Purpose:To investigate the accuracy of brachytherapy treatment planning system(TPS)dose distribution calculations for brachytherapy employing a shielded vaginal cylindrical applicator that reduces the dose to the bladder and healthy tissues.Methods:Three brachytherapy plans of Ir-192 brachytherapy high-dose rate(HDR)source were developed using Oncentra?Brachy v4.1(Nucletron B.V.,The Netheriands)treatment planning system for the vaginal cylindrical applicator with movable shields designed to reduce dose to the bladder and healthy tissues,and were named as P0 plan,P90 plan and P180 plan respectively.P0 plan used the applicator without any shielding,P90 plan used the applicator with the 90° shielding,and P180 plan used the applicator with the 180° shielding.Irradiations were delivered by a remote afterloading brachytherapy unit(microSelectron HDR v2,Nucletron B.V.,The Netheriands).Dose distributions at treated and shielded region were calculated using TPS,and then were measured using a 2D ion chamber array dosimeter(MtriXX,IBA Dosimetry,Germany)in the transverse and coronal planes for these treatment plans.A dedicated in-house phantom was designed and used for this measurement.The measured dose distributions were compared against the TPS dose distributions using I'Mrt MatriXX software(IBA Dosimetry,Germany).Results:The dose in the shadow regions of shields decreased much more than that before shields.The measured dose distributions in the treated region(before shield shadows)were in good agreement with the TPS calculations(γ≤1:99%,criteria 3%,3mm),demonstrating the good performance of the TPS in unshielded region.The pixels withγ>1 were mainly in the regions lying close to shielding plane surface adjacent to the central tube.In the regions,the TPS dose is less than the measured dose.The maximum thickness of the regions is 6.5mm-7.5mm on the investigated planes.Conclusions:The shield in vaginal cylinder applicator can greatly decrease the dose to the organs in shielding shadow regions and spare the organs.TPS can predict the dose distributions in the treatment regions and the organs except underestimating the dose to the region close to the interface between shielded and unshielded regions.