RADIOACTIVE ISOTOPES IN THE STUDY OF PERIPHERAL VASCULAR DISEASE: II. Method of Evaluation of Various Forms of Treatment

EVALUATION of the peripheral circulation can be accomplished with the use of radioactive isotopes.¹ Determination of a circulatory index depends on the rate of deposition of radioactive phosphorus (P³² as a phosphate ion, in either phosphoric acid [H₃PO₄] or sodium phosphate [Na₂HPO₄]) in the tissues of an extremity; the index is then derived from a semilogarithmic plotting of the minute by minute increase in radioactivity in a selected site in the extremity (usually the sole of the foot). For statistical purposes, the reciprocal of the rate of deposition is used to calculate this index, according to the equations

where C₂₀ is the theoretic number of counts at the end of twenty minutes and C₂ is the theoretic number of counts at the end of two minutes.

In a series of normal persons, the mean rate of deposition of radioactive phosphorus in the tissues was actually less than in