The use of stabilized thorium dioxide sol (thorotrast) for roentgen visualization of the liver and spleen has become a well established clinical procedure, but the question of its radioactivity and the resultant effect on the reticulo-endothelial system is far from settled. The manufacturer places a warning in each box stating that the matter should be seriously considered.
Many observers have asserted that the radioactivity of this preparation is negligible as it causes no fogging of a film in many hours' time, but this is far too crude a method of detecting small quantities of radiation.
The Geiger counter.1 when brought in the vicinity of a sample of thorium dioxide sol, showed such violent and immediate response that I at once realized that I had a means of making observations of comparatively high accuracy. Though the instrument described is capable of making only gamma ray tests, it is substantial and
TAFT RB. THE RADIOACTIVITY OF THORIUM DIOXIDE SOLA PRELIMINARY REPORT. JAMA. 1937;108(21):1779–1781. doi:10.1001/jama.1937.02780210019005
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