The　combination　external-beam　radiotherapy　and　high-dose-rate　brachytherapy　is　a　standard　form　of　treatment　for　patients　with　locally　advanced　uterine　cervical　cancer.　Personalized　radiotherapy　in　cervical　cancer　requires　efficient　and　accurate　dose　planning　and　assessment　across　these　types　of　treatment.　To　achieve　radiation　dose　assessment,　accurate　mapping　of　the　dose　distribution　from　HDR-BT　onto　EBRT　is　extremely　important.　However,　few　systems　can　achieve　robust　dose　fusion　and　determine　the　accumulated　dose　distribution　during　the　entire　course　of　treatment.　We　have　therefore　developed　a　toolbox　(FZUImageReg),　which　is　a　user-friendly　dose　fusion　system　based　on　hybrid　image　registration　for　radiation　dose　assessment　in　cervical　cancer　radiotherapy.　The　main　part　of　the　software　consists　of　a　collection　of　medical　image　registration　algorithms　and　a　modular　design　with　a　user-friendly　interface,　which　allows　users　to　quickly　configure,　test,　monitor,　and　compare　different　registration　methods　for　a　specific　application.　Owing　to　the　large　deformation,　the　direct　application　of　conventional　state-of-the-art　image　registration　methods　is　not　sufficient　for　the　accurate　alignment　of　EBRT　and　HDR-BT　images.　To　solve　this　problem,　a　multi-phase　non-rigid　registration　method　using　local　landmark-based　free-form　deformation　is　proposed　for　locally　large　deformation　between　EBRT　and　HDR-BT　images,　followed　by　intensity-based　free-form　deformation.　With　the　transformation,　the　software　also　provides　a　dose　mapping　function　according　to　the　deformation　field.　The　total　dose　distribution　during　the　entire　course　of　treatment　can　then　be　presented.　Experimental　results　clearly　show　that　the　proposed　system　can　achieve　accurate　registration　between　EBRT　and　HDR-BT　images　and　provide　radiation　dose　warping　and　fusion　results　for　dose　assessment　in　cervical　cancer　radiotherapy　in　terms　of　high　accuracy　and　efficiency.　©　2017　Gao　et　al.This　is　an　open　access　article　distributed　under　the　terms　of　the　Creative　Commons　Attribution　License,　which　permits　unrestricted　use,　distribution,　and　reproduction　in　any　medium,　provided　the　original　author　and　source　are　credited.