The Optimization Of Enhancement Scanning Delay With CT-based Simulation Before Cyberknife Treatment Of Pancreatic Cancer

Part I Study of the optimal delay time of scan on enhancement with CT-based simulation before cyberknife treatment of pancreatic cancerObjective: To explore the optimal delay time of enhanced scanning with CT-based simulation before cyberknife treatment of pancreatic cancer and to analyze the correlations between the target delineation and the rating items.Methods: One hundred and twenty pancreatic cancer patients underwent Philips 16 large aperture spiral CT before cyberknife treatment.Patients were assigned to three groups with scan delays of 25,45,and 65 seconds(group A);30,50,and 70 seconds(group B);and 35,55,and 75 seconds(group C)respectively.After the scans were completed,images were evaluated by three associate professors of radiation oncology.The items rating in different time points were compared using a random intercept model of mathematical mean in three groups of patients.Then the items rating of different time points were compared in pairs using the Sidak method.One-way ANOVA was used to compare the optimal time point of each group,so the optimal delay time of enhanced scanning with CT-based simulation before cyberknife treatment of pancreatic cancer was obtained.Pearson method was used to analyze the correlations between the target delineation and the rating items.Results: The CT enhanced scanning in the intra-group comparison of rating items,the tumor boundaries,retroperitoneal lymph nodes,duodenal images,accuracy of target volume delineations in 45 s and 65 s,50s and 70 s,55s and 75 s items rating difference were not statistically significant,but significantly superior than those of 25 s,30s,35 s respectively(P < 0.0001).Considering the precise radiotherapy mainly depending on the accuracy of target delineation,the optimal time was obtained respectively for 65 s,50s,and 55 s.Because there was no significant difference in the tumor boundaries and retroperitoneal lymph nodes,duodenum and target delineations etc.rating items in above mentioned time had no significant statistical difference(P > 0.05).Therefore,the proposed delay time interval was 50s-65 s,and in 55 s the average value of the target volume delineation was the highest.When the scan delay time was 55 s,the certain correlation with the reflect of tumor boundaries,duodenum,retroperitoneal lymph nodes and requirement of other images or not could be found.Meanwhile,the target delineation was positively correlated with the tumor boundary(r=0.9144,P < 0.0001),and negatively correlated with requirement of other images or not(r=-0.9263,P < 0.0001),but with few correlation with peripancreatic vessels(P > 0.05).Conclusion: The recommended delay time interval of pancreatic cancer before cyberknife treatment CT enhanced scanning was 50s-65 s,and the optimal time point was 55 s.The target volume delineation was positively correlated with the boundary of the tumor,and showed significant negative correlation with requirement of other images or not.Part II Study of the optimization of CT location and enhanced scanning time before treatment of carcinoma in different positions of pancreasObjective: To explore the optimal scan delay time of enhanced scanning with CT-based simulation before treatment of carcinoma in different positions of the pancreas.Materials and Methods: Fifty-three patients with carcinoma of the head of the pancreas and 60 pancreatic cancer patients in the body or tail underwent Philips 16 large aperture spiral CT before cyberknife treatment.Patients were assigned to three groups with scan delays of 25,45,and 65 seconds(group A,pancreatic head 18,pancreatic body or tail 21);30,50,and 70 seconds(group B,pancreatic head 17,pancreatic body or tail 19);and 35,55,and 75 seconds(group C,pancreatic head 18,pancreatic body or tail 20)respectively.After the scans were completed,images were evaluated by three associate professors of radiation oncology.The items rating in different time points were compared using a random intercept model of mathematical mean in three groups of patients.Then the items rating of different time points were compared in pairs using the Sidak method.One-way ANOVA was used to compare the optimal time point of each group,so the optimal delay time of enhanced scanning with CT-based simulation before cyberknife treatment of pancreatic cancer was obtained.Results: The tumor in the pancreatic head and the pancreatic body or tail in CT enhanced scanning in three groups of target delineation with the highest scores of the delayed time points were 45s/65 s,50s/50 s,55s/75 s respectively.There was no significant difference in the rates of 55 s,50s and 45 s of the tumor in the pancreatic head.Similarly,no significant difference could be found in the rates of 65 s,50s and 75 s of the tumor in the pancreatic body and tail.Conclusion:The recommended delay time interval of patients with the tumor in pancreatic head with CT enhanced scanning was 50s-65 s,and 50s-75 s of the tumor in the pancreatic body or tail.