Compute the blood volume within the body of horse:
Problem:
A 0.6 cm3 solution containing 7.5 µCi /cm3 of 59Fe was injected into the blood stream of a horse After equilibration, 1.0 cm3 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 /cm3 = 7.5×10-6×3.7×1010 counts/s = 27.75×104 cps
Total activity added to the blood = 0.6×27.75×104 = 166.5×104 dps
Activity of blood taken out = 13239/3×60 = 73.55 cps
Allow the volume of blood in the body of horse be X cm3
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 = 166.5×104 or X = 2.26×104 cm3 = 22.6 dm3
Ans Horse body contains 22.6 dm3 of blood