A Dosimetric Comparison On Three-Dimensional Conformal Radiotherapy(3D-CRT) And Intensity Modulated Radiotherapy(IMRT) In The Treatment Of Pancreatic Carcinoma

Background:Malignant diseases currently occupy the first cause of death in our country, our country has become a very important public health problem. Including the ‘King of cancer’said pancreatic cancer’s incidence and mortality rates are rising year by year due to difficulties in early diagnosis of pancreatic cancer, poor treatment, which seriously affecting the quality of life of patients. As one of the three treatment of malignant tumors, radiation therapy in the comprehensive treatment of malignant tumors occupy an important position, there are statistics show that radiation therapy treatment requires the participation of more than 70% of malignant tumors, especially in patients with locally advanced, the surgery has not much meaning, and radiation therapy as a topical treatment can be controlled to a certain extent of disease progression, relieve symptoms, improve quality of life and prolong survival. In recent years, with the progress and development of radiation therapy technology, particularly to carry out and application of three-dimensional conformal radiotherapy and intensity modulated radiotherapy techniques for radiation treatment of cancer has risen to a new height. Studies have shown that three-dimensional conformal radiation therapy has a very prominent advantages compared to IMRT, of which the most prominent feature is the ability to give a target with different dose distributions and dose gradient at the edge of the treatment target to reduce very quickly, this can achieve a high dose limiting in the target area to be irradiated, the irradiation dose greatest degree of tumor volume, while the radiation dose to normal tissue around the tumor target to a minimum, while in IMRT, which target dose uniformity and conformal clinical target volume are better, which is treatment of the disease also has certain advantages. Currently on the application of clinical and experimental research in pancreatic cancer, IMRT radiotherapy are not many, but IMRT improve target dose and reduce side effects of radiotherapy have an advantage on the whole display, which requires a large number of controlled clinical studies to further confirm the IMRT pancreatic Cancer advantage. In view of this, we conducted a dosimetric comparison on Three-Dimensional conformal Radiotherapy and Intensity Modulated Radiotherapy in the treatment of pancreatic carcinoma.Objective:To confirm appropriate treatment method for pancreatic carcinoma patients through comparing and analyzing a dosimetric comparison on Three Dimensional conformal Radiotherapy( 3D-CRT) plan and Intensity Modulated Radiotherapy(IMRT) plan. Methods:Retrospective analysis from February 2013 to June 2015 in our hospital during radiotherapy and 10 patients with pancreatic cancer for the study, and according to the same CT simulation images using Varian Eclipse planning system, respectively, in each case patients with design 3D-CRT and IMRT plan. Among prescription dose planning target volume are: 2Gy/times/day, a total of 60Gy/30 F. In order to reduce the impact of 3D-CRT plans to bring the number of different radiation field are designed to be the center of the irradiation five fields and require 3D-CRT plans 100% isodose surrounding the 90% of the PTV, IMRT plan 100% isodose curves surrounding the 95% of PTV. Weight depending on the circumstances configured by the physical division of the small intestine V40 <65%, spinal cord Dmax <40Gy, kidney V20 <20%, stomach V30 <30%, optimization of power: according to RTOG standard dose limiting organs at risk. After the program is completed by SAS9.4 comparing the two programs target evenness and organs at risk(liver, kidney, small intestine, stomach, spinal cord) to determine the difference in dose distribution is more suitable for radiation therapy of pancreatic cancer. Results:1.Intensity Modulated Radiation Therapy(IMRT) plan’s and three-dimensional conformal radiation therapy(3D-CRT) plan’s(five fields) dose uniformity has no significant difference.2. To compared three-dimensional conformal radiation therapy(3D-CRT) plan(five fields),Intensity Modulated Radiation Therapy(IMRT) plan can improve the volume of high-dose clinical target.3. To compared three-dimensional conformal radiation therapy(3D-CRT) plan(five fields),Intensity Modulated Radiation Therapy(IMRT) plan ’s organs at risk in kidney and small intestine by high-dose of low volume illuminated, in liver and stomach by low-dose of low volume illuminated, and the others radiation dose have no significant difference. Conclusion:To compared with three-dimensional conformal radiation therapy(3D-CRT) plan,Intensity Modulated Radiation Therapy(IMRT) plan has advantage on dosimetry.