Questions

Answers

1. Nuclides with the same atomic number (i.e., the same number of protons) but different numbers of neutrons (e.g., ¹⁵O, ¹⁶O, ¹⁸O) are called __________.

1. isotopes

2. Two nuclides with the same atomic mass but different atomic numbers are called __________.

2. isobars

3. Two nuclides with the same number of neutrons but different atomic numbers are called __________.

3. isotones

4. What is a radionuclide?

4. a nuclide that emits particulate or photon energy to achieve a more stable energy state

5. Another name for a helium ion containing two protons and two neutrons is _________.

5. an alpha (α) particle

6. What is a beta (β) particle?

6. an electron

7. Why are alpha (α) and beta (β) particles not used for imaging?

7. They do not exit the body efficiently and thus are not detected.

8. What ratio of protons to neutrons favors beta (β) decay?

8. a low proton-to-neutron ratio, as compared with stable nuclei

9. What two particles are emitted from the nucleus during beta (β) decay?

9. a beta (β) particle (electron) and an antineutrino

10. What is the relationship between the mean energy and the maximum energy of a beta (β) spectrum?

10. The mean energy is approximately one-third of the maximum energy.

11. What ratio of protons to neutrons favors positron decay?

11. a high proton-to-neutron ratio

12. What particles are released from the nucleus during positron decay?

12. a positron (antielectron) and a neutrino

13. What is the minimum amount of nuclear energy required for positron decay?

13. 1.02 MeV

14. What is the fate of a positron?

14. to travel a short distance, combine with an electron, and be annihilated

15. When a positron is annihilated via combination with an electron, the result is the production of __________.

15. two nearly opposed 511 keV photons

16. What ratio of protons to neutrons favors electron capture decay?

16. a high proton-to-neutron ratio

17. What particle is released from the nucleus during electron capture decay?

17. a neutrino

18. What is released from the nucleus during isometric transition?

18. gamma (γ) rays

19. Other than wavelength, frequency, and energy intensity, the fundamental difference between X-rays and gamma (γ) rays is __________.

19. that X-rays are produced from energy released due to changes in the quantum levels/values of orbital electrons of an atom, while gamma (γ) rays are produced from energy shifts in the nucleus

20. When energy from a nuclear transition results in the emission of an orbital electron rather than a gamma (γ) ray, this process is called __________.

20. internal conversion

21. Internal conversion electrons increase the radiation dose to the patient because __________.

21. Energy from the electron is absorbed within the patient’s body.

22. When energy from an orbital transition results in the emission of an orbital electron rather than an X-ray, the electron is called __________.

22. an Auger electron

23. What does the term “metastable” mean?

23. when an isomeric state is long-lived (i.e., longer than 10^-12 seconds)

24. After an electron is ejected from an inner shell orbital, what occurs?

24. Outer shell electrons release energy by moving to now unoccupied, less energetic inner orbitals; the energy released by this transition is characteristic of X-ray radiation.

25. What are the two methods used to create synthetically radioactive materials?

25. Radioactive materials are produced by bombarding a target material with either ions or with neutrons.

26. A __________ is used to bombard elements with neutrons.

26. nuclear reactor

27. A __________ is used to bombard elements with protons.

27. accelerator (linear or cyclotron)

28. Name the five common cyclotron-produced radionuclides used in nuclear medicine.

28. ¹¹¹In, ¹²³I, ⁶⁷Ga, ¹⁸F, and ²⁰¹Tl

29. What is a carrier-free radioisotope?

29. a radioisotope that does not contain any nonradioactive species

30. What does the term “activity” mean?

30. the rate of disintegration of a radio-nuclide

31. The unit of radioactivity equal to 3.7 × 10¹⁰ disintegrations per second is called __________.

31. the curie (Ci)

32. What is a becquerel (Bq)?

32. The derived unit of radioactivity used by modern metric system, the SI (Système International d’unités), is called the becquerel. One becquerel is equal to one disintegration per second, or 2.7027×10^-11 Ci.