Parameter Optimization And Template Establishment Of Intensity-modulated Radiotherapy Plan In Cervical And Upper Thoracic Esophageal Cancer

Objective: Based on Monaco plan system, this assay is about the research of IMRT treatment to cervical and upper thoracic Esophageal cancer. There is a better cure discovery of IMRT plan template optimization based on Monaco plan system by comparing and analyzing the indexes of tumor target area、risk organs and normal tissue when verifying the shoot segment number and making out different IMRT plan, and with analysis of the parameters of the smallest chosen segment coverage, continuous verification of the smallest segment coverage difference, small MU segment and the least distance between segments leaf surface.Methods: Eleven esophageal cancer patients in the radiotherapy department of Affiliated hospital of North Sichuan Medical College were selected in the research.Under specified conditions, all the patients underwent CT simulation.The image conveyed to the physics room for target delineation and drew up a plan.All of the target volumes were modified and confirmed by the physician of vicesenior title and senior title.Physicists set the Optimization parameters and changed the number of radiation field to establish different IMRT plan(A total of 44 plans), and then,they analysis the data about tumor target volume、organs at risk and normal tissue of different plans,finally got better radiotherapy plan.Results:The three fields was significantly lower than the other fields radiotherapy plan in V95% of PTV1 volume parameters(P<0.05), and the dose parameters in each IMRT plan had no significant difference(P>0.05).The volume parameters and dose parameters of PTV2 in each IMRT plan had no significant difference(P>0.05).Organs at risk:Thyroid gland, trachea and spinal cord in different irradiation fields plan had no significant difference. But V10、V20、V30 of the lung’s irradiated volume was the largest in three fields plan,however the five、seven and nine fields plan was smaller(P<0.05).Among the IMRT plan,the nine fields plan’s therapy time was the longest and the effect of treatment was the lowest(P>0.05).Patient(undefined normal tissue: CT scanning coverage exclusing the radiation volume and the tissue behind the organs at risk.) V20、V30、V40、V50, the volume of three irradiation fields plan was larger than the other irradiation fields plan(P<0.05), there is no significant difference between the plan at V5、V10、V60.Conclusion: The research uesd Elekta Monaco 3.2 IMRT radiotherapy planning system.we selected the size of 4.000cm2 as minimum field,area of 3.000cm2 as the minimum change,0.60 cm as the minimum width of leaf,6MU as the the minimum hop number.Under these limit conditions of radiotherapy plan,we found 5 fields and 7 fields plans were more suitable than the others in cervical and upper thoracic esophageal cancer.