Purpose:The purpose of this study was to comprehensively compare the 3-dimensional(3D)magnetic resonance imaging(MRI)-guided intracavitary brachytherapy(BT)and conventional 2-dimensional(2D)point A-based intracavitary BT planning for cervical cancer with regard to target coverage and doses to adjacent organs-at risk(OARs).Methods:A total of 79 consecutive patients with cervical cancer were first treated with 2D point A-based external beam radiation therapy,and then with high-dose-rate(HDR)BT between October 2011 and April 2013 at the First Hospital Affiliated to Xian Jiao Tong University,Xian,China.The 2D and 3D treatment planning were compared the difference of the target coverage and doses to bladder,rectum and sigmoid colon.Results:In small tumors,3D BT planning resulted in significantly higher doses to target but lower doses to OARs compared with 2D planning(P<0.05).In big and eccentric tumors,doses to tumor target and OARs in 3D planning were all significantly higher than in 2D planning(P<0.05).However,for the eccentric small tumors,volume doses to OARs in 3D planning were significantly lower than in 2D planning(P<0.05).For bladder and ureter tissues invaded by tumors,the doses to target in 3D planning were significantly higher than in 2D planning(P<0.05).In 3D planning,the doses to adjacent rectum and bladder were significantly higher but those to sigmoid colon were lower than in 2D planning(P<0.05).Conclusions:3D MRI image-guided BT planning increases the dose coverage of target and reduces the HDR-BT-induced toxicity to OARs.