Questions

Answers

1. The percentage of radioactivity in a preparation originating from the desired radionuclide is called __________ purity.

1. radionuclidic

2. The maximum permissible amount of ⁹⁹Mo per mCi (per 37 MBq) of ^99mTc is __________.

2. 0.15 mCi (5.55 kBq) per mCi (37 MBq) of ^99mTc, with a maximum of 2.5 mCi (92.5 kBq) total, at the time of administration

3. The radionuclidic purity of ^99mTc __________ during the day because of the longer physical half-life of ⁹⁹Mo compared with ^99mTc.

3. decreases

4. An important cause of impurity in ¹²³I preparations is __________.

4. ¹²⁴I

5. A multichannel analyzer may be used to assess radionuclidic purity by evaluation of the __________ of the sample.

5. energy spectrum

6. The energies of ⁹⁹Mo photons are __________ and __________.

6. 740 keV and 780 keV

7. A simple, common method used to evaluate for the presence of ⁹⁹Mo in ^99mTc samples uses a dose calibrator and __________.

7. a lead shield (pig) to differentially absorb the low-energy photons, while allowing the energetic ⁹⁹Mo photons to pass

8. The percentage of total radioactivity present in a preparation in the desired chemical form is called the __________ purity.

8. radiochemical

9. The presence of free ^99mTcO₄^1- (pertechnetate) in a ^99mTc–red blood cell (RBC) preparation is an example of a __________ impurity.

9. radiochemical

10. In ^99mTcO₄^1- preparations, the three general forms of technetium are free pertechnetate, chelated technetium, and __________.

10. reduced hydrolyzed technetium

11. Reduced hydrolyzed technetium has a tendency to be taken up by which organ of the body?

11. the liver

12. The form of technetium that is concentrated by the thyroid and gastric mucosa is __________.

12. ^99mTcO₄^– (pertechnetate)

13. If it is suspected that gastric activity on a bleeding scan is a result of free pertechnetate, then one should image the __________ to confirm.

13. thyroid

14. The most common means of evaluating radiochemical purity is by use of __________.

14. instant thin layer chromatography

15. As a general rule of thumb for radio-pharmaceuticals made with ^99mTcO₄^-1, the radiochemical purity should be __________.

15. at least 90%

16. __________ impurity refers to the presence of nonradioactive compounds in a preparation that may interfere with the normal behavior or safety of the radiopharmaceutical.

16. chemical

17. A common source of chemical impurity that originates from the ⁹⁹Mo/^99mTcO₄^-1 generator is __________.

17. aluminum from the alumina column

18. The presence of excess amounts of aluminum in a ^99mTc–sulfur colloid preparation leads to excess uptake in this organ of the body.

18. the lungs

19. The presence of excess amounts of aluminum in a ^99mTc–methylene diphosphonate (MDP) preparation leads to excess uptake in this organ of the body.

19. the liver

20. The presence of aluminum in a generator eluate can be tested by __________.

20. indicator paper (aurintricarboxylic acid)

21. The permissible quantities of aluminum in a fission ⁹⁹Mo generator eluate are __________.

21. less than 10 mg/mL eluate

22. The presence of excess amounts of stannous ion in a ^99mTc-MDP preparation leads to excess uptake in this organ of the body.

22. the liver

23. Macroaggregated albumin should be of what particle size?

23. 90% between 10 and 90 mm diameter

24. Sulfur colloid should be of what particle size?

24. 0.1 to 1 mm

25. Fever-producing toxins that often originate in gram-negative bacteria and may contaminate radiopharmaceuticals are called __________.

25. pyrogens

26. The rapid method of testing for pyrogens is __________.

26. the limulus amebocyte lysate (LAL) assay (which uses the blood of the horseshoe crab, Limulus polyphemus)

27. The formal method of testing for pyrogens is by __________.

27. injecting the sample into rabbits and monitoring their temperature