1. A method for locating an implant in an ultrasound coordinate system, comprising: obtaining positions of a plurality of implants in a fluoroscopy coordinate system; estimating positions of said plurality of implants in an ultrasound coordinate system; using a processor to determining determine an initial transformation matrix based at least in part on said obtained positions and said estimated positions of said plurality of implants; using the processor to determine a position of one of said implants in said ultrasound coordinate system based at least in part on said initial transformation, wherein said position of said one of said implants is determined without requiring use of a plurality of markers that are different from the plurality of implants; and storing said determined position in a non-transitory medium or displaying said determined position on a screen.