Emission Tomography

The Fundamentals of PET and SPECT

Miles N. Wernick,John N. Aarsvold

• Editorial: Academic Press
• Año: 2004
• ISBN:
  9780080521879
• Categoría: Scienze biologiche
• Categoría: Biofisica

PET and SPECT are two of today's most important medical-imaging methods, providing images that reveal subtle information about physiological processes in humans and animals. Emission Tomography: The Fundamentals of PET and SPECT explains the physics and engineering principles of these important functional-imaging methods. The technology of emission tomography is covered in detail, including historical origins, scientific and mathematical foundations, imaging systems and their components, image reconstruction and analysis, simulation techniques, and clinical and laboratory applications. The book describes the state of the art of emission tomography, including all facets of conventional SPECT and PET, as well as contemporary topics such as iterative image reconstruction, small-animal imaging, and PET/CT systems. This book is intended as a textbook and reference resource for graduate students, researchers, medical physicists, biomedical engineers, and professional engineers and physicists in the medical-imaging industry. Thorough tutorials of fundamental and advanced topics are presented by dozens of the leading researchers in PET and SPECT. SPECT has long been a mainstay of clinical imaging, and PET is now one of the world's fastest growing medical imaging techniques, owing to its dramatic contributions to cancer imaging and other applications. Emission Tomography: The Fundamentals of PET and SPECT is an essential resource for understanding the technology of SPECT and PET, the most widely used forms of molecular imaging.*Contains thorough tutorial treatments, coupled with coverage of advanced topics
*Three of the four holders of the prestigious Institute of Electrical and Electronics Engineers Medical Imaging Scientist Award are chapter contributors
*Include color artwork

CHAPTER 1

Imaging Science: Bringing the Invisible to Light

ROBERT N. BECK, Department of Radiology, The University of Chicago, Chicago, Illinois

All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight.—The reason is that this, most of all the senses, makes us know and brings to light many differences between things.

Aristotle (1941, 689)

I. Preamble

II. Introduction

III. Imaging Science

IV. Fundamental and Generic Issues of Imaging Science

V. Methodology and Epistemology

VI. A View of the Future

I PREAMBLE

This book concerns emission tomography (ET), a form of medical imaging that uses radioactive materials. The purpose of this chapter is to place the highly specialized field of emission tomography within the broader context of imaging science, which has to do with natural (i.e., unaided) vision and its extension into invisible realms by means of a great variety of imaging systems. The reason is that the fundamental issues of ET are virtually identical to those that underlie other, more mature imaging modalities. Recognition of this fact has enabled researchers in ET to make use of principles, concepts, strategies, and methods developed in other areas of imaging and, thereby, accelerate progress in this field. We must expect this process to continue.

And as the quotation from Aristotle suggests, it is also of value to recognize the place of imaging science within the much broader context of epistemology—the study of the origin, nature, methods, and limits of knowledge. The reason is that much of what we have learned about ourselves and the world around us, especially during the twentieth century, has been gained through visual means, utilizing newly developed imaging methods. The ultimate limits of knowledge that can be gained by such means are unclear but appear to be bounded primarily by human imagination and ingenuity.

Finally, to foster an appreciation of the uniqueness of our times and of the opportunities for further development of biomedical imaging methods, it is of value to discuss, very briefly, both imaging science and epistemology from evolutionary and historical perspectives.

II INTRODUCTION

The history of imaging science is, indeed, brief. In fact, we might say that imaging science does not yet exist, in the sense that it is not yet recognized as an academic discipline in most universities, with a well-defined curriculum leading to a degree. (A notable exception is the Rochester Institute of Technology, which was the first institution to offer a PhD degree in Imaging Science.) On the other hand, the survival value of visual knowledge is recognized as both obvious and very ancient. For example, it is generally accepted that mollusks had very sophisticated visual systems more than 450 million years ago (Strickberger, 1995), and it is difficult to imagine the evolution of humans without vision.

In contrast, the history of epistemology and the emphasis on vision/sight as a major source of knowledge date back to antiquity. Although some may disagree with Aristotle’s claim that sight is loved above all other senses, most would agree that the desire to know is universal and, moreover, that sight/vision provides an important means for knowing. An understanding of the strengths and limitations of this mode of knowing requires, in the first instance, an understanding of the phenomena involved in natural vision.

Questions regarding the nature of light and sight were asked for several millennia and answered in similar, although incorrect, ways. For example, with minor variations on the concepts and terms employed, influential scholars such as Zoroaster, Plato, Euclid, Ptolemy, Augustine and others (Polyak, 1957; Duke-Elder, 1958; Lindberg, 1976; Park, 1997) believed that the phenomenon of sight results from the emanation of a substance from the eyes, which traverses and comingles with the intervening medium—in effect, touching objects that are seen and, in some cases, causing them harm. Although Kepler (1604/2000) finally gave a more acceptable, ray theory of light and vision in 1604, belief in the evil eye still persists in some cultures.

A more complete historical review of concepts of the nature of light would include not only the emanatists cited here, but also the notions of Newton (corpuscular theory/color), Huygens (longitudinal wave theory), Maxwell (electromagnetic wave theory), Planck (early quantum theory of radiation), Einstein (quanta/photons), and Feynman (quantum-electrodynamics).

For the purposes of this discussion, Maxwell’s (1873) theory of electromagnetism provides a very useful model for understanding the nature of light and its propagation through space and transparent material media, as well as phenomena such as reflection, refraction, and scattering. In addition, we now have at least a basic understanding of the structure and functions of the eye–brain system and of natural vision. In particular, we now know that natural vision is due to the response of the eye to a very narrow portion of the electromagnetic (EM) spectrum, called visible light, with wavelengths, approximately, from 400 to 750 nm, lying between ultraviolet and infrared.

Moreover, we are aware of certain imperfections of the visual system, which give rise to a variety of visual misperceptions and illusions, some of which are commonly employed by artists and magicians. As a consequence, although many of us may not know precisely how an artist creates the impression of a three-dimensional object on a two-dimensional surface or how a magician is able to deceive us with his visual tricks, nevertheless, we remain confident that such experiences can be explained in rational terms based on current theories of light and vision. In fact, in most circumstances of daily life we do not question what it means to see something; rather, we take our normal visual experiences largely for granted.

Despite the acknowledged value of sight/vision, in most academic circles, language is regarded as the basis for knowledge. It is important to recognize that language can be extended, elaborated and embellished endlessly without the use of instruments of any kind and used to explain the meaning and significance of what we see. Even so, certain aspects of our visual experiences are of such complexity as to defy detailed verbal description, despite the fact that language is believed to have existed throughout all human cultures for more than 40,000 years (Holden, 1998) and has been expanded continuously through the creation of new words as well as analogies and metaphors.

In contrast to language, any extension of natural vision requires the development and use of some form of instrument, or imaging system, that performs the function of mapping invisible object properties into visible images, as indicated in Figure 1. Apart from simple magnifiers and spectacles, which were being sold by street vendors in Amsterdam during the 1500s, the first significant extension of natural vision came with the development of the optical telescope and the optical microscope in the 1600s. In the hands of Galileo (1610/1989), Hooke (1665/1987), and many others, these instruments altered dramatically humans’ understanding of themselves and the world around them, revealing material objects and certain properties that are associated with visible light, but which are quite invisible ...

Índice

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Foreword
• Preface
• Acknowledgments
• Chapter 1: Imaging Science: Bringing the Invisible to Light
• Chapter 2: Introduction to Emission Tomography
• Chapter 3: Evolution of Clinical Emission Tomography
• Chapter 4: Basic Physics of Radionuclide Imaging
• Chapter 5: Radiopharmaceuticals for Imaging the Brain
• Chapter 6: Basics of Imaging Theory and Statistics
• Chapter 7: Single-Photon Emission Computed Tomography
• Chapter 8: Collimator Design for Nuclear Medicine
• Chapter 9: Annular Single-Crystal Emission Tomography Systems
• Chapter 10: PET Systems
• Chapter 11: PET/CT Systems
• Chapter 12: Small Animal PET Systems
• Chapter 13: Scintillators
• Chapter 14: Photodetectors
• Chapter 15: CdTe and CdZnTe Semiconductor Detectors for Nuclear Medicine Imaging
• Chapter 16: Application-Specific Small Field-of-View Nuclear Emission Imagers in Medicine
• Chapter 17: Intraoperative Probes and Imaging Probes
• Chapter 18: Noble Gas Detectors
• Chapter 19: Compton Cameras for Nuclear Medical Imaging
• Chapter 20: Analytic Image Reconstruction Methods
• Chapter 21: Iterative Image Reconstruction
• Chapter 22: Attenuation, Scatter, and Spatial Resolution Compensation in SPECT
• Chapter 23: Kinetic Modeling in Positron Emission Tomography
• Chapter 24: Computer Analysis of Nuclear Cardiology Procedures
• Chapter 25: Simulation Techniques and Phantoms
• Index