3- Nuclear Medicine Physics and Techniques (IS-NUM 401) Atomic and nuclear physics .pdf

Nuclear Medicine Physics and Techniques IS-NUM 401 Fall 2024 - 2025 Dr. Mohamed Zakaria El-Sayed Assistant Professor of Medical Imaging Sciences BSc. Medical Imaging Science...

Nuclear Medicine Physics and Techniques IS-NUM 401 Fall 2024 - 2025 Dr. Mohamed Zakaria El-Sayed Assistant Professor of Medical Imaging Sciences BSc. Medical Imaging Sciences (MIS) College of Health Sciences September 5, 2024 www.gmu.ac.ae COLLEGE OF ALLIED HEALTH SEIENCES  Lecture 2 Atomic and Nuclear Physics LEARNING OBJECTIVES After completing this lecture, the student will be able to know: 1. Basics of atomic and nuclear physics. 2. Nucleus and concept of nuclear stability and radioactivity. 3. Concept of nuclear binding energy and mass defect. Structure of the Atom An atom is negatively charged electrons arranged in defined shells about a positively charged central nucleus.  Atomic Structure The electrical charges of the atom are “balanced” that is the total negative charge of the electrons equals the positive charge of the nucleus (No. of Orbital Electrons = No. of Nuclear Protons) The atom as a whole is electrically neutral.  Structure of a nucleus Nucleus The nucleus is the positively charged center of an atom, contains most of the atom's mass, and is composed of protons and neutrons. Proton ❑ Proton’s (+) charge is equal to the electron (-) but opposite in charge. ❑A proton has a mass of 1.67 x 10-27 kilograms. Neutron ❑ The neutron carries no electrical charge ❑ It has the same mass as the proton Nucleus and nuclear stability Nuclear stability It refers to the stability of the nucleus of the atom. A stable nucleus does not decay spontaneously. Radioactive elements contain unstable nuclei and decay spontaneously emitting various types of radiations. Nucleus and nuclear stability Nuclear stability The nucleus of an atom is tiny, in such a small place, neutrons and protons are held together. Although protons are all positively charged they don’t get repelled. This represents a certain force that affects nuclear stability. Nucleus and nuclear stability Nuclear stability Some of the factors that affect nuclear stability are: ❑ Nuclear forces ❑ Mass defect and nuclear binding energy ❑ The neutron-to-proton ratio (N/Z ratio)  Nucleus and nuclear stability Nuclear Forces The forces which hold the nucleons together within the nucleus. These are short-range forces. The stable nucleus does not take part in the chemical reaction. In the presence of such strong forces, very high energy is required to break the nucleus which is called Nuclear Binding Energy. Nuclear Binding Energy and Mass Defect Nuclear strong force results from the phenomenon known as mass defect. Direct measurements show that the mass of the nucleus is less than the sum of the individual masses of the constituent protons and neutrons (nucleons). Nuclear Binding Energy and Mass Defect Using the Einstein relationship, the deficient mass equals the energy required to separate the nucleons or binding energy Eb of the nucleus. Denoted by △m, measured in atomic mass unit (AMU) The higher the binding energy, the more stable the nucleus. Denoted by E, measured in MeV (million electron volts) or J (Joule) Einstein’s Equation  Radioactivity Radioactivity is the spontaneous emission of particles and photons as a result of nuclear instability. An unstable nucleus will decay and adjust itself until it is stable either by: 1. Ejecting portions of its nucleus. 2. Emitting energy in the form of photons (gamma rays). This process is referred to as radioactive decay.  Radioactivity Common units for measuring radioactivity are the curie (Ci) or the international system (SI) unit becquerel (Bq). One becquerel is defined as one radioactive decay per second (d/s). One curie (Ci) is defined as 3.7×1010 (d/s).  The neutron-to-proton ratio (N/Z ratio) The N/P ratio refers to the ratio of the number of neutrons to protons. This ratio is a crucial factor in determining the stability of a nucleus. Stable nuclei tend to have roughly equal numbers of protons and neutrons.  The Stable Nucleus In nuclei with a stable state there is an optimal ratio of neutrons to protons. For the lighter elements, this ratio is approximately 1:1 For increasing atomic weights, the number of neutrons exceeds the number of protons. A plot referring to the ratio of neutrons and protons is called the line of stability.  For example, light elements like hydrogen have a neutron- to-proton ratio of roughly 1:1, while heavier elements like uranium may have a higher ratio. Larger elements tend to have a larger N/P ratio (closer to 2:1) References and Text Books Khalil, M.M. ed., 2021. Basic sciences of nuclear medicine. Springer Nature. Pryma, D.A., 2014. Nuclear medicine: practical physics, artifacts, and pitfalls. Oxford University Press, USA. Cherry, S.R., Sorenson, J.A. and Phelps, M.E., 2013. Physics in nuclear medicine (pp. 209-211). Saunders. Suggested Reading Ell P, Gambhir S, editors: Nuclear Medicine in Clinical Diagnosis and Treatment, ed 3, Edinburgh, Scotland, 2004, Churchill Livingstone. Sandler MP, Coleman RE, Patton JA, et al, editors: Diagnostic Nuclear Medicine, ed 4, Baltimore, 2002, Williams & Wilkins. Schiepers C, editor: Diagnostic Nuclear Medicine, ed 2, New York, 2006, Springer. Von Schulthess GK, editor: Molecular Anatomic Imaging: PET-CT and SPECT-CT Integrated Modality Imaging, ed 2, Philadelphia, 2006, Lippincott, Williams and Wilkins.  Contacts Mobile: +971 508 22 6100 Personal email: [email protected] Academic email: [email protected] https://www.linkedin.com/in/mohamed-zakaria-ahmed-rad- mit-phd-395299a6/ Mohamed Zakaria Ahmed Rad., MI PhD | LinkedIn