核技術(shù)導(dǎo)論英文課件：Chapter 8 Radioactive isotopes and Their Applications

1、Chapter 8. Radioactive isotopes and Their Applications Introduction Production of Radioisotopes Some Commonly Used Radionuclides Tracer ApplicationsThickness GaugingRadioisotope Dating Radioisotope Applications in Space Exploration 1.1 The applications are myriadvery small size of radionuclide radia

2、tion sourcesthe great variety of available radionuclidesmedical applicationsindustrial and research applicationseveryday livesdefencethe consumption of isotopes in a country depends on the level of its economic development and industrialization1.2 Stable and Radioactive nuclidesN = # of neutronsZ =

3、# of protonsRadioactive Nuclides:2800Natural: 238U、232Th、226RaMan-made: 239Pu、239Np、131IRadioactivity - 238U radioactive decay seriesRadioactive Series in NatureHave different penetrating ability with materials of different thickness and densitiesKill cellsCause cell mutationIonise moleculesHave the

4、 same chemical properties as non-radioactive isotopes of the same elementIts activity decreases with time2. Production of Radioisotopes ProduceSelect suitable nuclidesRadioactive nucleiNuclear reactoracceleratorgenerator2.1 Nuclear Reactor IrradiationNeutron flux: 10101013cm-2s-1，(n,), (n,p), (n,f),

5、 (n,) (n,)、(n,p): En High, Small，Light nuclides 32S(n,p)32P, 6Li(n,)3H 。 Parent and daughter is different Chemical separation (n,f) Fission products: 500 233U、 235U 、 239Pu decay by emission or by spontaneous fission I 3 7 Cs and 90Sr almost always decay by emission (n,) Parent and daughter are isot

6、ope Chemical separation no low ratio activities ? 2.2 Accelerator ProductionTo produce radioisotopes that are proton rich and that generally decay by positron emission(p,n)、(p,)、(d,n)、(d,2n)、(d,)、(,n)、(,2n) chemical extraction techniques possibleLow yields(n,): （14C：5730a），（19O：26.9s）Accelerator: 25

7、Mg(p,)22Na ，11C、13NNevertheless, is less popular than reactor methodOnly in the cases: High ratio radioactivity chemical extraction possible suitable half lifetime The irradiation of solid materials requires much better beam quality parameters than gas targets. Consequently, beam homogenisation and

8、beam manipulation is needed, ussually not possible at the PET cyclotrons. External beam lines, known from classical isotope production at cyclotrons, will take this function over. The new generation of multi-purpose cyclotrons will be equipped with high-tech diagnostic tools and provide higher beam

9、current than in the past. Production of other useful isotopes with the PET cyclotronProduction of other useful isotopes Auger Therapy20 GBqnatHo (p,n) 165Er10.3 h165ErSPECT10 GBq123Te (p,n) 123I13.2 h123IPET1 GBq124Te (p,n) 124I4.15 d124ITherapy5 GBq186W (p,n) 186Re90.6 h186RePET10 GBq120Te (p,n) 12

10、0I1.35 h120IPET5-10 GBq110Cd (p,n) 110In69.1 m110InPET10 GBq94Mo (p,n) 94Tc4.9 h94TcPET, bioconjugates10 GBq90Zr (p,n) 90Nb14.6 h90NbPET, bioconjugates10 GBq89Y (p,n) 89Zr78.4 h89ZrPET, bioconjugates5-10 GBq86Sr (p,n) 86Y14.7 h86YGenerator, SPECT0.5-1 GBq82Kr (p,2n) 81Rb4.58 h81Rb/81mKrPET2 GBq76Se

11、(p,n) 76Br16 h76BrPET10 GBq66Zn (p,n) 66Ga9.4 h66Gatherapy, bioconjugates10-20 GBq70Zn (p,a) 67Cu61.9 h67CuPET & therapy, 40 GBq64Ni (p,n) 64Cu12.7 h64CuPET, encymes, vitamines0.5-1 GBqnatFe (p,2n) 55Co17.54 h55CoPET: bioconjugates10-20 GBqnat.Sc (p,n) 45Ti3.08 h45TiApplicationBatch sizeReactionT 1/

12、2IsotopeAuger Therapy40 GBqnatHo (p,n) 165Er10.3 h165ErSPECT20 GBq123Te (p,n) 123I13.2 h123IPET2 GBq124Te (p,n) 124I4.15 d124ITherapy20 GBq186W (p,n) 186Re90.6 h186RePET10 GBq120Te (p,n) 120I1.35 h120IPET20 GBq110Cd (p,n) 110In69.1 m110InPET20 GBq94Mo (p,n) 94Tc4.9 h94TcPET, bioconjugates20 GBq90Zr

13、(p,n) 90Nb14.6 h90NbPET, bioconjugates20 GBq89Y (p,n) 89Zr78.4 h89ZrPET, bioconjugates50 GBq86Sr (p,n) 86Y14.7 h86YGenerator, SPECT20 GBq82Kr (p,2n) 81Rb4.58 h81Rb/81mKrPET10 GBq76Se (p,n) 76Br16 h76BrPET50GBq66Zn (p,n) 66Ga9.4 h66Gatherapy, bioconjugates50 GBq70Zn (p,a) 67Cu61.9 h67CuPET & therapy,

14、 100 GBq64Ni (p,n) 64Cu12.7 h64CuPET, encymes, vitamines50 GBqnatFe (p,2n) 55Co17.54 h55CoPET: bioconjugates100 GBqnat.Sc (p,n) 45Ti3.08 h45TiApplicationBatch sizeReactionT 1/2Isotopewith 20 MeV proton induced reactions2.3 Principles of a Generator The use of short-lived radionuclides has grown cons

15、iderably, because larger dosages of these radionuclides can be administered to the patient with only minimal radiation dose and produce excellent image quality. A generator is constructed on the principle of the decay-growth relationship between a long-lived parent radionuclide and its short-lived d

16、aughter radionuclideThree Component Decay ChainsDaughter Decays Faster than the ParentI 2,daughters decay rate is limited by the decay rate of the parent.Important Radionuclide Generators99Mo99mTc Generator:- The 99Mo radionuclide has a half-life of 66 hr and decays by emission. The radionuclide 99m

17、Tc has a half-life of 6 hr and decays to 99Tc by isomeric transition of 140 keV. The extreme usefulness of this generator is due to the excellent radiation characteristics of 99mTc, namely its 6-hr half-life, very little electron emission, and a high yield of 140-keV rays (90%), which are nearly ide

18、al for the current generation of imaging devices in nuclear medicineThe chemical property of the daughter nuclide must be distinctly deferent from that of the parent nuclide so that the former can be readily separated. In a generator, basically a long-lived parent nuclide is allowed to decay to its

19、short-lived daughter nuclide and the latter is then chemically separated. The importance of radionuclide generators lies in the fact that they are easily transportable and serve as sources of short-lived radionuclides in institutions far from the site of a cyclotron or reactor facility.The column is

20、 filled with adsorbent material such as alumina(氧化鋁）, on which the parent nuclide is adsorbed.the daughter activity is eluted in a carrier free state with an appropriate solvent, leaving the parent on the column.After elution, the daughter activity starts to grow again in the column until an equilib

21、rium is reached; the elution of activity can be made repeatedly. the 99mTc is milked from the 90Mo cow.Production timeAs long as possible?Desirable properties of radionuclide generatorshould be simple, convenient, rapid to use, and give a high yield of the daughter nuclide repeatedly and reproducibl

22、y.It should be properly shielded to minimize radiation exposure, and sturdy and compact for shipping. The generator eluate should be free from the parent radionuclide and the adsorbent material.Other extraneous radioactive contaminants should be absent in the eluate.must be sterile and pyrogen-free.

23、 Elution or milking of the generator is also carried out under-aseptic-conditionsRadioisotope Processingisotope extraction,separation purification 2009 QSA 9 Global Incseparation, purification, containmentwaste reduction, solidification, disposal2.4 Production requirementskeep the radiation dose to

24、the patient as low as possible. generally have a short half life and emit only gamma-rays preferred.From an energy point of view, not be so low not too high : 100 and 200 keV. needs to be incorporated into some form of radiopharmaceuticale capable of being produced in a form which is amenable to che

25、mical, pharmaceutical and sterile-processing. GMP (Good Manufacture Practice for drugs) Chapter 8. Radioactive isotopes and Their Applications Introduction Production of Radioisotopes Some Commonly Used Radioisotopes Tracer ApplicationsThickness GaugingRadioisotope Dating Radioisotope Applications i

26、n Space Exploration 39K (93.2%)59Co 88Sr127I133Cs一些放射性同位素40K 1.28x108 a60Co 5.27 a90Sr 28.8 a131I 8.04 d 137Cs 30.12 aSome Radioisotopes Used in Nuclear MedicineSyntheses of Radioactive IsotopesOver 1300 radioactive nuclides have been made by nuclear reactions. The most well known is the production

27、of 60Co, by neutron capture,59Co (100%) (n, g) 60mCo and 60Co - b and g emission t1/2 = 5.24 yThe sodium isotope for study of Na transport and hypertension is produced by23Na (n, g) 24Na (b emission, t1/2 = 15 h)For radioimmunoassay, 131I is prepared by127I (n, ) 128I (b+, b- EC, t1/2 = 25 m)There a

28、re many other production methods.Syntheses of Transuranium ElementsFrom 1940 to 1962, about 11 radioactive transuranium elements (almost 100 nuclides) have been synthesized, about one every two years. Representative isotopes of the 11 elements are neptunium (Np93), plutonium (Pu94), americium (Am95)

29、, curium (Cm96), berklium (Bk97), californium (Cf98), einsteinium (Es99), fermium (Fm100), mendelevium (Md101), nobelium (No102), and lawrencium (Lw103).La57 , Ce, Pr59, Nd, Pm61, Sm, Eu63 , Gd, Tb65 , Dy, Ho67, Er, Tm69, Yb, Lu71Ac89, Th, Pa91, U92, Np93 , Pu , Am95, Cm, Bk97, Cf, Es99, Fm, Md, No,

30、 Lw103Among these, tons of 239Np, and its decay products 239Pu have been made for weapon and reactor fuel. Successive neutron capture reactions are major methods, but accelerators are involved. . . Syntheses of Transuranium Elements -continueVery heavy elements are synthesized using accelerated nucl

31、ides,246Cm + 12C 254No102 + 4 n,252Cf + 10B 247Lw103 + 5 n,252Cf + 11B 247Lw103 + 6 n.These syntheses completed the analogous of rare-earth elements. These elements were made during the cold warChapter 8. Radioactive isotopes and Their Applications Introduction Production of Radioisotopes Some Commo

32、nly Used Radionuclides Tracer Applications Thickness GaugingRadioisotope Dating Radioisotope Applications in Space Exploration 4.1 Radioisotopes are ideal tracersThe use of some easily detected material to tag or label some bulk material allows the bulk material to be followed as it moves through so

33、me complex process.Fluorescent dyes, stable isotopes, radioisotopes Why radioisotopes? The amount of tagging material neededIf a sample contains N atoms of the radionuclide, the observed count rate (CR) is: detection efficiencyTo detect the presence of the radionuclide tag, this count rate must be g

34、reater than some minimum count rate CRmin which is above the background count rate.Then the minimum number of radioactive atoms in the sample needed to detect thepresence of the radionuclide isIf the atomic weight of the radionuclide is A, the minimum mass of radionuclidesin the sample isA typically

35、 gamma-ray detector efficiency is 0.1 and a minimum count rate is CRmin 30 min-1 = 0.5 s-1 Thus, for 14C (T1/2 = 5730 y = 1.18 x 1011 s), the minimum detectable mass of 14C in a sample is:few atoms are needed!How about 32P (T1/2 = 14.26 d) ?P is often used in plant studies to follow the uptake of ph

36、osphorus by plants.374.2 Medical Applications Radioisotopes with short half-lives are used in nuclear medicine becausethey have the same chemistry in the body as the nonradioactive atoms.in the organs of the body, they give off radiation that exposes a photographic plate (scan) giving an image of an

37、 organ.Thyroid scan 4.3 Leak DetectionTo find the location of a leak in a shallowly buriedpipe without excavationThis use of radionuclide tracers to find leaks or flow paths has wide applications:finding the location of leaks in oil-well casings, determining the tightness of abandoned slate quarries

38、 for the temporary storage of oil, Locating the positions of freon leaks in refrigeration coils, finding leaks in heat exchanger piping, locating leaks in engine seals.Underground pipe leaksTracer will be added to the liquid in the pipeDetector is moved along the pipeThe count rate will increase as

39、there is large amount of waterThe radioactive source will be a short half-life emitter4.4 Other applicationsPipeline Interfaces Flow PatternsFlow Rate MeasurementsSurface Temperature MeasurementsOil from different producers is often carried in the same pipeline.measuring the spatial distribution of

40、the activity concentration(1) ocean current movements, (2) atmospheric dispersion of airborne pollutants, (3) flow of glass lubricants in the hot extrusion of stainless steel, (4) dispersion of sand along beaches, (5) mixing of pollutant discharges into receiving bodies or water, and (6) gas flow th

41、rough a complex filtration system.measurements of the activity concentrations of a radioactive tag in the fluid mediumThe time required for the radionuclide (and the flowing material) to travel to a downstream location is given by the time for the activity to reach a maximum at the downstream locati

42、on.krypton atoms are only released at certain high temperatures. remaining 85Krkryptonated surfaceThickness gauging by radiation transmissionThickness gauging bybackscatter transmission5. Thickness gauging Thickness gauging usingstimulated fluorescenceThickness controlThe manufacture of aluminium fo

43、il emitter is placed above the foil and a detector below itSome particle will penetrate the foil and the amount of radiation is monitored by the computerThe computer will send a signal to the roller to make the gap smaller or bigger based on the count rateChapter 8. Radioactive isotopes and Their Ap

44、plications Introduction Production of Radioisotopes Some Commonly Used Radionuclides Tracer Applications Thickness gaugingRadioisotope Dating Radioisotope Applications in Space Exploration Carbon datingCarbon has 3 isotopes:12C stable13C stable12C:13C = 98.89 : 1.1114C radioactiveAbundance: 6.1 Radi

45、ocarbon dating principlesBy observing how much of a long-lived naturally occurring radionuclide in a samplehas decayed, it is possible to infer the age of the sample.Radiocarbon Forms: in the upper atmosphereDecays:t = 5730 yr.Living Tissue14C/12C, Tissue ratio same as atmospheric ratioDead Tissue14

46、C/12C14C/12CtissueatmosphereMeasuredConstantCalculated?Clock starts when one diesN ( t ) = N(0)exp(-t)we never know N(0).the initial ratio N(0)/NS of the radionuclide and some stable isotope of the same element can be estimated with reliabilityThis ratio also decays with the same radioactive decayla

47、w as the radionuclideIt is usually easier to measurethe specific activity of 14C in a sample, i.e., A14 per gram of carbonan initialWhat is the age of an archaeological sample of charcoal from an ancient fire that has a A14(t)/g(C) ratio of 1.2 pCi/g of carbon? Radiocarbon Measurements and Reporting

48、 Radiocarbon dates are determined by measuring the ratio of 14C to 12C in a sample, relative to a standard, usually in an accelerator mass spectrometer.standard = oxalic acid that represents activity of 1890 wood14C ages are reported as “14C years BP”, where BP is 1950First 14C date: wood from tomb

49、of Zoser (Djoser), 3rd Dynasty Egyptian king (July 12, 1948).Historic age: 465075 BPRadiocarbon age: 3979350 BP Second 14C date: wood from Hellenistic coffin Historic age: 2300200 BPRadiocarbon age: (C-?) Modern! Fake!First “Curve of Knowns”:6 data points (using seven samples) spanning AD 600 to 270

50、0 BC.Half life used: 5720 47 yearsCarbon-14 dating lends itself to age determination of carbon-containing objects that are between 1,000 and 40,000 years old51The Shroud of TurinCredit: The Image WorksReputed as the burial cloth of Jesus Christ. C-14 dating by 3 independent labs report the Cloth ori

51、ginated during the Medieval times, between A.D. 1260-1390.52Mummified remains found frozen in the Italian AlpsAt least 5000 years oldBy carbon-14 datingIn 1991,hikers discovered the body of a prehistoric hunter that had been entombed in glacial ice until the ice recently moved and melted.Pathologist

52、s（病理學(xué)家） also examined his well-preserved remains, he died from a fatal wound in the backmost likely delivered during his prolonged struggle with at least two other prehistoric hunters.data from:corals (bright red)lake varves (green)marine varves (blue)Speleothems （洞穴堆積物(如鐘乳石)） (orange)tree rings (bl

53、ack)The Radiocarbon Calibration Curve (atmospheric 14C history) Principle: compare radiocarbon dates with independent dates Examples of independent dating: tree-ring counting, coral dates, varve counting, correlation of climate signals in varves with ice coreHughen et al., 2004equilineObservation:ra

54、diocarbon datesare consistently younger than calendar agestimeSource of Error in 14C datingVariations in geomagnetic flux. Geomagnetic field strength partly controls 14C production in the atmosphere because of attenuation affects on the cosmic flux with increasing magnetic field strength. Modulation

55、 of the cosmic-ray flux by increased solar activity (e.g., solar flares) leads to attenuation of the cosmic-ray flux.Influence of the ocean reservoir. Any change in exchange rate between ocean reservoir and atmospheric reservoir will affect the level of 14C in the atmosphere.Industrial revolution (r

56、atio of 14C to stable carbon decreased because of burning fossil fuels) and bomb effects (14C to stable carbon increased because of increased neutron production from detonation of nuclear bombs in the atmosphere) have made modern organic samples unsuitable for as reference samples. Radioactive elementsNot all elements are radioactive. Those are the most useful for geologic dating are:U-238Half-life = 4.5 ByK-40Half-life = 1.25 ByAlso, Sm-147, Rb 87, Th-232, U-235The blocking temperature is the temperature above which a mineral or roc