Since the publication of the preliminary report1 on the use of thorium solution as a pyelographic agent, many experimental investigations as to its pharmacologic action, and much clinical evidence after a year's experience in its use have led to the conclusion that it fulfils all the conditions requisite for an ideal pyelographic medium. These conditions are that the solution be nontoxic (within the ordinary limits of usage), nonirritating, opaque to the Roentgen ray, giving not only a good shadow but one of clear delineation, possess a marked degree of fluidity, and be inexpensive.
It is a well-known fact that the degree of opacity of an element to the Roentgen ray is directly proportional to its atomic weight. On this account, tthorium, being next to the heaviest known element, seemed worthy of careful study. After an exhaustive investigation of its differrnt salts and the various combinations into which they may
BURNS JE. FURTHER OBSERVATIONS ON THE USE OF THORIUM IN PYELOGRAPHY. JAMA. 1917;LXVIII(7):533-536. doi:10.1001/jama.1917.04270020197010