Radiopacity of the cystine calculi on KUB

: To study the radiopacity of cystine calculi. We have compared them with oxalate and/or phosphate calculi on plain X-ray films (KUB). Eleven pure cystine calculi from 5 people in 4 families, and 8 oxalate and/or phosphate calculi as controls were obtained from patients by lithotomy or spontaneous discharge in Dokkyo University School of Medicine and affiliated hospitals, since 1978. The radiopacity of cystine calculi was measured by a densitometer PDA-60 (Konika Co.), comparing the density of the calculus with that of the area surrounding the calculus on KUB. All cystine calculi were easily recognized on KUB, and their densities were fairly identical with those of oxalate and/or phosphate calculi.