The Early Radiation Injury Induced By The Iodine-125 Brachytherapy To The Bile Duct In Rabbits

Hepatoduodenal ligament lymph nodes is a common gastrointestinal cancer lymph node metastatic sites, Some studies said hepatoduodenal ligament lymph node metastasis rate was 95.45% in the intrahepatic bile duct cancer;It was reported that the hepatoduodenal ligament lymph node metastasis rate was 15.2 -20% in distal stomach cancer;when if gastric serosa involved the rate was up to 22-24%.Metastatic carcinoma cause jaundice, duodenal obstruction that seriously affect the quality of life and prognosis of patients, lead to patient mortality. The special anatomical lymph node adjacent to important organs such as the bile duct, portal vein, hepatic artery, is not easy to be resected; chemotherapy is not sensitive; high-dose external beam radiation therapy may prolong the survival period, but because of the dose restrictions of liver, kidney and gastrointestinal tract and other sensitive organ, the desired dose is difficult to achieve, clinical treatment is more difficult.125I seed implantation in malignant tumor had a long history and developed quickly in recent decade and become the example of the best conformal radiotherapy. Interstitial implantation of radioactive seeds, is a good method which can greatly injury tumor cells in different time of cell cycle by implanting radioactive microsources which can irradiate garmmer rays with low energy continuously whereas normal tissue is not or slightly injuried. It has a small pathological damage, which limited the scope of 5mm away from the seeds. The energy attenuation is inversely proportional to the distance square. To adjust the space and activity of particle source, can achieve a high degree of fitness-type, which can multiplied improve tumor target dose. 125I seed implantation technology has been quite a broad range of applications in abroad: especially in the treatment of prostate cancer, 125I seed implantation had become the first choice for early prostate cancer. With the inter-organizational 125I seed implantation radiotherapy in cancer therapy applications, its security is received more attention. Rectal complications occurred after 125I seed implantation, in the prostate cancer, manifested as increased frequency of bowel movements accompanied by tenesmus , mucoid stools, blood stools, severe or even urinary rectal fistula. It is national reported that abdominal complications rate was 14.0% after 125I implantation of rectal cancer. However, it is little reported that application of lymph node metastasis and complications after implantation.Duodenal ligament lymph nodes adjacent the bile duct, whether inflict radiation damage after particles implantation is certain. For which we observated bile duct injury in different time though experiment with different doses of radioactive 125I seed implantation. To solve some more critical problems on safety, earlier radioactive damage and clinical effect of bile duct tissue with interstitial implantation of 125I seeds, provided basis for experiments and dosimetry to prevente and treat hepatoduodenal ligament lymph node metastasis .Objective:To investigate early radiation injury the in normal bile duct of rabbits in different time receiving different dose 125I brachytherapy.Methods: 48 normal rabbits, according to computer-generated random numbers were randomly divided into four groups: control group, treated A group (80 Gy), B group (120 Gy), C group (160Gy).Conventional surgery 3 particles 125I were implantated like a triangle in the of bile duct sheath of treated group , space is 0.3- 0.5cm, while an empty source of particles implanted in the control group. Compare general situation,weight change, complications, white blood cell counts, seeds'losing-rate after 30,60d of thetreated group and the control group. Observate pathological and ultrastructure changes of bile duct 0.5cm away from source by light microscopy and transmission electron microscopy.Results:The survival rate of rabbits is 100%.The seeds'losing-rate was 5.56%(2/36)in control group,and 4.63%(5/108)in treated group.The organ and tissue arounding the implaned bile ductt have no radiation damage. There is not fistula, perforation, hemorrhage, death and other serious complications of bile duct. The parts of particle adhesion with surrounding tissues in the treated group and the control group. The weight of rabbits before implantion were 2195.67±139.11 g,2277.67±143.37g, 2280.42±184.99g, 2240.83±116.90g,and all lessen after operation and increased gradually with drink and food recovering.There was no significant difference between control and treated groups at the same time(P>0.05). In same group, only7d vs 0d had no significant difference(P>0.05),others had significant difference(P<0.05). WBC count determination results only 7d vs 0d had significant difference(P<0.05) others had no significant difference(P>0.05) in the same gourp, There was no significant difference between control and treated groups at the same time(P>0.05). Light microscopy results: In the control group, there was only slight inflammatory changes.It was no significant change with time extension. The structure of bile duct was normal. 30d, when 80Gy group bile duct epithelial partly detached Villi became short or irregularly arranged; 120Gy group focal epithelial shedd, hair lost, small blood vessels in the submucosa shows hyperemia, edema. 160Gy Group bile duct epithelium extensively flake off , accompanied by focal necrosis and bleeding. 60d extent of injury in each group increased when compared with 30d, but the injuries were not involving the muscular layer. schmidt pathology score 0 points in the control group. 30d A group 1.17±0.26 points, B group 3.33±0.41 points, C group 5.17±0.26; 60d A group 2.42±0.38 points, B group 4.17±0.26 min, C group 6.08±0.26 points, injuries are only a limited in the mucous layer. In same group,there was significant difference of different time(P<0.05), There was significant difference between control and treated groups at the same time(P<0.05). SEM Results: In control group ,there was no significant change; 30d ,80Gy group some mitochondrial cristae and membrane fusion, edema , the endoplasmic reticulum.slightly expansed and microvilli became short. 120Gy group mitochondrial clearly swell, vacuolization and the medullary occurred ,dilated endoplasmic reticulum, there was finger cross. 160Gy occurred ,dilated endoplasmic reticulum, there was finger cross. 160Gy group ,cell membrane damaged, cytoplasmic spillovered , mucosal layer of epithelial cells shed. 60d ,the extent of injury in each group increased compared with 30d.Conclusion:The radiation damage was minor when 80Gy-160Gy 125I particles were implanted in bile duct. there was not bile leakage, perforation of early irreversible damage. with extension of time,the dose increased,damage depth and scope of injury was not increase.