Essentials of Nuclear Medicine and Molecular Imaging E-Book

Fred A. Mettler, Milton J. Guiberteau

• Publisher: Saunders
• Year: 2018
• ISBN:
  9780323567893
• Edition: 7
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

Covering both the fundamentals and recent developments in this fast-changing field, Essentials of Nuclear Medicine and Molecular Imaging, 7th Edition, is a must-have resource for radiology residents, nuclear medicine residents and fellows, nuclear medicine specialists, and nuclear medicine technicians. Known for its clear and easily understood writing style, superb illustrations, and self-assessment features, this updated classic is an ideal reference for all diagnostic imaging and therapeutic patient care related to nuclear medicine, as well as an excellent review tool for certification or MOC preparation.

• Provides comprehensive, clear explanations of everything from principles of human physiology, pathology, physics, radioactivity, radiopharmaceuticals, radiation safety, and legal requirements to hot topics such as new brain and neuroendocrine tumor agents and hybrid imaging, including PET/MR and PET/CT.
• Covers the imaging of every body system, as well as inflammation, infection and tumor imaging; pearls and pitfalls for every chapter; and pediatric doses and guidelines in compliance with the Image Gently and Image Wisely programs.
• Features a separate self-assessment section on differential diagnoses, imaging procedures and artifacts, and safety issues with unknown cases, questions, answers, and explanations.
• Includes new images and illustrations, for a total of 430 high-quality, multi-modality examples throughout the text.
• Reflects recent advances in the field, including updated nuclear medicine imaging and therapy guidelines • Updated dosimetry values and effective doses for all radiopharmaceuticals with new values from the 2015 International Commission on Radiological Protection • Updated information regarding advances in brain imaging, including amyloid, dopamine transporter and dementia imaging • Inclusion of Ga-68 DOTA PET/CT for neuroendocrine tumors • Expanded information on correlative and hybrid imaging with SPECT/CT • New myocardial agents • and more.
• Contains extensive appendices including updated comprehensive imaging protocols for routine and hybrid imaging, pregnancy and breastfeeding guidelines, pediatric dosages, non-radioactive pharmaceuticals used in interventional and cardiac stress imaging, and radioactivity conversion tables.

1

Radioactivity, Radionuclides, and Radiopharmaceuticals

Chapter Outline

• Basic Isotope Notation
  • Nuclear Stability and Decay
• Radionuclide Production
• Radioactive Decay
• Radionuclide Generator Systems
• Radionuclides and Radiopharmaceuticals for Imaging
  • Single Photon
  • Positron Emitters
  • Biologic Agents and Nanoparticles
  • Adverse Reactions
  • Investigational Radiopharmaceuticals
• Radiopharmacy Quality Control
  • Generator and Radionuclide Purity
  • Radiochemical Labeling
• Unsealed Radionuclides Used for Therapy
  • Phosphorus-32, Yttrium-90, and Gold-198
  • Iodine-131
  • Strontium-89, Samarium-153, Rhenium-186, and Radium-223

Basic Isotope Notation

The atom may be thought of as a collection of protons, neutrons, and electrons. The protons and neutrons are found in the nucleus, and shells of electrons orbit the nucleus with discrete energy levels. The number of neutrons is usually designated by N. The number of protons is represented by Z (also called the atomic number). The atomic mass number, or the total number of nuclear particles, is represented by A and is simply the sum of N and Z. The symbolism used to designate atoms of a certain element having the chemical symbol X is given by

. For example, the notation

refers to a certain isotope of iodine. In this instance, 131 refers to the total number of protons and neutrons in the nucleus. By definition, all isotopes of a given element have the same number of protons and differ only in the number of neutrons. For example, all isotopes of iodine have 53 protons.

Nuclear Stability and Decay

A given element may have many isotopes, and some of these isotopes have unstable nuclear configurations of protons and neutrons. These isotopes often seek greater stability by decay or disintegration of the nucleus to a more stable form. Of the known stable nuclides, most have even numbers of neutrons and protons. Nuclides with odd numbers of neutrons and protons are usually unstable. Nuclear instability may result from either neutron or proton excess. Nuclear decay may involve a simple release of energy from the nucleus or may actually cause a change in the number of protons or neutrons within the nucleus. When decay involves a change in the number of protons, there is a change of element. This is termed a transmutation. Isotopes attempting to reach stability by emitting radiation are radionuclides.

Several mechanisms of decay achieve stability. One of these is alpha-particle emission. In this case, an alpha (α) particle, consisting of two protons and two neutrons, is released from the nucleus, with a resulting decrease in the atomic mass number (A) by four and reduction of both Z and N by two. The mass of the released alpha particles is so great that they travel only a few centimeters in air and are unable to penetrate even thin paper. These properties cause alpha-particle emitters to be essentially useless for imaging purposes.

Beta-particle emission is another process for achieving stability and is found primarily in nuclides with a neutron excess. In this case, a beta (β−) particle (electron) is emitted from the nucleus accompanied by an antineutrino; as a result, one of the neutrons may be thought of as being transformed into a proton, which remains in the nucleus. Thus, beta-particle emission decreases the number of neutrons (N) by one and increases the number of protons (Z) by one, so that A remains unchanged (Fig. 1.1). When Z is increased, the arrow in the decay scheme shown in Fig. 1.1 points toward the right, and the downward direction indicates a more stable state. The energy spectrum of beta-particle emission ranges from a certain maximum down to zero; the mean energy of the spectrum is about one-third of the maximum. A 2-MeV beta particle has a range of about 1 cm in soft tissue and is therefore not useful for imaging purposes.

Fig. 1.1 Decay schemes of radionuclides from unstable states (top line of each diagram) to more stable states (bottom line).

Electron capture occurs in a neutron-deficient nuclide when one of the inner orbital electrons is captured by a proton in the nucleus, forming a neutron and a neutrino. This can occur when not enough energy is available for positron emission, and electron capture is therefore an alternative to positron decay. Because a nuclear proton is essentially changed to a neutron, N increases by one, and Z decreases by one; therefore, A remains unchanged (see Fig. 1.1). Electron capture may be accompanied by gamma emission and is always accompanied by characteristic radiation, either of which may be used in imaging.

If, in any of these attempts at stabilization, the nucleus still has excess energy, it may be emitted as nonparticulate radiation, with Z and N remaining the same. Any process in which energy is given off as gamma rays and in which the numbers of protons and neutrons are not changed is called isomeric transition (see Fig. 1.1). An alternative to isomeric transition is internal conversion. In internal conversion, the excess energy of the nucleus is transmitted to one of the orbital electrons; this electron may be ejected from the atom, which is followed by characteristic radiation when the electron is replaced. This process usually competes with gamma-ray emission and can occur only if the amount of energy given to the orbital electron exceeds the binding energy of that electron in its orbit.

The ratio of internal conversion electrons to gamma-ray emissions for a particular r...