Effect of Cystone® on urinary tract stone clearance after extracoroporeal shock wave lithotripsy : a prospective, randomized, double-blind, placebo-controlled trial = Efek Cystone terhadap bersihan batu saluran kemih pasca tindakan extracorporeal shock wave lithotripsy: sebuah studi prospektif, acak, tersamar ganda, dan kontrol plasebo