Fundamentals of Nuclear Medicine Dosimetry PDF
Preview Fundamentals of Nuclear Medicine Dosimetry
Fundamentals of Nuclear Medicine Dosimetry Michael G. Stabin, PhD Associate Professor, Department of Radiology/Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA Fundamentals of Nuclear Medicine Dosimetry MichaelG.Stabin,PhD AssociateProfessor DepartmentofRadiology/ RadiologicalSciences VanderbiltUniversity Nashville,TN,USA ISBN:978-0-387-74578-7 e-ISBN:978-0-387-74579-4 DOI:10.1007/978-0-387-74579-4 LibraryofCongressControlNumber:2007937210 ©2008SpringerScience+BusinessMedia,LLC. 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, LLC, 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 adaptation, computer software, or by similar or dissimilarmethodologynowknownorhereafterdevelopedisforbidden. Theuseinthispublicationoftradenames,trademarks,servicemarks,and similarterms,eveniftheyarenotidentifiedassuch,isnottobetakenasan expressionofopinionastowhetherornottheyaresubjecttoproprietary rights. Whiletheadviceandinformationinthisbookarebelievedtobetrueand 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 omissionsthatmaybemade.Thepublishermakesnowarranty,expressor implied,withrespecttothematerialcontainedherein. Printedonacid-freepaper 987654321 springer.com Preface Ifyourevealyoursecretstothewind,youshouldnotblamethe windforrevealingthemtothetrees. —FromTheProphet byKahlilGibran This was a very satisfying book to write, but also perhaps a very dangerous one. After 15 years of building a base of knowledge in radiopharmaceutical dosimetry (under the expert guidance of Evelyn Watson at the Oak Ridge Dosimetry Center), 8 years of teaching radiation protection and dosimetry at the university level (in northeastern Brazil and at Vanderbilt University in the United States), and Photo used with permission. Copyright © OregonVacationBeaches.com. AlsoseeMemorable-Beach-Vacations.com. v vi Preface authoring a number of papers and book chapters on the subject,itwasrewardingtowritedowninasingle,organized text nearly all that I have learned on this topic. My deepest desire is that this text will be found useful by members of the nuclear medicine and radiation protection community in formalizing and facilitating such calculations. After learning a technique for performing dose calculations thatmustbedoneoften,Ihaveoftenfoundwaystoautomate suchworkinsoftwaretoolsandtomakesuchtoolsavailable to others in order to help them shortcut their efforts. One ofthegreatestrewardsIhavereceivedinmyworkhasbeen to see a few of the tools and ideas that I have developed become useful to others in their routine work. In this text, I reveal practically all of my methods and secrets for practical internal dose calculations. Some enjoy keeping their methods and ideas quite private, to protect their personal interests, and such persons may consider me to be a fool for sharing all of mine so openly. I have found, however, that the open sharing of information in the scientific community leads to heightened understanding, thriving collaboration between like-minded investigators, the spawning of new ideas, and the growth and maturation of new investigators whose contributions end up benefiting us all. I trust that my efforts here will provide some small impetus toward these ends and that readers will find the information in these pages to be clear, helpful, and frequently referenced for practical use. Michael G. Stabin, PhD Contents Preface................................................ v 1. Uses of Dosimetry Information in Nuclear Medicine.......................................... 1 2. Fundamental Concepts: Calculating Radiation Dose................................... 9 3. Models and Resources for Internal Dose Calculations....................................... 33 4. Steps in Dose Calculations........................ 77 5. Case Studies...................................... 119 6. Biological Effects of Radiation.................... 171 7. Regulatory Aspects of Dose Calculations.......... 201 Index................................................. 221 vii 1 Uses of Dosimetry Information in Nuclear Medicine Diagnostic Versus Therapeutic Applications Since the earliest days after the discovery of radiation in 1895 by Wilhelm Conrad Roentgen, it has been known that exposuretoionizingradiationcanbeharmfultohumans.In any use of ionizing radiation, one must prevent or minimize the risks of the use of the radiation while allowing its beneficial applications. As we will discuss later in this book (Chapter 6), current research is challenging the paradigm thatthequantityabsorbeddoseisthebesttouseinpredicting biological effects. There are clearly complications that need to be considered in assessing the response of all biological systems to all kinds of radiation. Nonetheless, the quantity absorbed dose, which gives the energy of ionizing radiation absorbed per unit mass of tissue (or any material for that matter), is usually indicative of the probability of a delete- rious biological effect, and it is the quantity that will be studied most in this text. Thehistoryoftheuseofradioactivematerialsasbiological tracers dates to Georg de Hevesy and colleagues, who, in 1924, performed radiotracer studies of the kinetics of lead-210 (210Pb) and bismuth-210 (210Bi) in animals. Soon thereafter in 1925, Herrman Blumgart and Otto Yens evaluated blood flow rates in humans using bismuth-214. 1 2 FundamentalsofNuclearMedicineDosimetry Iodine-131andcobalt-60werediscoveredbyJohnLivingood and Glenn Seaborg, and Emilio Segre and Glenn Seaborg discoveredtechnetium-99m(99mTc)in1938.Iodine-131(131I) and 99mTc are the predominant radionuclides currently in diagnostic and therapeutic nuclear medicine studies. The 99mTc generator was developed in 1957 by W.D. Tucker and colleagues at the Brookhaven National Laboratory.1 When X-rays were first discovered by Roentgen, the idea that physicians could see internal structures of the body withoutusingascalpelwasoneofthemostexcitingmoments in medicine. Similarly, the idea of using a radioactive tracer inside of the body to transmit signals to detectors outside of the body to investigate the movements of materials in the body and thus discern physiologic, as opposed to only anatomic, information was exciting and revolutionary. The first application of nuclear medicine is diagnostic; that is, studying structures and processes to diagnose diseases and guidemedicalresponsetopotentialhumanhealthissues.The majorityofday-to-daypracticeinnuclearmedicinecontinues to involve diagnostic procedures, but radiopharmaceuticals used in nuclear medicine may also be applied in therapeutic applications; that is, administering higher levels of activity withtheintentofexploitingtheabilityofradiationtodestroy deleterious tissues in the body (cancer, inflamed joints, and other applications). In the early part of the 20th century, shortly after the discovery of radiation and radioactivity, radiation sources were used in a number of ill-advised experiments with medicalapplicationsandconsumerproducts.Dr.PaulFrame, in a historical review of the use of such applications, notes that popular locations in the United States and elsewhere attracted visitors who could bathe in springs of radioactive water or inhale radioactivity-laden air.2 Some of these sites are still in operation, surprisingly. Routine intentional exposures to radiation occurred, based on the belief that radiationcouldcure“variousformsofgoutandrheumatism, neuralgia, metallic or malarial poisoning, chronic Bright’s disease, gastric dyspepsia, chronic diarrhea, chronic skin lesions...insanity,oldage”andcreate“asplendidyouthful 1. UsesofDosimetryInformation 3 joyous life.”2 Dr. Frame notes that “Professor Bertram Boltwood of Yale explained the scientific basis for the cures in the following way: The radioactivity was “carrying electrical energy into the depths of the body and there subjectingthejuices,protoplasm,andnucleiofthecellstoan immediate bombardment by explosions of electrical atoms,” andthatitstimulated“cellactivity,arousingallsecretoryand excretory organs . . . causing the system to throw off waste products,” and that it was “an agent for the destruction of bacteria.”2 Aseriesofconsumerproductsarosethatallowed people to drink radioactive water on a regular basis in their own homes without having to travel to a spa or mine many hours away. High rates of thyroid carcinoma were observed in the 1940s and 1950s in infants treated shortly after birth forthymusenlargement.Inasimilartimeperiod,largedoses of radiation were given to the spines of subjects suffering fromankylosingspondylitis;thetreatmentwaseffective,but it was associated with a high rate of induction of leukemia. Radiologistsandradiotherapistsoperatingintheearlyyears of radiation medicine suffered high rates of leukemia and perniciousanemia.Aparticularlytragicepisodeinthehistory of the use of radiation and in the history of industrialism was the acute and chronic damage done to the radium dial painters.3 Radium was used in luminous paints in the early 1900s, and some factory workers (mainly women) ingested large amounts of radium-226 (226Ra) during the painting of theluminousdialsforwatches.Theysoondemonstratedhigh ratesofbonecancerandevenspontaneousfracturesintheir jaws and spines from cumulative radiation injury. In the early years, 226Ra was the principal radionuclide usedinradiationtherapyinwhichhigh-activitysourceswere placed on or near tumors to attempt to eradicate them (brachytherapy; with brachy coming from a Greek word meaning“closeto”).Modernexternalradiationtherapystill employs a number of brachytherapy techniques involving different radionuclides and radiation-producing machines thatdeliverhighdosesofradiationtomalignanttissueswhile minimizingdosetohealthybodytissues.Innuclearmedicine therapy, the goal is to administer compounds systemically
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