed clear structure and uniform density of serous secretory acini. The nucleus was deeply stained on the side of the basement membrane, with many translucent secretory vesicles and secretory ducts with normal structure. Glands with 15Gy and 20Gy radiation at 16 weeks showed a decrease in leaflet area, acinar volume and number, adipose tissue hyperplasia, and interstitial fibrosis, manifested as atrophy and degeneration of acinar cells, and at the same time, all the interstitial cells were visible. This kind of inflammatory cell infiltration, mainly monocytes and scattered lymphocytes, many ducts are swollen, there are cell debris and concentrated secretions in the ducts.