Objective With the Monte Carlo method to recaleulate the IMRT dose distributions from four TPS to provide a platform for independent comparison and evaluation of the plan quality.These results wiU help make a clinical decision as which TPS will be used for prostate IMRT planning.Methods Eleven prostate cancer cases were planned with the Corvus,Xio,Pinnacle and Eclipse TPS.The plans were recalculated bv Monte Cado using leaf sequences and MUs for individual plans.Dose-volume-histograms and isodose distributions were compared.Other quantities such as Dmin(the minimum dose received by 99% of CTV/PTV),Dmax(the maximum dose received by 1%of CTV/PTV),V110%,V105%,V95%(the volume of CTV/PTV receiving 110%,105%.95% of the prescription dose),the volume of rectum and bladder receiving>65 Gy and>40 Gy,and the volume of femur receiving>50 Gy were evaluated.Total segments and MUs were also compared.Results The Monte Carlo results agreed with the dose distributions from the TPS to within 3%/3 mm.The Xio,Pinnacle and Eclipse plans show less target dose heterogeneity and lower V65 and V40 for the rectum and bladder compared to the Corvus plans.The PTV Dmin is about 2 Gy lower for Xio plans than others while the Corvus plans have slightly lower female head V50(0.03%and 0.58%)than others.The Corvus plans require significantly most segments(187.8)and MUs(1264.7)to deliver and the Pinnacle plans require fewest segments(82.4)and MUs(703.6).Conclusions We have tested an independent Monte Carlo dose catculation system for dose reconstruction and plan evaluation.This system provides a platform for the fair comparison and evaluation of treatment plans to facilitate clinical decision making in selecting a TPS and beam delivery system for particular treatment sites.