Studies on the velocity of blood flow: I. The method utilized.

Reports the first diagnostic procedure, done in 1925, using radioactive indicators on humans. "Less well recognized is the fact that Blumgart and his coworker Otto C. Yens, then a medical student, developed the first instrumentation used in a diagnostic procedure involving radioactive indicators. The instrumentation, a modified Wilson cloud chamber, turned out to be the detector most suitable for their purpose. Blumgart also showed remarkable foresight in outlining the requirements both for a satisfactory indicator (tracer) and for a satisfactory detector--requirements that still hold true today. The Blumgart-Yens modified cloud chamber was the birth of nuclear medicine instrumentation" (Patton, Dennis D., "The birth of nuclear medicine instrumentation: Blumgart and Yens, 1925," Journal of Nuclear Medicine, 44, No. 8 [2003] 1362-1365).  Digital facsimile from PubMedCentral at this link.