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Objective:To investigate the treatment plan quality between two treatment planning systems(TPS)for volumetric modulated Arc therapy(VMAT).Materials and Methods:VMAT plans based on Varian Eclipse(Ver10.0)and Philips Pinnacle(Ver9.10)TPS were respectively generated by 10 cervical cancer with 2,3Arcs and 10 prostate cancer patients by using1,2 Arcs,controlling the gantry movement with the space of 2o and setting the same optimization constraint as soon as possible.The delivery system with VMAT was Varian Clinac iX Linac.The prescription dose of cervical cancer was 50Gy/23f for regions at high risk,and 45Gy/23f for regions at low risk;and the the prescription dose of prostate cancer was 70Gy/28f The difference of treatment plans was evaluated by dose distribution and delivery efficiency.Results:The VMAT plans of cervical cancer based on Pinnacle in the conformal indices of PTV(CI,P>0.05),and OARs(such as rectum V30,V40 and bladder V30,V40)showed slightly better than those of Eclipse TPS,and the homogeneity indices(HI)in Pinnacle were slightly worse than the Eclipse PTV(HI,P<0.05), PTV1(HI,P<0.05)and PTV1(CI,P<0.05),there were statistical difference.The MUs with 2Arcs(P<0.05)and 3Arcs(P<0.05)of the Eclipse plans had obvious advantages over the Pinnacle plans,with statistical difference,but only the MUs had obvious statistical difference(P <0.05)between the dual and three arc plans in the Eclipse TPS.The three-arcs plans in Eclipse showed an advantages relative to the dual-arcs VMAT plans and The plans quality of three arcs in Pinnacle didn't have an advantage comparing with dual arcs in cervical cancer,but MUs both the Eclipse TPS(P<0.05)and Pinnacle TPS(P>0.05)of 3Arc are more than 2Arc.The 2Arc VMAT plans of prostate cancer based on Pinnacle in His of PTV(HI,P<0.05)and bladder protection(V30&V40)are slightly better than those of the Eclipse,but the CI(P<0.05)and MU(P>0.05)of Eclispe have an obvious advantage.1Arc VMAT plans in His of PTV(HI,P < 0.05)and normal tissues protection(such as rectum V30,V40 and bladder V30,V40)are better than Eclipse TPS,but the Cis of PTV(CI,P < 0.05)of Pinnacle is slightly worse than Eclipse; Mus of single arc(P > 0.05)plan has no obvious difference in both TPSs.Overall,Mus of Pinnacle is slightly higher than those of Eclipse.And the VMAT plans of 2Arc slightly are better than 1Arc in the His,Cis and OARs between the same TPS,but all have no obvious differences.The His of the Pinnacle(P < 0.05)has a statistical significance between 2Arc and 1Arc.But Mus of 2Arc are higher than those of 1Arc,and Mus of Pinnacle(P < 0.05)have a statistical significance.Conclusion:For patients with cervical cancer and prostate cancer,the VMAT treatment plans of two TPSs could achieve clinical acceptable dose distribution.However,we will still need more simple or complex cases for further to study and determine the optimization and performance characteristics of the two commercial TPSs.