Problem Set: Ch. 4 Loveland’s textbook Student: Ashley Burleigh ONID: 932561963

(Modern Nuclear Chemistry)

Problems

4.1 Compute the amount of a radionuclide necessary to perform an experiment with a sample count rate of 1000 cpm, a detector efficiency of 33%, and a sample aliquot for counting consisting of 10% of the total isolated sample and where the percent incorporation of the nuclide into the total isolated sample was 0.5%.

4.3 Three tracers, 90-year 151Sm (0.076 MeV β−, 100% of the disintegrations and 0.022 MeV X-ray, 4%), 244.3 days 65Zn (0.33 MeV β−, 1.7% of disintegrations and 0.511 MeV γ-rays, 3.45), and 14.3 days 32P (1.71 MeV β−, 100% of the disintegrations) will be used simultaneously in a multi-tracer Problems 111 experiment. Suppose you wish to measure the uptake of these three elements in the blood of a rat and the loss of these elements to the rest of the rat’s organs and tissue from the blood. What levels of the tracer will you inject into the rat? Why? (Assume that you will withdraw 0.1 mL blood volumes every hour for 24 h. The total blood volume of an adult rat is about 15 mL.)

4.5 Compound X, molecular weight of 150 (specific activity 1.0 mCi/mmole), was checked for purity by carefully weighing 1.5 mg of the radiochemical, mixing with 1000 mg of unlabeled compound X, and recrystallizing until a constant specific activity. Radioassay gave a value of 2500 dpm/mg. What was the purity of the radiochemical in percent?

4.7 Consider two radiopharmaceuticals, A and B. Radiopharmaceutical A generates contrast in imaging by enhanced uptake in the organ of interest by uptake in this organ that is 10 times the uptake in the surrounding tissue. Radiopharmaceutical B generates contrast in imaging the same organ by reducing the uptake in the surrounding tissue by a factor of 10. Assume the organ to be imaged has a volume of 1 cm3, while the total tissue affected has a volume of 10 cm3. Assume the background counting rate in the tissue is 10 cpm/cm3. Which is the better choice for imaging, A or B and why?

4.9 What is the accumulated activity in the liver if 50 MBq of 99Tcm is injected in the body, assuming 50% is trapped by the liver and remains there? The accumulated activity is a measure of the total number of decays occurring in the organ during the time radioactivity is present in the organ. 112 Nuclear Medicine

4.11 A radionuclide decays by emitting 0.695 MeV β-particles. Its physical half-life is 14.5 days. Assume its biological half-life is 7.1 days. What is the total energy deposited per kilogram in the body in one week from the absorption of 250 MBq?