Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology. Rachel A. Powsner

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Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology - Rachel A. Powsner

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by:The number of protons.The number of neutrons.The number of electrons in the outermost shell.The number of protons minus the number of electrons.

      2 For each of the five terms below, choose the best definition:Isobars.Isoclines.Isomers.Isotones.Isotopes.Atoms of the same element (equal Z) with different numbers of neutrons (N).Atoms of the same element (equal Z) with different numbers of protons.Atoms of different elements (different Z) with equal numbers of neutrons (N).Atoms of different elements with equal atomic mass (A).

      3 Which of the following statements are correct?There is a stable isotope of technetium.Atoms with atomic numbers (Z) > 83 are inherently unstable.For lighter elements nuclear stability is achieved with equal numbers of protons and neutrons; for heavier elements the number of neutrons exceeds the number of protons.

      4 For internal conversion to occur, the excess energy of the excited nucleus must equal or exceed:511 keV.1.022 MeV.The internal conversion coefficient.The average energy of the Auger electrons.The binding energy of the emitted electron.

      5 For an atom undergoing beta decay, the average energy of the emitted beta particles is approximately:511 keV.0.551 times the loss of atomic mass.One half of the total energy released for the individual event.One third of the maximum energy of the emitted beta particles.Equal to the average energy of the accompanying antineutrinos.

      6 You receive a dose of 99mTc measuring 370 MBq from the radiopharmacy at 10 am. Your patient does not arrive in the department until 2 pm. How much activity, in mCi, remains? (The T1/2 of 99mTc is 6 hours. The constant e = 2.718).

      7 Rank the following binding energies from greatest to least:Electron binding energy for outer shell electrons.Nuclear binding energy.Electron binding energy for inner shell electrons.

      8 True or false: The term metastable refers to an intermediate state of nuclear decay lasting longer than 10–12 seconds prior to undergoing isomeric transition.

      9 Which of the following is true regarding beta decay of a specific radioisotope:The energy of the emitted beta particle is always the same.The energy of the emitted antineutrino is always the same.The summed energy of the emitted beta particle and antineutrino is always the same.

      10 Which unit of measurement for radioactivity is defined as one radioactive decay per second?Bequerel.Millicurie.Megabequerel.

      11 10 mCi equals how many MBq?2.7 MBq.37 MBq.270 MBq.370 MBq.

      12 Lighter nuclides (Z < 83) with an excess of neutrons tend to decay by:Gamma emission.Beta minus decay.Isomeric transition.Positron emission.Alpha emission.

      13 Which of the following statements are true?An alpha particle is the same thing as a helium nucleus.Neutrinos have the same charge as an electron.X‐rays always have lower energies than gamma rays.The terms “activity” and “count rate” are the same—they express a measurement of photons per second.

      14 When orbital electrons move from an outer shell to an inner‐shell, which of the following is not trueCharacteristic X‐rays can be emitted.Auger electrons can be emitted.The atom becomes more stable.A mixture of gamma rays and internal conversion electrons can be emitted.

      1 (c)

      2 (1) d. (2) None of the above; usually used as a geological term. (3) None of the above; in nuclear medicine it refers to an element whose nucleus is in an unstable (excited) state. (4) (c). (5) (a).

      3 (b) and (c) are true. (a) is false; technetium does not have a stable form; 99Tc has a T1/2 of 2.1 × 105 year.

      4 (e).

      5 (d).

      6 6.3 mCi.

      7 Nuclear binding energy, electron binding energy for inner shell electrons, electron binding energy for outer shell electrons.

      8 True.

      9 (3).

      10 Bequerel.

      11 370 MBq.

      12 (2) Beta minus decay.

      13 (1) only.

      14 (d).

      When radiation strikes matter, both the nature of the radiation and the composition of the matter affect what happens. The process begins with the transfer of radiation energy to the atoms and molecules, heating the matter or even modifying its structure.

      If all the energy of a bombarding particle or photon is transferred, the radiation will appear to have been stopped within the irradiated matter. Conversely, if the energy is not completely deposited in the matter, the remaining energy will emerge as though the matter were transparent or at least translucent. This said, we will now introduce some of the physical phenomena involved as radiation interacts with matter, and in particular we shall consider, separately at first, the interactions in matter of both photons (gamma rays and X‐rays) and charged particles (alpha and beta particles).

      As they pass through matter, photons interact with atoms. The type of interaction is a function of the energy of the photons and the atomic number (Z) of elements composing the matter.

      Types of photon interactions in matter

       Compton scattering

       Photoelectric effect

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