Dosimetry Study Of Volumetric Modulated Arc Therapy For Esophageal Neoplasm

Part 1 Dosimetry study of volumetric modulated arc therapy and static intensity modulate radiotherapy for esophageal neoplasmObjective A feasibility study was performed to evaluate volumetric modulated arc therapy(VMAT)on advanced esophageal neoplasm against static intensity-modulate radiotherapy(s IMRT).Methods Thirty-seven consecutive patients of newly diagnosed patients with esophageal neoplasm.Making scanning with CT-sim,CT images of 37 patients with esophageal neoplasm were transfer into oncentra planning system.VMAT and IMRT of 37 patients were optimized on an oncentra teatment planning system.Gross tumor volume(GTV),planning target volume(PTV)and organs at risk were evaluated with dose-volume histogram.To appraise the difference between the technical,the paired t-test was applied.Results Compared with the s IMRT plans,PTV99%,PTV95% and Dmax coverage of VMAT plan group increased(t=0.101,0.782,0.752),PTV-D99,D95,Dmax had no significant differences(P=0.920,0.739,0.457),GTV D99,D95,Dmean decreased(t=-5.308,-4.546,-2.422,P=0.000,0.000,0.021).PTV105% coverage of VMAT plan group became lower(t=-8.216,P=0.000),sincely better.CI and HI had no significant differences(t=-0.147,P=0.884;t=2.56,P=0.89).For the organs at risk,the lung volume V20,V30,lungMLD were superior to s IMRT(t=-12.690,P=0.000;t=-2.870,P=0.007;t=-3.659,P=0.001).The spinal dose and heart were achieved with two plans,had no significant differences(P=0.743,P=0.519).The average MU was as follows : 572.33 ±97.9,754.95±177.6,decreased by 24%.Conclusion Esophageal neoplasm Patients with VMAT technology can get equivalent or superior dose distribution and make more better hot spots of GTV compared with s IMRT.Also VMATcan make V20 and V30 of lung lower,reduce MU,improve delivery efficiency significantly than IMRT.Consequently,VMAT make in the application of esophageal cancer with superior prospects for development.Part 2 Dosimetry research of injury lungs in patients with esophageal cancer treated with s IMRT and VMATObjective To observe the influence of the doses of risk organs such as 1ungs totheir functions in patients with esophageal cancer with IMRT.Methods To design sIMRT plans and VMAT plans which tumour dose are 60 Gy for 40 patients with esophageal cancer and analyze the relationships of injury of lungs and the irradiated volume of them with DVH on the conditions of 95% turmor dose covers PTV.Results Esophageal neoplasm Patients with VMAT technology can get equivalent or superior dose distribution and can make V20 and V30 of lung lower.V5,V10,V20,V30,V50,Dmean,Dmin,Dmax of lung have significant difference for radioactivity injury of lungs in these pertinent factors such as left lung and right lung of 40 patients with using VMAT,have significant difference for radioactivity injury of between lungs.Conclusions Dosimetry factors can predict well the occurrence injury of lungs.V20,V30,Dmean of lung are important factors for injury of lung.Part 3 Dosimetric verification of volumetric modulated arc therapy in esophageal neoplasm carcinoma using COMPASS 3D patient anatomy based systemObjective To investigate the dosimetric performance of COMPASS system,a novel 3D Dose Verification Using for the verification of esophageal neoplasm volumetric modulated therapy(VMAT)therapy plan.Methods Thirty-seven consecutive patients of newly diagnosed patients with esophageal neoplasm.Making scanning with CT-sim,CT images of 37 patients with esophageal neoplasm were transfer into oncentra planning system.A treatment planning system(TPS),and then these treatment plans were sent to the COMPASS and MOSAIQ system,a coherent control system,respectively.Comparison of the COMPASS reconstructed dose versus TPS dose was conducted by using the dose volume-based indices:dose received by 95%volume of target(D95),mean dose(Dmean)and γ pass rate.COMPASS can reconstruct dose with the real measured delivery fluenee after detector commissioning.Results The average dose difierence for the target volumes was within I%,the difference for D95‘was within 3%for most treatment plans,and the γ pass rate was higher than 92%for all target volumes.The average differences for the lung values of V20 and V30 were19.86±2.18,20.03±2.21)% and(12.35±2.61,12.40±2.52)%respectively.In general the COMPASS measured doses were all smaller than the TPS calculated doses for these two organs.Conclusion VMAT make in the application of esophageal cancer with superior prospects for development...