Holmium: Holmium. An element of the rare earth family of metals. It has the atomic symbol Ho, atomic number 67, and atomic weight 164.93.Lasers, Solid-State: Lasers which use a solid, as opposed to a liquid or gas, as the lasing medium. Common materials used are crystals, such as YAG (YTTRIUM aluminum garnet); alexandrite; and CORUNDUM, doped with a rare earth element such as a NEODYMIUM; ERBIUM; or HOLMIUM. The output is sometimes additionally modified by addition of non-linear optical materials such as potassium titanyl phosphate crystal, which for example is used with neodymium YAG lasers to convert the output light to the visible range.Lithotripsy, Laser: Fragmentation of CALCULI, notably urinary or biliary, by LASER.Ureteroscopes: Endoscopes for examining the interior of the ureter.Laser Therapy: The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.Ureteroscopy: Endoscopic examination, therapy or surgery of the ureter.Pentanones: 5-carbon straight-chain or branched-chain ketones.Cystoscopes: Endoscopes for visual examination of the urinary bladder.Ureteral Calculi: Stones in the URETER that are formed in the KIDNEY. They are rarely more than 5 mm in diameter for larger renal stones cannot enter ureters. They are often lodged at the ureteral narrowing and can cause excruciating renal colic.Transurethral Resection of Prostate: Removal of all or part of the PROSTATE, often using a cystoscope and/or resectoscope passed through the URETHRA.