was the first to propose t flow could be measured by observin at which radioisotope disappeared rrom site at which it was injected. the tissue was homogeneous, contained no concentration tracer, that the equilibrium between and tissue was immediate, andBh was removed only by blood flo1 sensed by the external detector ty, he arrived naturally at the equation where q is quantity of tracer remaining at the site, t is time, F is blood flow, V t is the volume of the tissue (not to be confused with

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... e volume of distribution of the tracer, a volume with which we shall deal later), and X is a constant expressing the ratio of the concentration of tracer in the tissue at equilibrium to its concentration in effluent blood. It is assumed that this equilibrium is established so rapidly that the tracer is held to be always distributed according to this ratio. Customarily, a semilogarithmic plot is made. Log q(t),