| Objective:To study the relationship between the degree of colon injury andthe dose of the colon in the rabbits,which were irradiated by different doses of 125I seeds.Metheods:36 male New Zealand rabbits from the animal experiment center of Hebei Medical University,which were randomly divided into 4groups with random number table method;group A（100Gy）,group B（160Gy）,group C（200Gy）,group D（empty source group）.Each group included 9rabbits.The colon wall of rabbits from 4 groups were implanted group A0.5mCi,group B,0.8mCi,group C,1.0mCi and group D 0.0mCi 4 125I seeds respectively.4 125I seeds maked up a rectangle.Transverse spacing of two 125I seeds 1cm,longitudinal spacing of two 125I seeds 0.5cm.The New Zealand rabbits were placed on the CT scanning bed Immediately after implantation,and scanned for CT.Then the CT images were loaded into TPS.The colon wall which the particles were located was delineated as the target,with long2cm and wide 1cm,and the postoperative validation plan was carried out.Then absorption dose of 2cm2 rabbit colon wall was calculated in the A group,B group,group C,group D respectively.At the 60 days,120 days,180 days after implantation we willed kill the rabbits and get the specimen.The changes of general conditions of animals were observed every day.It was tested that the temperature,erythrocyte,hemoglobin,platelet,leukocyte at the preoperative and the 3 time points after implantation.When getting the specimen,we willed observed the changes of adhesion between colon and 125I seeds and gave a score according the animal model of Belluco standard.The wall of the colon with 4%neutral formalin fixed was observed by the senior pathologist in the light microscope after paraffin,paraffin sections,stained with HE,and evaluated damage degree of the colon wall.Results:1.General condition:The abdominal incision healed very well after implantation without wound bleeding,exudation,purulent infection and other complications,and normal diet,no clinical symptoms of anorexia,diarrhea.The weight of rabbits were increased equably at the time of killing animals.60days,120 days,180 days,The weight,temperature and blood cells including erythrocyte,hemoglobin,platelets were within the reference range after preoperative and postoperative,there were no significant differences between the 4 groups（P>0.05）.2.The general observation of colonic wall:In the group A,there was adhesion during the colon wall,abdominal wall and particle linear at 60 days,120 days,180 days.The adhesion area was 26%-50%.Adhesion is translucent,without vascular connective tissue,tenacious.We could separate the adhesion.Adhesion Belluco score:6±0.00 points.The adhesion Belluco score of B was same to group A at 60 days,120 days.,Adhesion Belluco score:6±0.00 points.At 180 days we could see the toughness of adhesion was strengthen,and sharped separation,Adhesion Belluco score:6.67±0.58 points.The adhesion score of group C is same to group A at 60 days,Adhesion Belluco score:6.67±0.58 points.At 120 days and180 days of group C,we could see the adhesion area was increased,but the adhesion area was less than 50%,Adhesion Belluco score:7.00±0.00 points.In group D,the adhesion area between colon wall and abdominal wall and particle linear was<25%at 60,120 and 180 days.The adhesion was membrane,transparent and wire like connective tissue.Adhesion could be traced and separated,Adhesion Belluco score:4.00±0.00 points.3.Histopathological observation:Colonic pathological injury score,In the group A,60 days,120 days were 1 score,the colonic pathological injury score of 180 days was 2;60 days in group B,colonic pathological injury score was 1points.The colonic pathological injury score was 2 at 120 days,180 days;60days in group C colonic pathological injury score was 2,120 days,180 days of colon injury reason score was 3;In D group,the colonic pathological injury score was 0 at 60 days,120 days,180 days was respectively.Conclusions:1.Radioactive 125I seeds could cause the normal rabbit colon damage,which was increased with dose of 125I seed increased.2.The 2cm2 experimental rabbit colon received 200Gy of radioactive 125I seed irradiation could cause a severe pathological damage of colonic mucosal in 180 days,and received 160Gy of radioactive 125I seeds irradiation pathological damage was minor.3.When radioactive 125I seeds are implanted in the treatment of tumors,it is recommended that the radiation dose of 2cm2 colon wall is less than160Gy. |
