,whole ,body ,counters ,,united ,,states ,,atomic ,,energy ,,commission ,dr4 ,glenn ,t4 ,seaborg1 ,chairman ,james ,t4 ,ramey ,dr4 ,gerald ,f4 ,tape ,dr4 ,samuel ,m4 ,nabrit ,wilfrid ,e4 ,johnson ,,one ,,of ,a ,,series ,,on ,,understanding ,,the ,,atom ,nuclear energy is playing a vital role in the life of every man1 woman1 and child in the ,united ,states today4 ,in the years ahead it will affect increasingly all the peoples of the earth4 ,it is essential that all ,americans gain an understanding of this vital force if they are to discharge thoughtfully their responsibilities as citizens and if they are to realize fully the myriad benefits that nuclear energy offers them4 ,the ,united ,states ,atomic ,energy ,commission provides this booklet to help you achieve such understanding4 ,illustration3 ,edward ,j4 ,brunenkant ,edward ,j4 ,brunenkant ,director ,division of ,technical ,information ,whole ,body ,counters_/,,contents #a ,,sensitive ,,detectors #b ,,the ,,geneva ,,counter #h ,,the ,,liquid ,,scintillation ,,counter #aj ,,potassium-#dj ,,in ,,human ,,bodies #ac ,,crystal ,,counters #ae ,,the ,,radium ,,story #ag ,a ,,new ,,body ,,contaminant #ba ,,protection ,,of ,,laboratory ,,personnel #bd ,,special ,,uses #ca ,,conclusion #cd ,,suggested ,,references ,,the ,,cover ,illustration3 ,whole ,body ,counters ,this smiling youngster in the chute of a large whole body counter has just emerged from the opening 7beyond her feet7 of a hollow tank of scintillation liquid1 where she lay while the radioactivity in her body was being 8counted40 ,in a minute she will step into her slippers 7on the ramp1 right7 and be ready for play4 ,the sensitive1 heavily shielded radiation-detecting equipment shown has many uses that are described in this booklet4 ,,the ,,authors ,illustration3 ,john ,h4 ,woodburn ,john ,h4 ,woodburn teaches chemistry at ,walter ,johnson ,high ,school in ,rockville1 ,md4 ,in the past he taught at ,michigan ,state ,university1 ,illinois ,state ,normal ,university1 and ,johns ,hopkins ,university4 ,he received his ,a4,b4 from ,marietta ,college1 his ,m4,a4 from ,ohio ,state ,university1 and his ,ph4 ,d4 from ,michigan ,state ,university4 ,he is the author of the book ,radioisotopes 7,j4 ,p4 ,lippincott #aifb71 which is a student's introduction to this subject4 ,illustration3 ,frederick ,w4 ,lengemann ,frederick ,w4 ,lengemann is associate professor of radiation biology at ,new ,york ,state ,veterinary ,college1 ,cornell ,university4 ,he received his ,b4,s4 and ,m4,n4,s4 from ,cornell and his ,ph4 ,d4 from the ,university of ,wisconsin4 ,he has been research associate in radiation biology and assistant professor of chemistry at the ,university of ,tennessee and formerly was a biochemist with the ,atomic ,energy ,commission1 ,division of ,biology and ,medicine4 ,whole ,body ,counters ,by ,,john ,h4 ,,woodburn and ,,frederick ,w4 ,,lengemann ,,sensitive ,,detectors ,whole body counters are sensitive radiation detecting and measuring instruments that provide information not easily obtainable otherwise about that most important of all chemical systems1 the human body4 ,they can do this because1 strange as it may seem1 every person who ever lived is slightly radioactive4 ,quickly1 accurately1 and painlessly1 whole body counters reveal the kinds and amounts of radioactive substances that have accumulated in the body from natural sources1 from man-made fallout1 or from tracer isotopes given for medical purposes4 ,they count emissions from these radioactive materials1 as do other kinds of instruments known as 8counters04 ,in contrast to devices that disclose concentrations of radioactivity in a small area or a particular organ1 whole body counters usually are used to total up the burden of radioactivity in all parts of a human body4 ,they also are distinguished from many radiation detecting instruments with the same general purpose by their large size1 their heavy shielding1 and their sensitivity to low levels of radioactivity4 ,whole body counters are useful in many studies of physiological activity in living persons and animals4 ,they have proved valuable in calculating the radiation absorbed by victims of overexposure to radioactive materials4 ,they can show a doctor how much of his patient's body is fat and how much lean4 ,whole body counters also gave medical scientists clues to the relation of potassium deficiency to muscular dystrophy and other diseases4 ,and new medical and scientific uses are being found regularly4 ,the need for an instrument that would measure whole body radioactivity was first felt in the #aibjs when the hazardous nature of radium was recognized4 ,other sorts of instruments had to be used to estimate the amount of radium that some factory workers inadvertently had absorbed while painting luminous watch dials with a radium-containing coating4 7,see pages #ae and #af47 ,but instruments then available were without adequate shielding to eliminate background radiation1 and so the measurement efforts were of limited value4 ,it was not until the #aiejs that new types of radiation-detecting instruments were designed1 making use of the discovery that some crystals1 liquids1 and plastics give off light when struck by gamma rays 7one form of radioactive emission74 ,two principal types of instruments have been developed to detect these emissions in human tissues4 ,the most common whole body counter employs a sodium iodide crystal as the radiation detector4 ,the person being examined usually sits in a tilted chair in a room that has thick steel walls to absorb background radiation4 ,during the counting period1 the crystal is centered a few inches above the subject4 ,this type is useful for examination involving low levels of radiation or emissions from more than one kind of radioactive atom4 ,in the other type the subject is surrounded by a tank of a liquid that detects gamma rays4 ,this type is faster1 but less sensitive1 than the crystal type4 ,this booklet is intended to enable you to make imaginary visits to several whole body counters1 to understand the scientific principles that are applied in their design1 to learn the interesting ways they are used1 and to appreciate the promise they hold for increasing our knowledge of ourselves and the world we live in4 ,,the ,,geneva ,,counter ,in general1 all whole body counters must have 7#a7 a mechanism that reacts to the energy emitted by some kinds of disintegrating1 or radioactive1 atoms2 7#b7 a device that displays or records these reactions2 and 7#c7 adequate shielding to exclude unwanted rays from other sources4 ,illustration3 ,figure #a ,types of whole body counters4 ,illustration3 ,a ,the subject may be seated in a chair in an iron-shielded room and under a scintillation detecting crystal4 ,illustration3 ,b ,the subject may lie in a bed that slides into the end of a hollow cylindrical tank filled with scintillation fluid4 ,illustration3 ,c ,the subject may stand in a semicylindrical double-walled tank filled with scintillation fluid4 7,see ,figure #b47 ,illustration3 ,d ,the subject may lie on a wheeled cart and be wheeled beneath a shielded detecting crystal4 ,one of the first whole body counters was shown at an atomic science conference in ,geneva1 ,switzerland1 in #aiee 7,figures #a;,d and #b74 ,while it was on display1 #dbeh visitors to the meeting climbed a set of stairs to enter a #aj-ton lead-walled chamber4 ,here they stood still for #dj seconds while the radioactive atoms in their bodies were being 8counted01 or recorded4 ,this device1 because it was the first one persons could walk into1 aroused great interest4 ,illustration3 ,figure #b ,how a 8walk-in0 whole body counter1 such as the one demonstrated at ,geneva1 works4 ,showing3 ,signal lights ,lead glass windows ,lead shield ,scintillation shield ,photomultiplier tube ,solution storage tank under platform ,shielding for the ,geneva counter consisted of #c inches of lead4 ,only the most energetic background gamma rays and cosmic rays can penetrate this amount of shielding1 and the number that do so remain almost constant during successive counting periods4 ,this constant remaining 8background0 radiation level1 once determined1 could be subtracted from the recorded number of emissions to provide the correct radiation total from the body of each person examined4 ,illustration3 ,figure #c ,typical crystals and liquid materials used to produce scintillations for whole body counters and other radiation-detecting instruments4 ,scintillation counters provide much faster recording of radiation than ,geiger counters1 and are widely used in experiments with high-energy particle accelerators1 as well as in whole body counters4 ,to detect the gamma rays emitted by radioactive atoms disintegrating within the body1 whole body counters take advantage of a property of radiation that has been known since #ahif4 ,in that year the ,english physicist ,william ,crookes discovered that ,x rays react with certain chemicals to produce fluorescence4 ,a few years later a ,new ,zealand-born physicist1 ,ernest ,rutherford 7later ,lord ,rutherford71 found that this glow consisted of many tiny individual flashes or scintillations1 each caused by the emission of a single alpha particle4 ,he laboriously counted individual flashes by observing them through a magnifying glass4 ,if you examine a luminous watch with a hand lens in a dark room1 you can see these fascinating scintillations1 just as ,rutherford saw them long ago4 ,today1 scientists have found several crystals1 liquids1 and plastics that are especially effective in showing scintillations caused by nuclear radiations4 ,one of these substances1 with the challenging name #b1b-p-phenylene bis #e-phenyloxazole1 often shortened to ,,popop1 was used in the scintillating liquid of the ,geneva counter4 ,how the flashes are detected can be appreciated by considering the infinitely small world of individual atoms and following a single atom as it disintegrates4 7,for a more complete explanation of radioactivity1 see the companion booklet ,our ,atomic ,world in this series47 ,let us assume that we are looking at a single potassium-#dj atom in the body of the person to be examined and that it is about to disintegrate4 7,potassium-#dj is naturally radioactive4 ,it is the most abundant radioisotope in our bodies47 ,in any sizable portion of potassium-#dj1 we know that half of the atoms will disintegrate over a period of #a4c billion years1 but1 since this process is random1 there is no way for us to know when any particular atom will do so4 ,however1 when it does1 one of two alternative events will occur3 either a beta particle 7that is1 an electron7 will be ejected from the nucleus1 creating an atom of nonradioactive calcium-#dj1 or the nucleus will capture one of its own orbital electrons1 resulting in creation of an atom of stable argon-#dj and the emission of a gamma ray4 7,the beta emission process occurs in #hi out of every #ajj disintegrations4 ,see ,figure #d47 ,illustration3 ,figure #d ,comparison of potassium-#dj disintegration methods4 ,assume that the particular gamma ray is traveling in the direction of the scintillating liquid in the counter4 ,remember that the gamma ray is tiny in comparison with an atom1 which is mostly empty space4 ,therefore1 any one gamma ray probably will miss all the material part of the atoms in the body of the person being studied4 ,nor will it collide with anything as it passes through his clothes and the stainless steel tank4 ,it also may fail to collide with any of the atoms in the molecules of scintillation liquid1 of course4 ,but let us assume that the one we are watching does make a hit there4 ,its total energy will be converted instantaneously to a flash of many bits or photons of light4 ,these photons radiate from the collision scene and strike a light-sensitive surface in one or more of the counter's photomultiplier tubes1 which have been placed where they can 8see0 the scintillation liquid4 ,energy transformations result1 and a tiny pulse of electricity is originated4 ,these photomultiplier devices are similar to the equipment in the familiar 8electric eye0 door openers4 ,as their name suggests1 photomultiplier tubes 7see ,figures #f and #i7 do more than merely respond to the light flashes produced in the scintillation liquid4 ,they also amplify the weak electron disturbances into electrical pulses to operate meters that record each scintillation and count the total4 ,the ,geneva counter recorded about #be of the total gamma rays emitted by each subject4 ,since this sample was a constant proportion of the total body radiation1 it could be converted to whole body measurements with about #ig reliability4 ,in addition to finding persons with actual body contamination among those counted at ,geneva1 the #aiee counter revealed some interesting sideline information4 ,people who failed to remove radium-dial watches were soon spotted4 ,and one small boy who had picked up a sample of uranium ore at a nearby exhibit 8jammed0 the instrument4 ,each of the #be persons who were found to have above-normal levels of radiation could recall having worked with radium or some other radioactive substance at some time in the past4 ,,the ,,liquid ,,scintillation ,,counter ,a visit to this type of counter recalls the first glimmers of scientific insight that the radiation in the human body could be counted4 ,in the early #aiejs1 ,frederick ,reines and ,clyde ,l4 ,cowan1 two scientists at the ,los ,alamos ,scientific ,laboratory1 ,los ,alamos1 ,new ,mexico1 built a large liquid scintillation counter hoping to prove or disprove that neutrinos really existed4 ,neutrinos are elusive1 uncharged particles with essentially no mass4 ,they had been predicted in theory nearly #bj years earlier to explain how beta particles of different energy levels can be emitted from atoms with apparently identical nuclei4 ,illustration3 ,figure #e ,illustration3 ,dr4 ,frederick ,reines 7left7 and ,dr4 ,clyde ,l4 ,cowan 7right71 co-discoverers of the neutrino1 lower a fellow worker into the first 8whole body counter01 the scintillation assembly used in their experiment4 ,below1 ,dr4 ,wright ,lanham1 inside the counter1 peers from the opening4 ,illustration3 ,figure #e1 below ,according to theory1 neutrinos are created whenever negative beta-emitting atoms are produced4 ,on this basis1 ,drs4 ,reines and ,cowan were convinced that the fission of the nuclear fuel in the reactors of the ,hanford atomic plant at ,richland1 ,washington1 should create high densities of neutrinos4 ,they went to ,hanford and set up an elegant neutrino-catching experiment that hinged on detecting and counting gamma rays of definite energy4 ,to accomplish this1 they built a large liquid scintillation detector and shielded it from stray gamma radiation4 ,as their work progressed1 someone realized that the equipment was large enough to allow a person to crawl inside4 ,after further research at the ,atomic ,energy ,commission's ,savannah ,river ,plant in ,south ,carolina1 they were successful in finding their long-sought neutrino4 ,in doing so1 they also developed the sort of instrument that can study the human body4 ,figure #f shows a person about to enter one version of a ,los ,alamos counter1 the instrument's #adj-;gallon tank of scintillation fluid1 and #de of its #ajh photomultiplier tubes4 ,when the instrument is in use1 the tank slides into1 and is shielded by1 a #bj-ton barrier of #e-;inch lead4 ,illustration3 ,figure #f ,a liquid scintillation whole body counter at ,los ,alamos ,national ,laboratory1 showing 7left7 a subject in the chute before it is slid into the shielded detector chamber4 ,below1 the same instrument's detecting assembly1 showing the photomultiplier tubes1 removed from the shielding4 ,the loading chute will hold a person #f feet #d inches tall and weighing up to #bfj pounds4 ,the subject lies in the chute as it slides into the counter4 ,a lead plug behind his head closes the end of the cylinder to add shielding4 ,counters of this type have 8panic buttons0 with which subjects may signal if they become uneasy on being confined4 ,most counts are completed in less than #e minutes1 however1 so the buttons are rarely used4 ,since the detector fluid almost completely surrounds the subject when the chute is in place1 this type of counter captures twice as large a fraction of the emitted gamma rays as does the ,geneva type4 ,each radioactive substance emits gamma rays with an energy level characteristic of that substance4 ,whole body counters are able to measure this specific energy spectrum1 or 8fingerprint01 and so identify the kind of atom producing the radiation4 ,the number of light photons produced in the scintillation fluid is proportional to the energy transferred by the incoming gamma rays4 ,for example1 gamma rays emitted by potassium-#dj have #a4df million electron volts 7,mev7 energy2 those of cesium-#acg have #j4ffj ,mev energy4 ,when both these radionuclides are producing flashes of light in the scintillation fluid at once1 the photomultiplier tubes produce two different strengths of electrical pulses4 ,electronic devices called multichannel pulse-height analyzers sort and record the number of each4 ,,potassium-#dj ,,in ,,human ,,bodies ,data from whole body counters indicate that potassium-#dj is the most abundant radionuclide in the human body4 ,our bodies also contain other naturally radioactive substances but the numbers of atoms usually present are so low 7as with radium for instance7 that they cannot be detected with whole body counters4 ,several man-made radionuclides also have found their way into body tissues and organs in quantities that sometimes are large enough to be detected and counted4 ,measurement of disintegrating potassium-#dj atoms in the tissues of a human body can be used to determine the total amount of potassium 7both radioactive and stable7 in the body4 ,it is known that potassium-#dj makes up #j4jaai of all potassium and that #aa of all disintegrating potassium-#dj atoms emit high-energy gamma rays that are measurable by the counter4 ,the method of determining the amount of potassium in a human subject is to compare the number of gamma rays from a known amount of potassium placed in a phantom1 or dummy body1 with the number counted from the human subject 7see photo on next page74 ,phantoms are artificial bodies1 approximately the size1 shape1 and density of a human body1 used for calibrating counters4 ,they are designed so the radioisotopes they contain have similar distribution to the distribution of the isotopes expected in the real body4 ,this is how a test might work3 ,counts per minute from #adj grams of potassium in the phantom #af1hjj ,counts per minute with nothing in counter 7background7 #ab1jjj ,net counts per minute from #adj grams of potassium #d1hjj ,counts per minute with a #gg-pound boy in counter #ad1djj ,background cunts per minute #ab1jjj ,net count per minute from boy #b1djj ,calculated amount of potassium in boy #gj grams ,illustration3 ,figure #g ,phantom used for iodine-#aca studies4 ,the radiation spectrum from the thyroid area in the neck is being obtained with a sodium iodide crystal1 left4 ,we can appreciate the sensitivity of whole body counters by comparing the number of gamma rays recorded by the instruments with the total number emitted from the body being counted4 ,the following data1 also simplified1 illustrate this comparison3 ,total atoms in #gj grams of potassium #a4jh #aja ,number of atoms of potassium-#dj in #gj grams of #a4c #aj potassium ,half-life of potassium-#dj in minutes #f4d #aj ,number of potassium-#dj atoms disintegrating per minute in #gj grams of potassium #ada1jjj ,number of potassium-#dj atoms disintegrating per #ae1eaj minute with emission of measurable gamma rays ,number of counts recorded #b1djj ,detection efficiency3 #b1djj #ae1eaj #ae4e ,fatty tissues are known to have a low potassium concentration and muscle tissue a higher level4 ,it is therefore apparent that potassium-#dj determinations provide a way to indicate the amount of lean muscle in any individual1 and indirectly the amount of fat4 ,estimates of the amount of fat based on the measurement of the specific gravity of the subject1 often used in the past1 have never been satisfactory4 ,not only do variable and unmeasurable air spaces change body density1 but the process of submerging a person in a tank--to determine his specific gravity by the amount of water he displaces--is a clumsy and uncomfortable one4 ,significant variations in potassium content have been found in persons suffering from muscle diseases or malfunctions4 ,for example1 a sharp drop in potassium content accompanies the profound muscle weakness that follows diabetic coma4 ,administration of potassium produces striking improvement in the condition known as familial periodic paralysis4 ,whole body counter data from a study of muscular dystrophy and myotonia atrophica patients showed there is a gradual and progressive decrease of body potassium during the unrelenting courses of these diseases4 ,otherwise healthy children of muscular dystrophy patients1 or their brothers and sisters1 also may be deficient in potassium4 ,by assisting in muscle research1 whole body counters help doctors learn more of how potassium relates to muscle function and muscle health4 ,whole body counting is an improvement over potassium determination based on chemical analysis of body fluids4 ,if counters are not used1 one way to measure body potassium is to inject a known quantity of potassium-#db 7another radioactive form of potassium71 wait until this has been uniformly mixed with the potassium already in the body1 and then record the radioactivity of a volume of blood serum4 ,from the degree of dilution of the injected potassium-#db1 the total body potassium can be calculated4 ,this widely used method is uncomfortable for the patient since it involves use of syringes to inject and withdraw fluids4 ,because about #ie of the body potassium is inside the cells1 rather than in fluids between the cells1 this method may also be inexact if the mixing process does not continue long enough4 7,see ,radioisotopes in ,medicine1 another booklet in this series1 for a full discussion of medical treatment with radioactive materials47 ,illustration3 ,figure #h ,a crystal whole body counter 8iron room0 under construction above1 and in use4 ,illustration3 ,figure #h1 below ,,crystal ,,counters ,when we visit a crystal counter1 shown under construction in ,figure #h1 walls of battleship steel #f to #h inches thick are the first things we see4 ,rather than using shielding only around the detecting instrument1 as was done in the ,geneva counter and early versions of the ,los ,alamos counter1 crystal counters have shielding around the entire counting room4 ,with this arrangement the instruments are available for adjustment and servicing4 ,this type of counter also uses a different detection device3 a solid1 rather than a liquid scintillator4 ,a large crystal1 usually of sodium iodide sensitized with thallium1 is used to convert gamma rays to light photons4 ,let us return to the shielding problem for a moment4 ,tanks of water1 bricks1 stone1 and lead have been tried by scientists seeking effective1 cheap1 and convenient shielding4 ,some early counters were built deep underground in the hope of avoiding cosmic radiation4 ,radioactive elements are so widely distributed in the rocks1 soil1 water1 and air1 however1 that there is no place where background radiation does not exist4 ,not even the crystals1 glass1 or metals used in the detection system are free of radioactivity4 ,pre-,world ,war ,,ii surplus armor plate came to be the preferred shielding material4 ,thick slabs of battleship steel were available after the war at low cost4 ,furthermore1 steel produced since the war may contain unwanted radioactivity originating in fallout from nuclear tests and make it undesirable for shielding4 ,sometimes cobalt-#fj used as a tracer to measure deterioration of blast furnace walls causes problems in postwar steel1 too1 so old warship armor is used when possible4 ,some whole body counters have additional shielding4 ,in the counter at the ,brookhaven ,national ,laboratory1 ,upton1 ,new ,york1 the steel room is lined with -inch lead sheets1 covered by thin layers of cadmium and copper4 ,the lead is intended to absorb the secondary ,x rays produced in the iron by the interaction of high-energy gamma and cosmic rays4 ,the cadmium and copper absorb the secondary radiation that is similarly produced in the lead4 ,the doors of these rooms often weigh #f tons or more4 ,a special escape hatch was built into the counter room at the ,university of ,california at ,los ,angeles1 to be used if the main door should be jammed by an earthquake4 ,in newer whole body counting laboratories1 such as the one at the ,national ,institutes of ,health1 ,bethesda1 ,md41 the steel rooms are concealed in the interior design and are so pleasantly furnished that the patient scarcely is aware of the thick walls around him4 ,illustration3 ,figure #i ,a sodium iodide crystal1 right1 and a cluster of #g photomultiplier tubes that fit under it to record its scintillations4 ,figure #i shows a sodium iodide crystal used to react with the gamma rays that traverse it4 ,to the left of the crystal is a cluster of seven photomultiplier tubes that 8watch0 for the scintillations1 convert them to electrical pulses1 and amplify them so they can be sorted1 counted1 and recorded4 ,a trace of thallium added to the sodium iodide improves its scintillation properties4 ,in addition to being of convenient size and easy to maintain1 crystal detectors have another advantage over liquid systems4 ,the energy of the incident gamma rays from crystals is more accurately indicated by the quality of the flashes of light impinging on the photomultiplier tubes4 ,if two or more radionuclides are emitting gamma rays1 a crystal detector distinguishes between their energy levels with much more precision and sensitivity than does a liquid system4 ,crystal instruments separate gamma rays differing by no more than #j4je ,mev4 ,the energies of the gamma rays emitted by nuclides have all been determined and are listed in handbooks4 ,a scientist can thus identify the data delivered by a multichannel pulse-height analyzer as coming from potassium-#dj1 zinc-#fe1 or any other nuclide4 ,counters using sodium iodide crystals intercept1 and therefore count1 a much smaller fraction of the gammas emitted by the subject's body than liquid systems1 but they also pick up a smaller amount of background4 ,when speed is important1 the liquid counter is more effective1 but the crystal counter is preferred when radionuclides emitting gammas of nearly the same energies are to be separated and counted4 ,,the ,,radium ,,story ,radium-#bbf in the human body poses unique problems for whole body counters4 ,people who have accumulated this nuclide only because of the minute amounts occurring naturally in food and water have counts of only two or three disintegrating atoms per second1 and this amount cannot be distinguished from background radiation4 ,whole body counters are useful1 however1 in diagnosing effects in persons who have been overexposed to radium4 ,these include persons who formerly were employed to paint watch dials with a luminous paint containing radium4 7,see table below47 ,illustration3 ,figure #aj ,a group of radium dial painters at work in a watch factory in #aibb4 ,almost all these employees have been identified and the living ones recently have participated in a study at ,argonne ,national ,laboratory to determine the extent of radium accumulation in their bodies4 ,whole body counters aided in their examinations4 ,excerpts from case records of one research center show the high counts found in several patients and the source of the radium or thorium 7a closely related element7 that their bodies had taken up3 ,case ,body burden in disintegrating atoms per second ,born #aijj1 drank #baj bottles of 8,radithor0 #fc1fdj in #aibgb ,born #ahig1 drank approximately #gh ounces of #cb1ghj 8,radium ,water0 in #aicbb ,born #aibe1 worked as radium chemist since #ad1hjj #aidf ,born #aibb1 radium chemist for #g years #g1jjj ,born #ahih1 two injections of 8,thorotrast0 #c1cjj for ,x-ray diagnosis ,born #ahih1 radium dial painter in watch #gb1ejj factory1 #aiah to #aiba ,born #aijb1 radium dial painter for #d months #a1ibd in #aibd ,scientists at the ,argonne ,national ,laboratory1 ,argonne1 ,illinois1 have attempted to improve crystal whole body counters so that they will be more useful in determining the amount of radium-#bbf in humans4 ,rolf ,sievert at the ,swedish ,atomic ,energy ,commission also has studied the radium-#bbf detection4 ,he devised a highly accurate whole body counter with #aj ion chambers arranged around a curved aluminum bed on which the subject rested4 ,the instrument was installed below ground to reduce the interference of background radiation4 ,illustration3 ,figure #aa ,the spectrum of gamma radiation emitted by the body of a man three years after he accidentally inhaled radium-#bbf4 ,the solid line shows the normal radiation due to potassium-#dj1 the dotted line the total from potassium-#dj and radium-#bbf4 ,showing3 ,,counts_/,,minute ,,per #ie-,,kev ,,channel ,subject ,g 7total7 ,subject ,g 7potassium-#dj7 ,a ,,new ,,body ,,contaminant ,in #aiee1 ,charles ,e4 ,miller and ,l4 ,d4 ,marinelli were measuring human potassium levels with the whole body counter at the ,argonne laboratory4 ,they were puzzled by finding several people who emitted #j4ffj-,mev gamma rays4 ,gamma rays of this energy1 which are emitted by cesium-#acg1 had not previously been detected in humans4 ,to add to the perplexity1 when the same persons were examined a few months later1 the count of these gamma rays had increased4 ,the ,argonne findings indicated strongly that radiocesium1 which is known to occur in fallout from nuclear explosions1 was finding its way into people's bodies4 7,see ,fallout from ,nuclear ,tests1 another booklet in this series47 ,,investigation ,,of ,,fallout ,,cesium ,,in ,,laplanders' ,,diet ,illustration3 ,long-lived radionuclides1 particularly cesium-#acg1 accumulate on plants4 ,illustration3 ,reindeer herds graze on lichens and mosses4 ,illustration3 ,a substantial portion of the ,laplanders' diet is reindeer meat4 ,illustration3 ,here personal data and eating habits are recorded for each person to be counted4 ,illustration3 ,a ,laplander in a whole body counter4 ,illustration3 ,the ,university of ,helsinki 7,finland7 study revealed a close correlation between the consumption of reindeer meal and the ,lapps' body burdens of cesium-#acg4 ,however1 these levels did not exceed acceptable limits4 ,illustration3 ,figure #ab ,using a whole body counter to determine radioactivity in milk4 ,the idea that this nuclide had entered the body with food later was tested by placing various foods in the whole body counter4 ,all foods tested were found to contain some cesium-#acg1 but beef and dairy products had highest levels4 ,the radiation spectra of persons of the same age but different diet habits were compared1 and correlation was found between their cesium-#acg content and the amount of dairy products they ate4 ,in ,october #aifj1 ,kurt ,liden at the ,university of ,lund in ,sweden encountered evidence of the source of cesium-#acg in humans4 ,while he was using the whole body counter at the ,university's ,radiation ,physics ,department1 ,liden found several ,norwegians whose bodies contained quantities of cesium-#acg several times higher than previously recorded4 ,he substantiated these data by counting #ae additional ,norwegians from ,oslo and #f from ,bergen4 ,the ,oslo residents averaged #ba nanocuries 7abbreviated nc7 of cesium-#acg and the ,bergen group #fj nc4 ,swedes averaged only #h nc4 7,a nanocurie is one billionth of a curie1 the standard unit of radioactivity47 ,curiosity regarding these high values in the ,norwegians led him to investigate goat cheese1 which ,norwegians consume in larger quantities than ,swedes4 ,goat cheese at that time showed a high cesium-#acg content of #da nc per kilogram4 ,in northern ,norway1 near ,bergen1 another main food is reindeer meat1 which was found to contain #bh nc of cesium-#acg per kilogram1 compared to #j4a nc per kilogram in beef4 ,these factors indicated that goat cheese and reindeer meat were responsible for the high cesium-#acg count in the ,norwegians4 ,investigation of the soil in northern ,norway revealed that it averaged #bj nc of cesium-#acg per square meter4 ,only thin covers of lichens grow in this region1 and reindeer must graze over large areas to obtain sufficient food4 ,it was obvious that cesium-#acg from fallout was collecting on lichens and then was being concentrated in the bodies of the reindeer before they were killed for meat4 ,similar studies have been conducted by scientists of the ,pacific ,northwest ,laboratory at ,richland1 ,washington1 who since #aiei have been measuring radioactivity of plants and animals in ,alaska4 ,when they found high levels of cesium-#acg in lichens and caribou1 they became interested in the body burdens of fallout isotopes in the ,eskimos4 ,a portable crystal type of whole body counter was used to measure the cesium-#acg content of ,eskimos at five villages4 ,the ,eskimos cooperated willingly2 in some communities nearly everyone accepted the invitation to be counted4 ,this table presents the results3 ,cesium-#acg 7in nanocuries7 ,village ,number of ,minimum ,maximum ,average subjects ,diomede #ab #h #ce #bb ,barrow #bei #h #aff #ea ,point ,hope #ajg #c #aai #ag ,kotzebue #acb #ag #eah #ach ,anaktuvuk #eb #hc #gai #dba 7,for comparison1 the average body burden of cesium-#acg of residents of ,richland1 ,washington1 during this period was between #e and #g nanocuries47 ,these data show that the ,eskimos who lived inland at ,anaktuvuk and ate heavily of caribou meat carried cesium-#acg burdens up to #bj times greater than ,eskimos who lived in the four villages along the coast and had more variety in their food4 7,see pages #ah and #ai for photo story of a similar project in ,finland47 ,,protection ,,of ,,laboratory ,,personnel ,for chemists or others working with arsenic1 cyanide1 or other chemical poisons1 safety depends on recognizing the materials and keeping them where they belong4 ,when accidents do happen and poisons are swallowed or breathed in1 successful treatment requires that someone find out exactly what and how much of the poisonous material was involved4 ,in the event of accidents in nuclear laboratories or reactors1 it would be equally essential to identify accurately and quickly the quantity and kind of unstable nuclides the victim has absorbed4 ,a reactor accident conceivably could add a unique hazard since neutron radiation might change the normally stable1 nonradioactive atoms in the bodies of nearby workers into radioactive ones4 ,even gold or silver fillings in their teeth might become radioactive4 ,illustration3 ,figure #ac ,a portable whole body counter used for research as well as routine monitoring of personnel in an atomic reactor installation4 ,usually gamma-emitting radionuclides can be detected in #aj minutes4 ,this counter is in almost constant use at the ,,aec's ,national ,reactor ,testing ,station in ,idaho4 ,when human tissue 7for example1 hair7 is bombarded by fast neutrons1 sulfur atoms in molecules of proteins are converted to the radionuclide phosphorus-#cb4 ,in atomic shorthand1 this reaction is3 ,s n ,p p or1 in still more abbreviated form1 ,sn1p,p4 ,phosphorus-#cb atoms do not emit gamma rays upon disintegration and so are not detected in standard whole body counters4 ,attempts are being made1 however1 to adapt some whole body counters to pick up the secondary radiations1 called bremsstrahlung1 that occur when the high-energy beta particles that are emitted by phosphorus-#cb collide with other atoms4 ,illustration3 ,figure #ad ,whole body counter record of evidence that a cyclotron worker has picked up higher-than-average quantities of radioactive zinc-#fe4 ,note how the graph shows peaks at specific energy levels identifying the radionuclides4 ,illustration3 ,figure #ae ,graphic evidence that a radioactive gas accidentally inhaled by a worker at an experimental reactor contained #c radioactive isotopes of iodine4 ,illustration3 ,figure #af ,the number of #a4ch-,mev gamma rays emitted by sodium-#bd in the body of a reactor accident victim indicates he received about #ijj rads of neutron irradiation4 ,figures #ad through #af illustrate the kind of data that whole body counters provide to help physicians care for people involved in accidents4 ,similarly1 neutron bombardment of natural sodium 7,na7 atoms in the body produces sodium-#bd4 ,this reaction is written3 ,na7n1 gamma ray7,na4 ,the #a4ch-,mev gamma rays emitted by sodium-#bd are detected effectively by whole body counters4 ,since a given neutron dose converts a known proportion of ,na atoms to ,na1 it is possible to determine how much neutron exposure a worker has received by obtaining his body count of radioactive sodium4 ,crystal type counters also were used in an interesting special case of excessive radiation exposure4 ,seven natives of the ,marshall ,islands were examined by the whole body counter at the ,argonne ,national ,laboratory in #aieg4 ,another whole body counter1 mounted in a ,navy amphibious landing ship1 was taken to ,rongelap ,atoll in the ,marshalls several times to check on the health of all the residents of the atoll4 ,these people had accumulated zinc-#fe in their bodies as a result of contamination of crabs and other food items by fallout from the ,march #aied atomic bomb tests at the ,pacific ,proving ,ground4 ,although normal radioactive decay progressively reduced the total amount of radioactivity in the area1 the ,marshallese still were carrying this nuclide in their bodies after several years4 7,see ,atoms1 ,nature1 and ,man1 another booklet in this series1 for a more complete report of this study47 ,,special ,,uses ,studies of ,new ,babies ,study of the transfer of nutrients and other substances from an expectant mother's body to that of her unborn child is one of the most challenging areas of biological research4 ,a team of scientists headed by ,n4 ,s4 ,mac,donald has used a whole body counter at the ,university of ,california at ,los ,angeles to study one aspect of this problem by comparing the concentrations of radioactive materials in newborn infants1 in babies who are born dead1 and in tissues of the mothers-to-be4 ,in these studies the scintillation crystal was placed directly beneath a plastic bassinet holding the babies4 ,twenty-eight infants1 #f to #bd hours old1 were counted for #de minutes each4 ,the only radionuclide found was the ever-present potassium-#dj4 ,the bodies of seven stillborn babies were counted for at least #aj hours each4 ,more kinds of radionuclides were found than in the living babies1 although the large counting time may have affected the results4 ,the same counting techniques were used with placental tissues from mothers of three of the stillborns4 ,the placenta is the organ that nourishes an unborn child and through which substances from the mother's bloodstream are exchanged with those in the baby's blood4 ,the graphs in ,figure #ag show data from this experiment and illustrate the method of interpreting whole body counter data4 ,when the counts per minute at each band of gamma-ray energy recorded from the placental tissues 7b7 were subtracted from corresponding values from the stillborns 7a71 it was found 7c7 that the placentas contained more of the isotopes ruthenium-#ajc1 ruthenium-#ajf1 and zirconium-#ie than did the babies that had been nurtured by these placentas4 ,the babies' bodies contained more niobium-#ie and potassium-#dj than the placentas4 ,niobium-#ie is produced by the radioactive disintegration of zirconium-#ie4 ,this suggested that zirconium-#ie atoms do not pass readily through the placenta1 but1 after they have decayed to niobium-#ie1 they pass into the baby's bloodstream easily4 ,actually1 the gamma-ray energies of zirconium-#ie and niobium-#ie are so similar that the counter cannot distinguish between them4 ,the two isotopes1 however1 were separated chemically1 and whole body spectra were prepared from samples of the pure elements4 ,the spectrum 7d7 of pure zirconium-#ie subtracted from that of pure niobium-#ie was strikingly similar to the spectrum of 8stillborn baby minus placenta0 on the graphs4 ,cesium-#acg was added to the synthetic spectrum to provide a reference mark at the #j4ffj-,mev point4 ,this revealed that the ratio of cesium-#acg to potassium-#dj is lower in babies than in adults4 ,illustration3 ,figure #ag ,results of experiment studying transfer of nutrients from an expectant mother to her unborn child4 ,research on ,body ,processes ,radioactive tracer atoms1 either natural or purposefully built into molecules of vital materials like proteins1 are revealing how these substances function in the body to produce energy or to form new tissues4 ,when we know accurately the normal totals and kinds of radioactive substances in the body1 we can undertake new kinds of tracer studies without using large amounts of additional radiation4 ,small instruments called scanners 7see ,figure #ah7 usually are used to track tracer isotopes1 but whole body counters are useful in special circumstances4 ,illustration3 ,figure #ah ,a multidetector positron scanner to record radiations with opposed pairs of detection crystals4 ,scanning devices are commonly used for noting the fate of tracer isotopes in medical diagnosis4 ,two types of adaptations enable whole body counters to locate accumulations of radioactive materials in specific organs or small portions of the body4 ,at the ,national ,institutes of ,health1 ,bethesda1 ,md41 one counter is fitted with three rows of six #ab-;by-#ab-;inch plastic blocks4 ,each block has four photomultiplier tubes to collect the scintillations from the crystal4 ,the rows are curved so as to be equally distant from the patient's body4 ,the current pulses from each of the #ah blocks can be fed individually into the pulse sorter1 counter1 and recorder4 ,thus the kinds and numbers of gamma rays from the sector of the patient adjacent to any block can be studied individually4 ,similarly1 the path and speed of the administered materials can be followed by taking recordings from the blocks sequentially4 ,at the ,u4 ,s4 ,naval ,hospital in ,bethesda1 ,md41 a whole body counter is fitted with a crystal that can be moved at controlled speed past the body of the person being studied 7,figure #ai74 ,to increase its scanning efficiency1 the crystal is fitted with a slit and a focusing device4 ,instruments record the body radioactivity visibly at timed intervals as the crystal moves along the patient's body4 ,a television screen enables the operator to observe the patient during the counting4 ,illustration3 ,figure #ai ,the ,u4 ,s4 ,naval ,hospital whole body counter1 showing the moving crystal1 left1 and instruments1 including the television screen used by the operator4 ,the moving crystal makes it possible to use this whole body counter for scanning4 ,the role of iron in preventing one form of anemia has been clarified by using iron-#ei as a tracer4 ,persons suffering from chronic infections or such blood diseases as leukemia and polycythemia vera have been checked for the amount of iron carried by their red blood cells4 ,cobalt-#fj atoms have been substituted for stable cobalt in molecules of vitamin ,b-#ab so that the way the body makes use of this vitamin can be studied4 ,similarly1 the body's use of sodium can be studied by labeling sodium chloride with sodium-#bb and then administering solutions of the tagged salt orally or by injection4 ,whole body counters used in tracer studies cause a minimum of inconvenience for the patient4 ,their sensitivity permits use of smaller quantities of radioactive material than is required with small scanning instruments4 ,those are unusual jobs for whole body counters1 however4 ,scanners or other types of instruments are used more typically in following tracer isotopes4 ,animal ,research ,illustration3 ,figure #bj ,dogs about to be examined in a whole body counter4 ,how do dogs accumulate fallout isotopes in their bodies8 ,this question was answered effectively by placing dogs in whole body counters and comparing the count from radioactive strontium-emitted gamma rays originating in their bodies with the count from a masonite phantom dog containing a known amount of radioactive strontium-#he4 ,it was found that female dogs increase their strontium retention while they are nursing newborn puppies4 ,strontium is much like calcium1 which is a major component of milk4 ,one dog measured had broken a leg in a fight4 ,the counter showed above-average strontium accumulation for this dog1 and it was conjectured that strontium1 a 8bone-seeking0 element1 had followed calcium to the point of bone repair and new bone growth4 ,illustration3 ,figure #ba ,a wild deer under a whole body counter4 ,illustration3 ,figure #bb ,graph of whole body counter survey of four different animal species1 showing differences in their retention of orally administered radioactive zinc-#fe4 ,showing ,,retention1 versus ,,time1 ,,days for ,man1 ,dog1 ,rat1 ,mouse ,figure #bb shows how animals differ in their retention of orally administered zinc-#fe1 as revealed by a whole body counter4 ,it is apparent that counters can be used to determine the differences in the metabolism of different animal species used for research4 ,standard data developed in this way can serve to reduce error that may occur if results from one species are used for interpretation of data for another species1 such as man4 ,a ,university of ,illinois project to breed meat animals with a high lean-to-fat ratio has been aided by whole body counters4 ,the tendency to deposit fat seems to be inherited1 and breeding stock with low fat content can be selected1 using 8muscle-seeking0 potassium-#dj to show the proportion of muscle in each potential parent4 ,the ,illinois counter is unique in being large enough to examine an adult steer 7,figure #bc74 ,a similar counter at ,cornell ,university has been used to study animals infested with internal parasites1 comparing them with parasite-free animals4 ,the counter revealed that a positive relationship exists between the level of parasite infestation and loss of iron-#ei-labeled blood from the digestive tract4 ,the possibility of using this method to evaluate parasite-killing drugs is being considered4 ,the ,cornell counter is kept clean by covering the animals with plastic sheeting4 ,the same counter also can serve human patients1 who are positioned in a wheeled hospital stretcher4 7,see ,figure #a;,d47 ,,conclusion ,this booklet has presented a sample of the ways whole body counters add to man's knowledge and increase his ability to manage conditions and processes important to his health and well-being4 ,radioactive substances occur naturally within our own bodies and all other materials4 ,whole body counters measure this radioactivity1 or any which may have been added from artificial sources4 ,we have seen how these sensitive instruments help to prove hypotheses difficult to verify otherwise and how they thereby may stimulate new and fruitful scientific experimentation4 ,we have learned how whole body counters add to our knowledge of normal processes in healthy bodies and detect disease or abnormalities resulting from dangerous conditions4 ,illustration3 ,figure #bc ,a ,university of ,illinois counter large enough to examine an adult steer1 above4 ,a ,cornell ,university counter used for animal-parasite studies1 below4 ,illustration3 ,figure #bc1 below ,illustration3 ,figure #bd ,a trailer-mounted whole body counter used for research4 ,school children were examined in a project to determine possible pathways by which radioactivity may enter the human body4 ,each fact uncovered by whole body counters seems to trigger more penetrating research4 ,this is how science advances4 ,and with the advance of science comes knowledge on which we may build intelligent behavior and find solutions to problems affecting our lives4 ,,suggested ,,references ,books ,environmental ,radioactivity1 ,merril ,eisenbud1 ,mc,graw-,hill ,book ,company1 ,inc41 ,new ,york4 #aifc1 #dcj pp41 #ac4ej4 ,radioactivity in ,man3 ,whole ,body ,counting and the ,effects of ,internal ,gamma ,ray-,emitting ,radioisotopes1 ,george ,r4 ,meneely 7,ed474 ,charles ,c ,thomas1 ,springfield1 ,illinois4 #aife1 #fgb pp41 #bd4ej4 ,whole ,body ,counting1 ,proceedings of the ,symposium on ,whole ,body ,counting ,held by the ,international ,atomic ,energy ,agency at the ,neue ,hofburg1 ,vienna 7,june #ab-af1 #aifa71 ,national ,agency for ,international ,publications1 #cag ,east #cdth ,street1 ,new ,york #ajjaf1 #aifb1 #ece pp41 #aj4jj4 ,how to ,detect and ,measure ,radiation1 ,harold ,s4 ,renne1 ,the ,bobbs-,merrill ,company1 ,inc41 ,new ,york1 #aifc1 #afj pp41 #c4ie4 ,an ,introduction to ,radiation ,counters and ,detectors1 ,c4 ,c4 ,h4 ,washtell1 ,george ,newnes ,ltd41 ,london1 #aifj1 #aae pp41 #g4ej4 ,liquid ,scintillation ,counting1 ,proceedings of a ,conference ,held at ,northwestern ,university 7,august #bj-bb1 #aieg71 ,carlos ,g4 ,bell1 ,jr41 and ,f4 ,newton ,hayes 7,eds471 ,pergamon ,press1 ,inc41 ,new ,york1 #aieh1 #bib pp41 #aj4jj4 ,reports ,fundamental ,nuclear ,energy ,research1 ,a ,special ,report of the ,united ,stales ,atomic ,energy ,commission 7,december #aifc71 ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington1 ,d4 ,c4 #bjdjb1 #djg pp41 #b4ej4 ,whole ,body ,counters as ,medical ,aids1 pp4 #aa-ac2 ,acute ,whole ,body ,irradiation ,effects1 pp4 #ce-da2 ,chronic ,whole ,body ,irradiation ,effects1 pp4 #db-dh4 ,radioactive ,contamination of ,materials ,used in ,scientific ,research1 ,james ,r4 ,de,voe1 ,nuclear ,science ,series ,report ,no4 #cd1 ,national ,academy of ,sciences--,national ,research ,council1 ,washington1 ,d4 ,c4 #bjdah1 #aifa1 #b4jj4 ,appendix ,,viii1 ,the ,negotiations and ,developmental ,work on ,low ,activity ,glasses for ,use in ,whole ,body ,counters1 pp4 #aji-aae4 ,articles ,liquid ,scintillation ,counting of ,c and ,h ,labeled ,amino ,acids and ,proteins1 ,m4 ,vaughan and others1 ,science1 #abf3 #ddf 7,sept4 #f1 #aieg74 ,phosphorescence in ,liquid ,scintillation ,counting of ,proteins1 ,r4 ,j4 ,herberg1 ,science1 #abh3 #aii 7,july #be1 #aieh74 ,suspension ,counting of ,carbon-#ad in ,scintillation ,gels1 ,b4 ,l4 ,funt and ,a4 ,hetherington1 ,science1 #abe3 #ihf 7,may #ag1 #aieg74 ,liquid ,scintillation ,counting of ,aqueous ,solutions of ,carbon-#ad and ,tritium1 ,j4 ,shapira and ,w4 ,h4 ,perkins1 ,science1 #aca3 #dad 7,feb4 #ab1 #aifj74 ,alone in the ,dark with a ,panic ,button3 ,purdue's ,whole ,body ,counter1 ,martin ,mann1 ,popular ,science1 #aha3 #ij 7,october #aifb74 ,counter as a ,test ,instrument1 ,w4 ,h4 ,bucksbaum1 ,electronics ,world1 #fh3 #dh 7,november #aifb74 ,spiral ,capillary ,plastic ,scintillation ,flow ,counter for ,beta ,assay1 ,b4 ,l4 ,funt and ,a4 ,hetherington1 ,science1 #abi3 #adbi 7,may #bb1 #aiei74 ,motion ,pictures ,available for loan without charge from the ,,aec ,headquarters ,film ,library1 ,division of ,public ,information1 ,u4 ,s4 ,atomic ,energy ,commission1 ,washington1 ,d4 ,c4 #bjede and from other ,,aec film libraries4 ,understanding the ,atom3 ,radiation ,detection by ,scintillation1 #cj minutes1 black and white1 sound1 #aifb4 ,produced by the ,educational ,broadcasting ,corporation under the direction of the ,,aec's ,division of ,isotopes ,development4 ,this semitechnical film describes the scintillation process4 ,solid and liquid scintillators are shown1 a description of a photomultiplier is given1 and the pulse-height analyzer principle is illustrated4 ,human ,radioactivity ,measurements1 #i minutes1 color and sound1 #aieh4 ,produced by ,,aec's ,los ,alamos ,scientific ,laboratory4 ,this film shows a method developed at ,,lasl to monitor possible intake of radiation by personnel4 ,the liquid scintillation counter is large enough to contain a man and sensitive enough to detect even the minute amounts of his natural gamma radioactivity4 ,ionizing ,radiation in ,humans1 #ae minutes1 color and sound1 #aieh4 ,produced by ,,aec's ,argonne ,national ,laboratory4 ,describes the design and operation of ,,anl's whole body counter for determining identification1 quantity1 and location of internally deposited radioelements4 ,various techniques in accumulation of data are shown4 ,liquid ,scintillation ,counting1 #ad minutes1 color and sound1 #aieh4 ,produced by the ,jam ,handy ,organization for the ,u4 ,s4 ,atomic ,energy ,commission4 ,describes the use of a liquid scintillator for counting low-energy beta emitters commonly used in biological and medical tracer experiments4 ,also describes counting techniques1 how the counters work1 and how a sample is prepared4 ,,photo ,,credits ,cover courtesy ,los ,alamos ,scientific ,laboratory 7,,lasl7 ,figure #a ,a1 ,argonne ,national ,laboratory 7,,anl72 ,b and ,c2 ,,lasl2 ,d1 ,cornell ,university4 ,figure #b ,,lasl ,figure #c ,brookhaven ,national ,laboratory 7,,bnl7 ,figure #e ,,lasl ,figure #f ,,lasl ,figure #g ,,bnl ,figure #h ,,lasl ,figure #i ,,lasl ,figure #aj ,dr4 ,charles ,e4 ,miller1 ,,anl ,figure #ab ,,lasl ,figure #ac ,national ,reactor ,testing ,station ,figure #ah ,,bnl ,figure #ai ,national ,naval ,medical ,center ,figure #bj ,,lasl ,figure #ba ,colorado ,state ,university ,figure #bc ,cornell ,university ,figure #bd ,pacific ,northwest ,laboratory ,center-spread ,professor ,j4 ,k4 ,miettinen1 ,university of ,helsinki ,this booklet is one of the 8,understanding the ,atom0 ,series4 ,comments are invited on this booklet and others in the series2 please send them to the ,division of ,technical ,information1 ,u4 ,s4 ,atomic ,energy ,commission1 ,washington1 ,d4 ,c4 #bjede4 ,published as part of the ,,aec's educational assistance program1 the series includes these titles3 ,,nuclear ,,power ,,and ,,merchant ,,shipping ,,plutonium ,,our ,,atomic ,,world ,,nuclear ,,energy ,,for ,,desalting ,,controlled ,,nuclear ,,fusion ,,whole ,,body ,,counters ,,plowshare ,,popular ,,books ,,on ,,nuclear ,,science ,,snap1 ,,nuclear ,,space ,,reactors ,,nuclear ,,reactors ,,atoms1 ,,nature1 ,,and ,,man ,,microstructure ,,of ,,matter ,,synthetic ,,transuranium ,,elements ,,computers ,,research ,,reactors ,,genetic ,,effects ,,of ,,radiation ,,power ,,from ,,radioisotopes ,,nondestructive ,,testing ,,rare ,,earths ,,food ,,preservation ,,by ,,irradiation ,,fallout ,,from ,,nuclear ,,tests ,,radioactive ,,wastes ,,radioisotopes ,,in ,,industry ,,atoms ,,at ,,the ,,science ,,fair ,,radioisotopes ,,and ,,life ,,processes ,,atomic ,,fuel ,,atomic ,,power ,,safety ,,direct ,,conversion ,,of ,,energy ,,careers ,,in ,,atomic ,,energy ,,radioisotopes ,,in ,,medicine ,,accelerators ,,nuclear ,,terms1 ,a ,,brief ,,glossary ,,neutron ,,activation ,,analysis ,,atoms ,,in ,,agriculture ,,nuclear ,,clocks ,,power ,,reactors ,,in ,,small ,,packages ,,nuclear ,,power ,,plants ,,your ,,body ,,and ,,radiation ,a single copy of any one booklet1 or of no more than three different booklets1 may be obtained free by writing to3 ,,usaec1 ,p4 ,o4 ,,box #fb1 ,,oak ,,ridge1 ,,tennessee #cghcj ,complete sets of the series are available to school and public librarians1 and to teachers who can make them available for reference or for use by groups4 ,requests should be made on school or library letterheads and indicate the proposed use4 ,students and teachers who need other material on specific aspects of nuclear science1 or references to other reading material1 may also write to the ,oak ,ridge address4 ,requests should state the topic of interest exactly1 and the use intended4 ,in all requests1 include 8,zip ,code0 in return address4 ,printed in the ,united ,states of ,america ,,usaec ,division of ,technical ,information ,extension1 ,oak ,ridge1 ,tennessee ,february #aifg ,,footnotes #a,this is mathematical shorthand for #a4jh followed by #bd zeros1 or #a4jh million billion billion4 #b,medicines such as 8,radithor0 and 8,radium ,water0 were manufactured and sold before it was known that overexposure to radioactivity was harmful4 ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text version only1 underlined or italicized text is delimited by underscores4 --,where possible1 ,,utf superscript and subscript numbers are used2 some e-reader fonts may not support these characters4 --,in the text versions only1 other superscript text is preceded by caret and delimited by brackets4 --,in the text versions only1 other subscripted text is preceded by underscore and delimited by brackets4