Basics of PET Imaging

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Basics of PET Imaging

Physics, Chemistry, and Regulations

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Gopal B. Saha, PhD

Department of Molecular and Functional Imaging, The Cleveland Clinic Foundation, Cleveland, Ohio

Basics of PET Imaging

Physics, Chemistry, and Regulations

With 64 Illustrations

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Gopal B. Saha, PhD

Department of Molecular and Functional Imaging The Cleveland Clinic Foundation

Cleveland, OH 44195 USA

Library of Congress Cataloging-in-Publication Data Saha, Gopal B.

Basics of PET imaging physics, chemistry, and regulations / Gopal B. Saha.

p. ; cm.

Includes bibliographical references and index.

ISBN 0-387-21307-4 (alk. paper)

1. Tomography, Emission. 2. Medical physics.

[DNLM: 1. Tomography, Emission-Computed–methods. 2. Prospective Payment System. 3. Radiopharmaceuticals. 4. Technology, Radiologic. 5. Tomography, Emission-Computed–instrumentation. WN 206 S131b 2004] I. Title.

RC78.7.T62S24 2004 616.07¢575—dc22

2004048107 ISBN 0-387-21307-4 Printed on acid-free paper.

All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, Inc., 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adap- tation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden.

The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identiﬁed as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.

While the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.

Printed in the United States of America. (BS/EB) 9 8 7 6 5 4 3 2 1 SPIN 10987100 springeronline.com

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To my

teachers, mentors, and friends

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Preface

From the early 1970s to mid-1990s, positron emission tomography (PET) as a diagnostic imaging modality had been for the most part used in ex- perimental research. Clinical PET started only a decade ago.⁸²Rb-RbCl and

18F-Fluorodeoxyglucose were approved by the U.S. Food and Drug admin- istration in 1989 and 1994, respectively, for clinical PET imaging. Reim- bursement by Medicare was approved in 1995 for ⁸²Rb-PET myocardial perfusion imaging and for ¹⁸F-FDG PET for various oncologic indica- tions in 1999. Currently several more PET procedures are covered for reimbursement.

Based on the incentive from reimbursement for PET procedures and accurate and effective diagnosis of various diseases, PET centers are growing in the United States and worldwide. The importance of PET imaging has flourished to such a large extent that the Nuclear Medicine Technology Certification Board (NMTCB) is planning to introduce a PET specialty examination in 2004 for nuclear medicine technologists, as well as an augmented version of the PET specialty examination in 2005 for regis- tered radiographers and radiation therapy technologists. Courses are being offered all over the country to train physicians and technologists in PET technology. Many books on clinical PET have appeared in the market, but no book on the basics of PET imaging is presently available. Obviously, such a book is needed to fulfill the requirements of these courses and certifications.

This book focuses on the fundamentals of PET imaging, namely, physics, instrumentation, production of PET radionuclides and radiopharmaceuticals, and regulations concerning PET. The chapters are concise but comprehensive enough to make the topic easily understandable.

Balanced reviews of pertinent basic science information and a list of suggested reading at the end of each chapter make the book an ideal text on PET imaging technology. Appropriate tables and appendixes include data and complement the book as a valuable reference for nuclear medicine professionals such as physicians, residents, and technologists. Technologists and residents taking board examinations would

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beneﬁt most from this book because of its brevity and clarity of content.

The book contains 11 chapters. The subject of each chapter is covered on a very basic level and in keeping with the objective of the book. It is assumed that the readers have some basic understanding of physics and chemistry available in standard nuclear medicine literature. At the end of each chapter, a set of questions is included to provoke the reader to assess the sufﬁciency of knowledge gained.

Chapter 1 brieﬂy reviews the structure and nomenclature of the atoms, radioactive decay and related equations, and interaction of radiation with matter. This is the gist of materials available in many standard nuclear medicine physics book. Chapter 2 describes the properties of various detectors used in PET scanners. Descriptions of PET scanners, hybrid scintillation cameras, PET/CT scanners, small animal PET scanners, and mobile PET scanners from different manufacturers as well as their features are given. Chapter 3 details how two-dimensional and three-dimensional data are acquired in PET and PET/CT imaging. Also included are the different factors that affect the acquired data and their correction method. Chapter 4 describes the image reconstruction technique and storage and display of the reconstructed images. A brief reference is made to DICOM, PACS, and teleradiology. The performance characteristics of different PET scanners such as spatial resolution, sensitivity, scatter fraction, and so on, are given in Chapter 5. Quality control tests and acceptance tests of PET scanners are also included. Chapter 6 contains the general description of the princi- ples of cyclotron operation and the production of common PET radionuclides. The synthesis and quality control of some common PET radiopharmaceuticals are described in Chapter 7. Chapter 8 covers pertinent regulations concerning PET imaging. FDA, NRC, DOT, and state regulations are discussed. In Chapter 9, a historical background on reimbursement for PET procedures, and different current codes for billing and the billing process are provided. Chapter 10 outlines a variety of factors that are needed in the design of a new PET center. A cost estimate for setting up a PET facility is presented. Chapter 11 provides protocols for four common PET and PET/CT procedures.

I do not pretend to be infallible in writing a book with such signiﬁcant scientiﬁc information. Errors of both commission and omission may have occurred, and I would appreciate having them brought to my attention by the readers.

I would like to thank the staff in our Department of Molecular and Functional Imaging for their assistance in many forms. I am grateful to Ms.

Lisa M. Saake, Director of Healthcare Economics, Tyco Healthcare/

Mallinckrodt Medical, for her contribution to Chapter 9 in clarifying several issues regarding reimbursement and reshaping the front part of the chapter.

It is beyond the scope of words to express my gratitude to Mrs. Rita Konyves, who undertook the challenge of typing and retyping the manu- viii Preface

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script as much as I did in writing it. Her commitment and meticulous effort in the timely completion of the manuscript deserves nothing but my sincere gratitude and thanks.

I am grateful and thankful to Robert Albano, Senior Clinical Medical Editor, for his suggestion and encouragement to write this book, and others at Springer for their support in publishing it.

Cleveland, OH Gopal B. Saha, PhD

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Contents

xi

Preface . . . . vii

1. Radioactive Decay and Interaction of Radiation with Matter . . . . 1

Atomic Structure . . . . 1

Radioactive Decay . . . . 2

Radioactive Decay Equations . . . . 5

General Decay Equations . . . . 5

Successive Decay Equations . . . . 7

Units of Radioactivity . . . . 9

Units of Radioactivity in System Internationale . . . . 9

Calculations . . . . 9

Interaction of Radiation with Matter . . . . 10

Interaction of Charged Particles with Matter . . . . 10

Interaction of g Radiation with Matter . . . . 12

Attenuation of g Radiations . . . . 14

Questions . . . . 16

References and Suggested Reading . . . . 18

2. PET Scanning Systems . . . . 19

Background . . . . 19

Solid Scintillation Detectors in PET . . . . 20

Photomultiplier Tube . . . . 23

Pulse Height Analyzer . . . . 24

Arrangement of Detectors . . . . 25

PET Scanners . . . . 28

Hybrid Scintillation Cameras . . . . 29

PET/CT Scanners . . . . 30

Small Animal PET Scanner . . . . 34

Mobile PET or PET/CT . . . . 36

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3. Data Acquisition and Corrections . . . . 39

Data Acquisition . . . . 39

Two-Dimensional Versus 3-Dimensional . . . . 43

PET/CT Data Acquisition . . . . 45

Factors Affecting Acquired Data . . . . 47

Normalization . . . . 47

Photon Attenuation . . . . 48

Random Coincidences . . . . 53

Scatter Coincidences . . . . 54

Dead Time . . . . 55

Radial Elongation . . . . 56

4. Image Reconstruction, Storage and Display . . . . 59

Simple Backprojection . . . . 59

Filtered Backprojection . . . . 61

The Fourier Method . . . . 62

Types of Filters . . . . 64

Iterative Reconstruction . . . . 67

3-D Reconstruction . . . . 70

Partial Volume Effect . . . . 70

Storage . . . . 72

Display . . . . 73

Software and DICOM . . . . 74

PACS . . . . 76

Teleradiology . . . . 79

5. Performance Characteristics of PET Scanners . . . . 81

Spatial Resolution . . . . 81

Sensitivity . . . . 84

Noise Equivalent Count Rate . . . . 86

Scatter Fraction . . . . 87

Contrast . . . . 87

Quality Control of PET Scanners . . . . 89

Daily Quality Control Tests . . . . 89

Weekly Quality Control Tests . . . . 89

Acceptance Tests . . . . 90

Spatial Resolution . . . . 92

Scatter Fraction . . . . 93

Sensitivity . . . . 94

Count Rate Losses and Random Coincidences . . . . 95

References and Suggested Reading . . . . 97 xii Contents

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6. Cyclotron and Production of PET Radionuclides . . . . 99

Cyclotron Operation . . . . 99

Medical Cyclotron . . . . 101

Nuclear Reaction . . . . 102

Target and its Processing . . . . 103

Equation for Production of Radionuclides . . . . 104

Speciﬁc Activity . . . . 106

Production of Positron-Emitting Radionuclides . . . . 106