We propose to use the transrectal ultrasound (TRUS) and a novel robot, the TRUS robot, to hold and manipulate the TRUS probe to monitor the extent of the vaporization or enucleation of the prostate gland intraoperatively. TRUS has been extensively used for the biopsy needle guidance during prostate biopsy. However, it has never been used during transurethral prostate procedure. The TRUS Robot has been used safely in the current clinical trial, NA_00027540, Ultrasound-Guided Navigation in Robot-Assisted Laparoscopic Radical Prostatectomy. We would like to study the feasibility and safety of using TRUS and the TRUS Robot to monitor the minimally invasive treatment of BPH, such as GreenLight PVP.