Skip to Main Content

++

INTRODUCTION

++

A practical review of basic atomic and nuclear physics is essential to understand the origins of radiations, as well as their interactions with matter. The nature and type of emissions are determined by the structural character of the atom and nucleus. The ways in which radiation interacts with matter have a direct relationship with imaging and radiation safety. This chapter will focus on atomic and nuclear structure and the interaction of radiations with matter as they relate to radionuclide imaging.

++

ATOMIC AND NUCLEAR STRUCTURE

++

Matter is composed of atoms and the characteristics of a specific form of matter are determined by the number and type of atoms that make it up. How atoms combine is a function of their electron structure. The electron structure is determined by the nuclear architecture. As we have yet to image the atom, its structure is based on a "most-probable" model that fits physical behaviors we observe. The probabilistic approach is based on the model of the atom proposed by Neils Bohr in 1913. The Bohr atom proposed a positively charged nucleus, surrounded by negatively charged electrons. A neutral atom is one in which the positive and negative charges are matched. A mismatch in these charges determines the ionic character of the atom, which is the basis for its chemistry. The electron configuration is also a source for emissions.

++

Emissions or radiations may be in either of the two forms: particulate or electromagnetic. The origins of either type of radiation may be from the nucleus or the electron structure.

++

Electron Configuration

++

Electrons are arranged around the nucleus in shells. The number of shells is determined by the number of electrons, which is, in turn, determined by the number of protons in the nucleus. The force exerted on these shells, called binding energy, is determined by the proximity of the shell to the nucleus. Higher binding energies are exerted on shells closest to the nucleus. The innermost shell is named the "K" shell and electrons in this shell are subject to the highest binding energy. The magnitude of that energy is dependent on the positive forces or number of protons in the nucleus. Shells more distant from the nucleus are named L, M, N, and so on. Each of these shells has lower binding energies as a result of their distance from the nucleus (Fig. 1-1).

++
FIGURE 1-1

Atomic structure. The nucleus is surrounded by electron shells. The binding energy decreases as the distance from the nucleus increases (K > L > M).

Graphic Jump Location
++

The radii of each of these shells increase as a function of their distance from the nucleus. An expression of this is given by assigning an integer value (1, 2, 3, …) to each shell. The lower values ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessCardiology Full Site: One-Year Subscription

Connect to the full suite of AccessCardiology content and resources including textbooks such as Hurst's the Heart and Cardiology Clinical Questions, a unique library of multimedia, including heart imaging, an integrated drug database, and more.

$595 USD
Buy Now

Pay Per View: Timed Access to all of AccessCardiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.