Compute the blood volume within the body of horse:
Problem:
A 0.6 cm^{3} solution containing 7.5 µCi /cm^{3} of ^{59}Fe was injected into the blood stream of a horse After equilibration, 1.0 cm^{3} of blood was taken out and it gave 13239 counts in 3 min. compute the blood volume within the body of horse.
Answer:
7.5 µCi /cm^{3} = 7.5×10^{-6}×3.7×10^{10} counts/s = 27.75×10^{4} cps
Total activity added to the blood = 0.6×27.75×10^{4} = 166.5×10^{4} dps
Activity of blood taken out = 13239/3×60 = 73.55 cps
Allow the volume of blood in the body of horse be X cm^{3}
As the amount of solution added to the horse body is insignificant compared to the large blood volume, it is not essential to use the Eq. (11.2). Instead, we can assume the constancy of total activity because of long half life of radiotracer that is 44.5d
73.55 X = 166.5×10^{4} or X = 2.26×10^{4} cm^{3} = 22.6 dm^{3}
Ans Horse body contains 22.6 dm^{3} of blood