CA2261444A1 - Method for making iodine-125 loaded substrates for use in radioactive sources - Google Patents
Method for making iodine-125 loaded substrates for use in radioactive sources Download PDFInfo
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- CA2261444A1 CA2261444A1 CA 2261444 CA2261444A CA2261444A1 CA 2261444 A1 CA2261444 A1 CA 2261444A1 CA 2261444 CA2261444 CA 2261444 CA 2261444 A CA2261444 A CA 2261444A CA 2261444 A1 CA2261444 A1 CA 2261444A1
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
- G21G4/00—Radioactive sources
- G21G4/04—Radioactive sources other than neutron sources
- G21G4/06—Radioactive sources other than neutron sources characterised by constructional features
- G21G4/08—Radioactive sources other than neutron sources characterised by constructional features specially adapted for medical application
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
- G21G1/00—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes
- G21G1/02—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes in nuclear reactors
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Abstract
A dry-process method for producing iodine-125 loaded substrate particles for use in radioactive sources including the steps of providing a plurality of substrate particles, contacting the substrate particles with xenon-125 in gaseous form during the radioactive decay of the xenon-125, and the substrate particles retaining iodine-125 generated by the radioactive decay of the xenon-125.
Description
METHOD FOR MANYNG IODII~E~lZS LOADED SUE$TRAT$9 FO~t U$E xN RADrdAGTIV$ SOURCES
9ACKGROQND 01~' '~8 INV~TTON
The preoent invention relates to a method nor a~aklng iodine-1~5 loe~d~ad substrates for use inn radioacti.ve avurcee~. ~ Kore particularly, tt~a present invention relateo to a dty,pracsms ~aethod sar producing iodine-Za5 loadod zeelite particles for use in sealed braebytherapy souxces.
For decades, the usual method of commercially prodacl.ng lodinewla5 ha~ involved the irradiation of xenoh gas with thermal neutron~ it $ nualaat reactox. The nuclear rvactian e~loyed is written as xenon~124(n,ga~nma)xenon-izs-~i.odine-1z5. the xenon gas taurget is a~ually enriched in the stable isotope xenon-1~4 end ig ihradi,ated for about I duty in a container placed near or 0 ~rithfn a reactor core. The g8s is than xemaved from the irradiation eortaiper, usually by cryogenic pumping, to a rem,ota vessel Vhere it is held to decay nor a period v! 1 to 9 dnya_ During this perl.vd, radioactive xenon-Iz5 (ba~,p~life J,~ hours) lvt~ted during the irradiation decey$ to form iodi,ne~125 (half-liPe 60 days). The iodine-1~5 migrates to the decay vespel eaZls, to w~t~ioh it adhQrea gaits ~l.rnly wlthough through poorly undere~tood ~neahahisma. At the end of the decay period, the xenon Qae ie pumped e.ray to be re~irradiated. The cycle mey ~
repeate6 many ti~nee to build up t?re required amount o= iodine-laS
i.ty the Qecay weasel. ~'he ivdine~l2s is then removed lrob the decry vessel either by high temperature volatilisation ana entrapment or the raGloiodi.ne vapor in an dlkallne solution, or Ay directly applying do alkaline avlution to the interior o! the decay veegnl~ washing the walls of the vassal, end than xaeowrlrig the solution. tn either case) the prima=y prodttat ie an alkaline solution usually containing iodine-128 ~rith a conoehtration 3n the ratsge 0.5 to 1 auriea per millilf.tar.
In co~amercinl iodine-1Z5 radioactive svWrce praduativn, eubotratss loaded with iodine-!Z5 are hermvtioal.ly aoaled in aapeules. !lost a! this activ~.ty is i.n cvtlhactian with brachytherapy swats~e. Th~ase are encapmu~lntsd e~ourcos with substrates holding iodine-18S ssgled inside welded cylindrical titanium aapeules. The teartnologies underiyiag iodine-1Z5 brechytherapy douroes era a~ariaAd in U.B. Patent tros.
3,751,0a8; a,323,055; 4,891,i65; and 4,99d,013) which patents are ir~corpvra~ted horein bY referenen.
Currently, the substrate preparation procasaeA involve the handling, dispensing end evaporation o= aguevus voluticns '.e oontaining iodine-125 in high Concentrativh, such as the aolutiona prepares bY the general method far iodine-i25 r, production dpperibed above. It ie generally hot practical to carry out tsese solution operations in permanently sealed Systems at~d they always present a pubstantial radiological har~trd because of rvl~aaas to the working environment of volatile radioactive iodine species such as elemental iodine (1~5Z~) and _2_ hydrogen l0dida (H1~6I~. Thees volatile radioiodinee are initially generated in solution by reactivna between the iodine-125 in the iodi.dr~ ion Zor~f~ and chemically reactive speciev such t~s t~rdrogen and o~cygen radicals, free electrons, and hy4tog~en peroxide produced in the solution by the rediolytia daeompositi~
of water. Much e!lott and cepital inveatmQnt are spent ih guarding against and coping with such rele4oea.
suHMARY of Trcs r~vESrT=oN
zn aceordenc. with a broad aapact of the present invention, there is providedl a dry~prvcesa method far proeucin~t iodine-125 108dod aVbBtrate particles for use in radioactive svurcoa. Tha metbvd comprises prvvid~,ng a plurality of gubstrate..p4rtielas) end aontectihg the substreto particlem with x8nvn-izs In gaseous form during the radioaotlve decay or the xenan~las. The subotrate partiolta retain 1,o41ne~1,2s generated by the radivacCive Qecar of the xenon-125.
In accordance with a more specific aspect of thv prosent invention, thrre is provided a d;y-process method of producing oub~trate partic148 loaded with tightly bound i,od.ine-z25 !or use aG ae the active components vt sealed radioactive sources.
rn accordance with another specific aopeat of the invention, t~
there ie provided a method for making a plurality of iodine-Z25 loaded aubstrateB comprising the steps of providing a gourca of xenvn~l25 in s cold trap; adding the pluraaity of pubstre~toe td a decay vesoai~ mnd cvollng the decay vessel to reduce the tempere~ture of the subetrete particles For improving xenon gee absorption efriciency of the substrates. The cold trap and the decay vessel are interconneoted, atl4 the oold trap ie waxmed to cause the xenon-lZ5 tv expand in a gaseous state into the decay vessel. For n predetermindd period vt time, rgdioactive decay of the xenon-1z5 to iodine-lz5 i~ permfttad vhiio ire the gaseous otatm ar'd in contact with the eub~trate particl~aa, with the iodine-1~5 being retained by the substrata particles. Tbie pr~sdetermined p~riod of tie ig in keeping With th,o hall-file of xandn~i25, i.er., typically 10 to loo hours. The cold trap and thm 4ecay vesool are diaoonnected; and then tho iodine-125 loaded substrate p~trticlas ert reatoved. f=ore the decay veasei.
In contrast to cur7rent technology, the invention has the following advantages. It avoids the ~xaking and handling of radioiodine solutions at the roactor site, the dispensing and evaporation o! redioivdine solutions nt the radioactive source manulacturidg Dtte) and tho aeaoaiat~ad ra4iologicel hadatrds and costs at both aites.~ The invention also pravidea source substrates ~ohich are very uniform is their radioactivity content relative to sub~tratea prepared by other ~nethoda.
A broad object of the invontion is to provide.subetrxtes bearing iodine-1~5 for use in sealed radioactive sources by a method that le radiologicaily safer and less costly than current methods.
Another broad object of the invention ie to proviso a m~thoa of making iodine-1Z5 b~aring sobstratas for use in sealed radioactive sources ehnt are more consistent ~oi,thin a batch in _4 _ their radioactivity content than those made by vther.aec.hode.
another broad object of the invention is to provi9e subetrotva bearing iodi»4~i25 for ua~e in raQiodctive eouroae by meano of a 4ry process in a seraled ay~tem uhieh Qoe6 not involve rediaawtiva iodine so7.utiong.
A ep~oiric object o1 the invention is to provldo a t~st?~od of inking $eoliea substrates bearing iodine-iz5 Poor use in sealed brarhytherapy sources and other types oP sealed radioactive 6all~,'C~~ .
IQ BRIEF DESCArP'i'IGM OF THE DRJI~PIHO
The Figure ~ia a schematic draorirrg o! a xeno» gas hattaling Byetem connected to a~ xenon irradiation ahanfber in the core o! a nvcloar reactor and tv m decay ve8pel cor~ta~ining substrate pnrtiolar.
DESCRIPTION OF THE PREF$RRED E~ODIM~?iT8 zn principle, the ob7eate~ of the invention are~~aehlavpd through assns of absorbing and holding xanvn gas at low t~mperaturo within partiel~a of a Suitable substrate n~ateriii.
Ths xe»on gas must contain a suitable concentration of ~o tsdioadtiye xenon--1~~ ~rhich decays tv a Buitnble amount of iodine-1z5. The decay of the xenon~iZ5 xuet~,tdke place at temperatures above the xenon boiling point eo that the xenon~x~5 remains in the gag phase a»d consequently the generated lodi»e-1~5 is urii~ormly distributed throughout the absorbing aubetra.te masm. Tha substrate material at room temperature must later tis~ly retain the iodine-lzs produced from the decay o~ the xenon~125 but not iretairi the xenon gaa.
-s-Zaolitee~art the prolezred substrate meterietl. Zeolftes are a olaae of crystalline molecular s3evea that occur naturally or oan be eynthesisad irt powder lorn~. 2~hny are otable inorganic cvmpounde~ that have open a lumano ~ s i 1 ice to Fra~tewarke that a l.l.oWg thaw to hoot ether che~nieal epeele~'within their gtrueturae.
Zaalita~~e arc uped in large quancitiee in sang industrial appl3eationa. comprehenelve inlorraation oat $eolit~e is given in the textbook 'Zeolite Molecular SSeveB' by bonald p. Hreclc, John Wiley dad Sons Irc., New York (i974), vhiah is incorporated herein by rei~rence.
Zlolitas have sxaollent properties for use as substrate materials in radi0llctive aourcee. The relsvaht prvpsxtias of zeolitee in this regard include good heat ana radiation resistance, eativn sxehange capaoities comparable with organic xoaine, good capacity tvr th~ edaorptivn and retsntien of radiosctive iodine, low density and average atvmie number of elemental certstituenta weansr~q loo attenuation or lvv-energy photons, and with a binder ran be formed into durable pellots~ or spherical beads iri appropriate sizes.
ao In a preferred embodit~eat, the substrate partiolQS~ are driod gevlit~ molecular sieve particles, prelerabZ~ spheres, that beve been silver-doped by catl0~i ~xchdnga are employed ea the gub9~trato material. 1~ e~aalJ~ metal vo~esl lilted with the zeolite spheres is atts~Ched tv a eetiled gas handling syst~ and ovacuata~d through a valve on th~ ve~sel.. The vessel and zeolite spheres aro then Cooled to abc~Vt -75aC by imaersion v! the vessel in mol~.d carbon dioxlda powder (dry iced. The e.ctual dry foe sublimation tearperature at standard (atmospheric) pressure ie -78.5°c. The cold taolite sphere mass is pertused pith a volume of xenon ges3 highly enriohed in the stable isotope xenon~124.
The xenon gar ha~ bean just prsvicuely irradiated with neutrons in b nuclear reactor and contains a suitable anvunt of radioactive xenon-lZ5 farmed 9uring the irradl.atioh via th0 , nuclear reaotivh xenon-lZd (n.gs~mr5) xenon~la5. Most of the xersah-la5 (half-li!~ l7 hours) is allov4d to decay to ~.odirte-12S (hsilt-lifo 60 days) whilst in contact with the xeolits spheres. The iodine~1~5 so permed is entrapped within the eovllte Btrvaturg or becomms chetsically bauOd with the silver dapant in the spherms.
Ins either casA thA iodine-l25 remains rirmiy e~ttaabe~d to the eeolite spheres vhsn) after a suits~ble deoay period, the vessel) and ~eolite ~phsreg are returned to room temperature and the xenon gas ~.e pumped away to ba re-irradiated in the reacto;. The cycle may be repeated a number of tiasss4 until the~ arvunt of iodine-Z~S ors t~ho saolite spheres reaches the desired levAl o!
rad~,oaativitY. The olos~ed vassal vorstaining the s;eolite spheres may then be subjected to a heat treatment to t~rther s~tabiliae o the adherence Cr the iodine-1~5 to the s3pherwr. Thnn~the evacuated vessel, with its valve closed and containing the reol~te l~phsres, is re~eoved free the gas handling sygt~a. The apherae are removed from the v~sasel and may be ured withcvt i'urther treatstent as radioactive substrates it radioactive sources. .
Opti4nally at this stage, the zeolite apher4m xith bdeorbed iodinG~laS may be heated to the tanperature et which the sreolite etruotura collapses and vitrification oacurg. Tha vitri.=ication tampargture for pellitizeC zeoZitve is typically ih tho range vi trOtO about Aoo°C to aba~ut l~OV°C, vitrl,tication results in hat'd glassy spheres Chat are smaller than ths~ originals $r~d that have arihanced propsstigs Eor certain appliCat~-, ~n particular, mechanical axrahgth is i~aproved and tha potantiex tvr abrasion of radioactlvs material from the ~aur=nc~ With attendant radiological haaard is r~duced. The potential fen tha leaching of redioactiva material from the sphorea is also reduced. Thi~ ie important in io applications involving contact With liquids, and is of particulaz importance in connection With implanted braehythera,py s~ouraee olhere a bleak in the eneapeulativn ef A source arould oxpvev ~e spheres to body lluids.
Xenon gas ran be strongly absoxbed by certain types of soolitss at low te~iperature~. Romssrkably, 1 gram at either 4A nr 13X seolite at about -~ovc, rrhicri ie well above the xenon boiling point, will bbevrlo ovor 5o milliistars of xenon gas, 2'Aia is a vo~equerce of the special properties of seolit~ae; t?~e xenon gas btoms are clvse~packad into the zeolite cryetel lattice almost in ao s l.lc~uid phaaA. Zeolitee, when doprd with metallic eiesasnts such as sllvor, are v~rY erfective in aeqvestsring nearly vhaniaal i~
species of iodine from offlnsnt gas atreasv. Inrosmativn to this ettedt is given in the thosts "Zaolites as scavengers for Radioiodine 8peciea from the gas Phaee" by c.h. sa~apson and the references therein. This thesis is incorparatad herein by relerence.
filth ='~tere=tce tv the l~S.gure, ~ar~e is shov~n an operit~ng _8 _ nuclear reactor core il vhcrein is located a xenon gas target ohs~nber 1a connected via valves and tubing to an evacuateG xenon gee hanQlir~q system l0. All of the valves on the eyet4m gxA
closed. The target chamber cont~eine high-pu..tity xenon ga~o erf.riched in the sta~ole isotope xenon-~.2~. Tn~r target qaa is ixra4lated yith neutxons so that some vt the xenon-1z4 nuclei capture a neutron anc~ becotoe radioactive xenvn~t2s nuclei . l~tte~-a euitaDle i,xrediation period that e~xlowe p~yfficient build-up of xenon-»5 radioe~ctivity, a~ually about 1 day, valves ~ vi end V~
1,0 ere opeud~ and the xenon target gas end generated xenon-lZ5 are cryo-pumped to a sold trap i3. This is acavmplieh4d by cooling the cold trap ~rith liqu3.d nitrogon and theroby reduc~.ng the vapor pre~sure of xenon Co essentially eero by freeaing it to the solid state. During'the cryo-pwnping opCtation, the IImal1 dacxy vessel 14, previously f~lll~d vith suitable absorbing ~ubetrate ~rartidles 15, and puaped out using the vacuum pump ls, i$ immersed in a guite~ble oold medium so as to reduce the temperature of the suDatrate particles to betW~~n about -70°C and about -80°c to thereby attain good xenon gas absorption vilicienay. valve vz is :a thQn cloned and valve V3 eepaxating tho cold trap troe the decay ve,sael and valve V4 on the devay vsesel era opened. The cold trap 13 is v~atmed to room temperature allowing the frosen solid xenon to return to the gab phase ahd to expand into the deCBy vessel l4 ana~re it is Wrifvrmiy absorbed by the oold substrate particles. Ve,lve Vd is theil closed. The cold medium ~,g bristly removed tro~n around tl~e dece~y v~ssel 1~4 in ordef to faci7.itate an accurate meeauresent o! the amount of xenon-~z5 radioactivitx in .,g_ eonte~ct With Lhe substrata particleB by se8ns or 4 rbdiativn detaotor 1'~ .
With valves V3, V4 and V7 closod, valves V5, V6.and V8 are opened to a~.lov n fresh cb~xrge of xenon target gas to ilv~r from the storage ve~oeel is into th4 qae target chnmbe: La for irradiation. Ve~lve V1 iB then closed and valves v2 and V3 ate opened. ~,'ho lines are Gryo-pumped free vt xerian by temporarily imtaereing 4 cold rings= 19 of the storage vvseal 18 itt liquid ~1i'ttogen. A11 peen valves are then CIOged. After a eui~table 1o daoay period, usually 1 to 3 de~yo, during which rise the decay vessel 14 ie cvntiruouslY kept Geld at a temperelture batweer~
about -~o°e and about -eo°c in vrc~er to minimize the internal gag pressure) the sold finger ~9 0! the atoxage vessel 18 is again te~tporari7,y avcled with liquid nitrogen to a temperature between about -190dC and about --t00°C. V~tlvos V4 and V5 are opelloc3, and the sold medium ie removed l=am around the decay ve8sel. ThH
xenon t?fan fldwu from the decay vesoel ~4 to the atorege vegsai 1A loavlng the iod,ine~laS behind oe the substrate p~rt:lClms.
Then all open vAlvas Ore clocsd. The cycle taay be repeated to gild up the enovrtt of iodine-125 vn the substrate particles.
then the substrate particles 15 mre eutEicle~ltly loaded With iodine--185 and any xenon has been pumped array, xhe eiosed inn evacuated decay vassal z4 and substrate particles l5 may be hAatod to a tempart~ture betveen about loo°c and about aOOnC to chetaically gtabiliae the iodino~125, nrd then cooled to a tempexa,ture batt~ean about 10°c and about 30°c and pumped upon for a short period to re~o~e a~~y iodlina-1a5 l~tt ire the vapor pheso.
~10-The decay-veeael 14 ig valued closed, disconnected at ~o frara the gee handling eysteea 10 and ret~cved tv s ventilated le~aiiity fox =urther handling. The nearly radloaictiva ~ubstra~te particles 15 are thon romovad lros the decay vasbei ld and eaa~pled for quality assurance taste prior to being available for further proaessi.ng such as vitrification or ivr vsa in radioactive evurooa.
It vih be reeocpnized that the system depicted 1n the Figgie is a ai.rplo one. In practice, multiple decay veaoel8 to hold io substrate particles) and even multiplo reactor gas~target chdmbero xay ba installed to add flexibility and capacity tv the sxstem.
Ih a preferred embcdi,mcnt of the a~athod described adova) the substrate particles are zaolite spherer sop~a oritn silver by nation exchange and meant primarily !or use in brachythorapy oourcae) the xenon target gag is enxiched to over 50 p~r cent in the xenon~124 stable ievtopo, and the cold medium is aolid carbon dioxide (dry i~co).
PRGPI~ir't'IC EXAMPLE
o A 5o milliliter volume or x~non gas onriahed to over 99 per cant in xenon-1~4 ie irradiatmB in a nuciea~r~,roactor for Z4 hours at a tDermal neutron flux of 5 x 10i3 nautrone pot square dar~tiatetar pex second. fhe amount of xenon-12s (half-life 17 hoys'a) produced et the end of the ~.rradiation i.s approximately coo ourieo .
At the end of the irradiation, the xenon gas i.s tranglerred to a small decay veaael containing io,oov silver doped type ~3X
~11-~eolita mpherical beode cooled tv approximately -~3°c with dry ice. The decay ves8al is then valves closed, and kept cool With dry ice except fox a period of about 1 minute at the beginning xhen the dry ice ie~ xeaiovesd ao Chat an acottxate radia~tiori reading of the deoay vea~sel c4n be taken. The total internal volume et the 9Qcay vessel ie 1 to 2 billilitors. The dl,ameter of aach zevl3te bead is o.65 m,illf.motars and the i.o,0o0 beads essentially fill the decay vessel. Nearly all o! the rerun is abmorbed end the gee p=eoeute inside the decay va9ael is les8 than 1 atao~phare.
lifter a ?~ hour decay periell, the xonvn is punpea away to a 8torsg~ vessel.. 11t this stagy there ie a total. of appraximat~ely Z.s curies oP iodibe-ia5 on the zeolite bead substrates, or aDOut 0.15 millicuriea per bead, xt is intendod to produce brachythorapy sources containing two beads each end having redioactsv~,ty cvnt~ts of 7..0 miilicuries each. Tt~e irxadiatiors/deeay cycle is therefore repeated ~ sore times over the next nine day8, whereupon, allawfng for ~aome decay during trie proce~ea) each bead has slightly in exces8 0! 0.5 fii111aur~,es of 2o iodine~la5 which ie oufficietlt to make too-ba~,d ~ouroQe co~ta~iniag z miliicu~cie per source. (Note t~rat the 24 hour xenon irradiation period associated with a partioular eycxe vvmme»eeg 48 Z'IOIlTg into the 71 hour decay period of the previova cycle).
The beadg are transferred from the decay vesse~. into a quartt vial that is then flame healed. The rtv;artz vial is placed in a lurnace at zoom temperature. The furnace is turned on and ov~r a period of one hauz~ the Ylal ana beads ere heated to ~lZ-l000°C. In this psocosa, there ~.s no loss of iodine-iZS) but the beads are vitrified and ~ceduoed in diameter by about z5 I,~er cent.
The bea4e aQhexs to each other very slightly. but upon cooling they are easily separable by shaking and are ready for uas fn radioaCtivs sources. -other pvrou8 materi$,lo, such as charaoai particles) possess otrong xenon absorption and iodine retention properties and may be substituted ror the prslezrad ieel3ts aubet~rats particles.
certain non-porous end noh-absorbing substrata Aateri.als with surfaces having affinity ~o~ iodin~, such as ai7.ver wires) may be substituted for the pseterrod $avlita substtato particles.
although in this case, because there ie no xenon gee pressure reduction by absorption, decay vessels capable of sustaining internal gas preosures of s~verai tone a! atmospheres would be required. Also xenon-iss may ba produced by ~oaang of a charged particle accelerator, ratter than a reactor, by irradl.ating a.
xenon gas target oontairiing et0ble xenon-~ia~ with protdne. All of the~a modifieationa are co~tnmplated and enaaapasoed by the invention. 111eo, the vitrification process ~aay be used for ~4 aeolites bearing other radioisotopes such as palladium-lo3 and ytterbium-l69.
Although the invention has been described in conjunction with epaeitic embvaiments, it is evid~ant that many alternative$
and variations dill be apparent to those sxillaa in the art in light at the foregoing deeeri.ptier. Accordingly, the invet~tlor ie i,ntsnded to embracs a11 of the alternatives arid variations that fall within the spirit end scope of the eppnnded claims.
The above references are hereby incorporated by refer~nae.
Vl~
9ACKGROQND 01~' '~8 INV~TTON
The preoent invention relates to a method nor a~aklng iodine-1~5 loe~d~ad substrates for use inn radioacti.ve avurcee~. ~ Kore particularly, tt~a present invention relateo to a dty,pracsms ~aethod sar producing iodine-Za5 loadod zeelite particles for use in sealed braebytherapy souxces.
For decades, the usual method of commercially prodacl.ng lodinewla5 ha~ involved the irradiation of xenoh gas with thermal neutron~ it $ nualaat reactox. The nuclear rvactian e~loyed is written as xenon~124(n,ga~nma)xenon-izs-~i.odine-1z5. the xenon gas taurget is a~ually enriched in the stable isotope xenon-1~4 end ig ihradi,ated for about I duty in a container placed near or 0 ~rithfn a reactor core. The g8s is than xemaved from the irradiation eortaiper, usually by cryogenic pumping, to a rem,ota vessel Vhere it is held to decay nor a period v! 1 to 9 dnya_ During this perl.vd, radioactive xenon-Iz5 (ba~,p~life J,~ hours) lvt~ted during the irradiation decey$ to form iodi,ne~125 (half-liPe 60 days). The iodine-1~5 migrates to the decay vespel eaZls, to w~t~ioh it adhQrea gaits ~l.rnly wlthough through poorly undere~tood ~neahahisma. At the end of the decay period, the xenon Qae ie pumped e.ray to be re~irradiated. The cycle mey ~
repeate6 many ti~nee to build up t?re required amount o= iodine-laS
i.ty the Qecay weasel. ~'he ivdine~l2s is then removed lrob the decry vessel either by high temperature volatilisation ana entrapment or the raGloiodi.ne vapor in an dlkallne solution, or Ay directly applying do alkaline avlution to the interior o! the decay veegnl~ washing the walls of the vassal, end than xaeowrlrig the solution. tn either case) the prima=y prodttat ie an alkaline solution usually containing iodine-128 ~rith a conoehtration 3n the ratsge 0.5 to 1 auriea per millilf.tar.
In co~amercinl iodine-1Z5 radioactive svWrce praduativn, eubotratss loaded with iodine-!Z5 are hermvtioal.ly aoaled in aapeules. !lost a! this activ~.ty is i.n cvtlhactian with brachytherapy swats~e. Th~ase are encapmu~lntsd e~ourcos with substrates holding iodine-18S ssgled inside welded cylindrical titanium aapeules. The teartnologies underiyiag iodine-1Z5 brechytherapy douroes era a~ariaAd in U.B. Patent tros.
3,751,0a8; a,323,055; 4,891,i65; and 4,99d,013) which patents are ir~corpvra~ted horein bY referenen.
Currently, the substrate preparation procasaeA involve the handling, dispensing end evaporation o= aguevus voluticns '.e oontaining iodine-125 in high Concentrativh, such as the aolutiona prepares bY the general method far iodine-i25 r, production dpperibed above. It ie generally hot practical to carry out tsese solution operations in permanently sealed Systems at~d they always present a pubstantial radiological har~trd because of rvl~aaas to the working environment of volatile radioactive iodine species such as elemental iodine (1~5Z~) and _2_ hydrogen l0dida (H1~6I~. Thees volatile radioiodinee are initially generated in solution by reactivna between the iodine-125 in the iodi.dr~ ion Zor~f~ and chemically reactive speciev such t~s t~rdrogen and o~cygen radicals, free electrons, and hy4tog~en peroxide produced in the solution by the rediolytia daeompositi~
of water. Much e!lott and cepital inveatmQnt are spent ih guarding against and coping with such rele4oea.
suHMARY of Trcs r~vESrT=oN
zn aceordenc. with a broad aapact of the present invention, there is providedl a dry~prvcesa method far proeucin~t iodine-125 108dod aVbBtrate particles for use in radioactive svurcoa. Tha metbvd comprises prvvid~,ng a plurality of gubstrate..p4rtielas) end aontectihg the substreto particlem with x8nvn-izs In gaseous form during the radioaotlve decay or the xenan~las. The subotrate partiolta retain 1,o41ne~1,2s generated by the radivacCive Qecar of the xenon-125.
In accordance with a more specific aspect of thv prosent invention, thrre is provided a d;y-process method of producing oub~trate partic148 loaded with tightly bound i,od.ine-z25 !or use aG ae the active components vt sealed radioactive sources.
rn accordance with another specific aopeat of the invention, t~
there ie provided a method for making a plurality of iodine-Z25 loaded aubstrateB comprising the steps of providing a gourca of xenvn~l25 in s cold trap; adding the pluraaity of pubstre~toe td a decay vesoai~ mnd cvollng the decay vessel to reduce the tempere~ture of the subetrete particles For improving xenon gee absorption efriciency of the substrates. The cold trap and the decay vessel are interconneoted, atl4 the oold trap ie waxmed to cause the xenon-lZ5 tv expand in a gaseous state into the decay vessel. For n predetermindd period vt time, rgdioactive decay of the xenon-1z5 to iodine-lz5 i~ permfttad vhiio ire the gaseous otatm ar'd in contact with the eub~trate particl~aa, with the iodine-1~5 being retained by the substrata particles. Tbie pr~sdetermined p~riod of tie ig in keeping With th,o hall-file of xandn~i25, i.er., typically 10 to loo hours. The cold trap and thm 4ecay vesool are diaoonnected; and then tho iodine-125 loaded substrate p~trticlas ert reatoved. f=ore the decay veasei.
In contrast to cur7rent technology, the invention has the following advantages. It avoids the ~xaking and handling of radioiodine solutions at the roactor site, the dispensing and evaporation o! redioivdine solutions nt the radioactive source manulacturidg Dtte) and tho aeaoaiat~ad ra4iologicel hadatrds and costs at both aites.~ The invention also pravidea source substrates ~ohich are very uniform is their radioactivity content relative to sub~tratea prepared by other ~nethoda.
A broad object of the invontion is to provide.subetrxtes bearing iodine-1~5 for use in sealed radioactive sources by a method that le radiologicaily safer and less costly than current methods.
Another broad object of the invention ie to proviso a m~thoa of making iodine-1Z5 b~aring sobstratas for use in sealed radioactive sources ehnt are more consistent ~oi,thin a batch in _4 _ their radioactivity content than those made by vther.aec.hode.
another broad object of the invention is to provi9e subetrotva bearing iodi»4~i25 for ua~e in raQiodctive eouroae by meano of a 4ry process in a seraled ay~tem uhieh Qoe6 not involve rediaawtiva iodine so7.utiong.
A ep~oiric object o1 the invention is to provldo a t~st?~od of inking $eoliea substrates bearing iodine-iz5 Poor use in sealed brarhytherapy sources and other types oP sealed radioactive 6all~,'C~~ .
IQ BRIEF DESCArP'i'IGM OF THE DRJI~PIHO
The Figure ~ia a schematic draorirrg o! a xeno» gas hattaling Byetem connected to a~ xenon irradiation ahanfber in the core o! a nvcloar reactor and tv m decay ve8pel cor~ta~ining substrate pnrtiolar.
DESCRIPTION OF THE PREF$RRED E~ODIM~?iT8 zn principle, the ob7eate~ of the invention are~~aehlavpd through assns of absorbing and holding xanvn gas at low t~mperaturo within partiel~a of a Suitable substrate n~ateriii.
Ths xe»on gas must contain a suitable concentration of ~o tsdioadtiye xenon--1~~ ~rhich decays tv a Buitnble amount of iodine-1z5. The decay of the xenon~iZ5 xuet~,tdke place at temperatures above the xenon boiling point eo that the xenon~x~5 remains in the gag phase a»d consequently the generated lodi»e-1~5 is urii~ormly distributed throughout the absorbing aubetra.te masm. Tha substrate material at room temperature must later tis~ly retain the iodine-lzs produced from the decay o~ the xenon~125 but not iretairi the xenon gaa.
-s-Zaolitee~art the prolezred substrate meterietl. Zeolftes are a olaae of crystalline molecular s3evea that occur naturally or oan be eynthesisad irt powder lorn~. 2~hny are otable inorganic cvmpounde~ that have open a lumano ~ s i 1 ice to Fra~tewarke that a l.l.oWg thaw to hoot ether che~nieal epeele~'within their gtrueturae.
Zaalita~~e arc uped in large quancitiee in sang industrial appl3eationa. comprehenelve inlorraation oat $eolit~e is given in the textbook 'Zeolite Molecular SSeveB' by bonald p. Hreclc, John Wiley dad Sons Irc., New York (i974), vhiah is incorporated herein by rei~rence.
Zlolitas have sxaollent properties for use as substrate materials in radi0llctive aourcee. The relsvaht prvpsxtias of zeolitee in this regard include good heat ana radiation resistance, eativn sxehange capaoities comparable with organic xoaine, good capacity tvr th~ edaorptivn and retsntien of radiosctive iodine, low density and average atvmie number of elemental certstituenta weansr~q loo attenuation or lvv-energy photons, and with a binder ran be formed into durable pellots~ or spherical beads iri appropriate sizes.
ao In a preferred embodit~eat, the substrate partiolQS~ are driod gevlit~ molecular sieve particles, prelerabZ~ spheres, that beve been silver-doped by catl0~i ~xchdnga are employed ea the gub9~trato material. 1~ e~aalJ~ metal vo~esl lilted with the zeolite spheres is atts~Ched tv a eetiled gas handling syst~ and ovacuata~d through a valve on th~ ve~sel.. The vessel and zeolite spheres aro then Cooled to abc~Vt -75aC by imaersion v! the vessel in mol~.d carbon dioxlda powder (dry iced. The e.ctual dry foe sublimation tearperature at standard (atmospheric) pressure ie -78.5°c. The cold taolite sphere mass is pertused pith a volume of xenon ges3 highly enriohed in the stable isotope xenon~124.
The xenon gar ha~ bean just prsvicuely irradiated with neutrons in b nuclear reactor and contains a suitable anvunt of radioactive xenon-lZ5 farmed 9uring the irradl.atioh via th0 , nuclear reaotivh xenon-lZd (n.gs~mr5) xenon~la5. Most of the xersah-la5 (half-li!~ l7 hours) is allov4d to decay to ~.odirte-12S (hsilt-lifo 60 days) whilst in contact with the xeolits spheres. The iodine~1~5 so permed is entrapped within the eovllte Btrvaturg or becomms chetsically bauOd with the silver dapant in the spherms.
Ins either casA thA iodine-l25 remains rirmiy e~ttaabe~d to the eeolite spheres vhsn) after a suits~ble deoay period, the vessel) and ~eolite ~phsreg are returned to room temperature and the xenon gas ~.e pumped away to ba re-irradiated in the reacto;. The cycle may be repeated a number of tiasss4 until the~ arvunt of iodine-Z~S ors t~ho saolite spheres reaches the desired levAl o!
rad~,oaativitY. The olos~ed vassal vorstaining the s;eolite spheres may then be subjected to a heat treatment to t~rther s~tabiliae o the adherence Cr the iodine-1~5 to the s3pherwr. Thnn~the evacuated vessel, with its valve closed and containing the reol~te l~phsres, is re~eoved free the gas handling sygt~a. The apherae are removed from the v~sasel and may be ured withcvt i'urther treatstent as radioactive substrates it radioactive sources. .
Opti4nally at this stage, the zeolite apher4m xith bdeorbed iodinG~laS may be heated to the tanperature et which the sreolite etruotura collapses and vitrification oacurg. Tha vitri.=ication tampargture for pellitizeC zeoZitve is typically ih tho range vi trOtO about Aoo°C to aba~ut l~OV°C, vitrl,tication results in hat'd glassy spheres Chat are smaller than ths~ originals $r~d that have arihanced propsstigs Eor certain appliCat~-, ~n particular, mechanical axrahgth is i~aproved and tha potantiex tvr abrasion of radioactlvs material from the ~aur=nc~ With attendant radiological haaard is r~duced. The potential fen tha leaching of redioactiva material from the sphorea is also reduced. Thi~ ie important in io applications involving contact With liquids, and is of particulaz importance in connection With implanted braehythera,py s~ouraee olhere a bleak in the eneapeulativn ef A source arould oxpvev ~e spheres to body lluids.
Xenon gas ran be strongly absoxbed by certain types of soolitss at low te~iperature~. Romssrkably, 1 gram at either 4A nr 13X seolite at about -~ovc, rrhicri ie well above the xenon boiling point, will bbevrlo ovor 5o milliistars of xenon gas, 2'Aia is a vo~equerce of the special properties of seolit~ae; t?~e xenon gas btoms are clvse~packad into the zeolite cryetel lattice almost in ao s l.lc~uid phaaA. Zeolitee, when doprd with metallic eiesasnts such as sllvor, are v~rY erfective in aeqvestsring nearly vhaniaal i~
species of iodine from offlnsnt gas atreasv. Inrosmativn to this ettedt is given in the thosts "Zaolites as scavengers for Radioiodine 8peciea from the gas Phaee" by c.h. sa~apson and the references therein. This thesis is incorparatad herein by relerence.
filth ='~tere=tce tv the l~S.gure, ~ar~e is shov~n an operit~ng _8 _ nuclear reactor core il vhcrein is located a xenon gas target ohs~nber 1a connected via valves and tubing to an evacuateG xenon gee hanQlir~q system l0. All of the valves on the eyet4m gxA
closed. The target chamber cont~eine high-pu..tity xenon ga~o erf.riched in the sta~ole isotope xenon-~.2~. Tn~r target qaa is ixra4lated yith neutxons so that some vt the xenon-1z4 nuclei capture a neutron anc~ becotoe radioactive xenvn~t2s nuclei . l~tte~-a euitaDle i,xrediation period that e~xlowe p~yfficient build-up of xenon-»5 radioe~ctivity, a~ually about 1 day, valves ~ vi end V~
1,0 ere opeud~ and the xenon target gas end generated xenon-lZ5 are cryo-pumped to a sold trap i3. This is acavmplieh4d by cooling the cold trap ~rith liqu3.d nitrogon and theroby reduc~.ng the vapor pre~sure of xenon Co essentially eero by freeaing it to the solid state. During'the cryo-pwnping opCtation, the IImal1 dacxy vessel 14, previously f~lll~d vith suitable absorbing ~ubetrate ~rartidles 15, and puaped out using the vacuum pump ls, i$ immersed in a guite~ble oold medium so as to reduce the temperature of the suDatrate particles to betW~~n about -70°C and about -80°c to thereby attain good xenon gas absorption vilicienay. valve vz is :a thQn cloned and valve V3 eepaxating tho cold trap troe the decay ve,sael and valve V4 on the devay vsesel era opened. The cold trap 13 is v~atmed to room temperature allowing the frosen solid xenon to return to the gab phase ahd to expand into the deCBy vessel l4 ana~re it is Wrifvrmiy absorbed by the oold substrate particles. Ve,lve Vd is theil closed. The cold medium ~,g bristly removed tro~n around tl~e dece~y v~ssel 1~4 in ordef to faci7.itate an accurate meeauresent o! the amount of xenon-~z5 radioactivitx in .,g_ eonte~ct With Lhe substrata particleB by se8ns or 4 rbdiativn detaotor 1'~ .
With valves V3, V4 and V7 closod, valves V5, V6.and V8 are opened to a~.lov n fresh cb~xrge of xenon target gas to ilv~r from the storage ve~oeel is into th4 qae target chnmbe: La for irradiation. Ve~lve V1 iB then closed and valves v2 and V3 ate opened. ~,'ho lines are Gryo-pumped free vt xerian by temporarily imtaereing 4 cold rings= 19 of the storage vvseal 18 itt liquid ~1i'ttogen. A11 peen valves are then CIOged. After a eui~table 1o daoay period, usually 1 to 3 de~yo, during which rise the decay vessel 14 ie cvntiruouslY kept Geld at a temperelture batweer~
about -~o°e and about -eo°c in vrc~er to minimize the internal gag pressure) the sold finger ~9 0! the atoxage vessel 18 is again te~tporari7,y avcled with liquid nitrogen to a temperature between about -190dC and about --t00°C. V~tlvos V4 and V5 are opelloc3, and the sold medium ie removed l=am around the decay ve8sel. ThH
xenon t?fan fldwu from the decay vesoel ~4 to the atorege vegsai 1A loavlng the iod,ine~laS behind oe the substrate p~rt:lClms.
Then all open vAlvas Ore clocsd. The cycle taay be repeated to gild up the enovrtt of iodine-125 vn the substrate particles.
then the substrate particles 15 mre eutEicle~ltly loaded With iodine--185 and any xenon has been pumped array, xhe eiosed inn evacuated decay vassal z4 and substrate particles l5 may be hAatod to a tempart~ture betveen about loo°c and about aOOnC to chetaically gtabiliae the iodino~125, nrd then cooled to a tempexa,ture batt~ean about 10°c and about 30°c and pumped upon for a short period to re~o~e a~~y iodlina-1a5 l~tt ire the vapor pheso.
~10-The decay-veeael 14 ig valued closed, disconnected at ~o frara the gee handling eysteea 10 and ret~cved tv s ventilated le~aiiity fox =urther handling. The nearly radloaictiva ~ubstra~te particles 15 are thon romovad lros the decay vasbei ld and eaa~pled for quality assurance taste prior to being available for further proaessi.ng such as vitrification or ivr vsa in radioactive evurooa.
It vih be reeocpnized that the system depicted 1n the Figgie is a ai.rplo one. In practice, multiple decay veaoel8 to hold io substrate particles) and even multiplo reactor gas~target chdmbero xay ba installed to add flexibility and capacity tv the sxstem.
Ih a preferred embcdi,mcnt of the a~athod described adova) the substrate particles are zaolite spherer sop~a oritn silver by nation exchange and meant primarily !or use in brachythorapy oourcae) the xenon target gag is enxiched to over 50 p~r cent in the xenon~124 stable ievtopo, and the cold medium is aolid carbon dioxide (dry i~co).
PRGPI~ir't'IC EXAMPLE
o A 5o milliliter volume or x~non gas onriahed to over 99 per cant in xenon-1~4 ie irradiatmB in a nuciea~r~,roactor for Z4 hours at a tDermal neutron flux of 5 x 10i3 nautrone pot square dar~tiatetar pex second. fhe amount of xenon-12s (half-life 17 hoys'a) produced et the end of the ~.rradiation i.s approximately coo ourieo .
At the end of the irradiation, the xenon gas i.s tranglerred to a small decay veaael containing io,oov silver doped type ~3X
~11-~eolita mpherical beode cooled tv approximately -~3°c with dry ice. The decay ves8al is then valves closed, and kept cool With dry ice except fox a period of about 1 minute at the beginning xhen the dry ice ie~ xeaiovesd ao Chat an acottxate radia~tiori reading of the deoay vea~sel c4n be taken. The total internal volume et the 9Qcay vessel ie 1 to 2 billilitors. The dl,ameter of aach zevl3te bead is o.65 m,illf.motars and the i.o,0o0 beads essentially fill the decay vessel. Nearly all o! the rerun is abmorbed end the gee p=eoeute inside the decay va9ael is les8 than 1 atao~phare.
lifter a ?~ hour decay periell, the xonvn is punpea away to a 8torsg~ vessel.. 11t this stagy there ie a total. of appraximat~ely Z.s curies oP iodibe-ia5 on the zeolite bead substrates, or aDOut 0.15 millicuriea per bead, xt is intendod to produce brachythorapy sources containing two beads each end having redioactsv~,ty cvnt~ts of 7..0 miilicuries each. Tt~e irxadiatiors/deeay cycle is therefore repeated ~ sore times over the next nine day8, whereupon, allawfng for ~aome decay during trie proce~ea) each bead has slightly in exces8 0! 0.5 fii111aur~,es of 2o iodine~la5 which ie oufficietlt to make too-ba~,d ~ouroQe co~ta~iniag z miliicu~cie per source. (Note t~rat the 24 hour xenon irradiation period associated with a partioular eycxe vvmme»eeg 48 Z'IOIlTg into the 71 hour decay period of the previova cycle).
The beadg are transferred from the decay vesse~. into a quartt vial that is then flame healed. The rtv;artz vial is placed in a lurnace at zoom temperature. The furnace is turned on and ov~r a period of one hauz~ the Ylal ana beads ere heated to ~lZ-l000°C. In this psocosa, there ~.s no loss of iodine-iZS) but the beads are vitrified and ~ceduoed in diameter by about z5 I,~er cent.
The bea4e aQhexs to each other very slightly. but upon cooling they are easily separable by shaking and are ready for uas fn radioaCtivs sources. -other pvrou8 materi$,lo, such as charaoai particles) possess otrong xenon absorption and iodine retention properties and may be substituted ror the prslezrad ieel3ts aubet~rats particles.
certain non-porous end noh-absorbing substrata Aateri.als with surfaces having affinity ~o~ iodin~, such as ai7.ver wires) may be substituted for the pseterrod $avlita substtato particles.
although in this case, because there ie no xenon gee pressure reduction by absorption, decay vessels capable of sustaining internal gas preosures of s~verai tone a! atmospheres would be required. Also xenon-iss may ba produced by ~oaang of a charged particle accelerator, ratter than a reactor, by irradl.ating a.
xenon gas target oontairiing et0ble xenon-~ia~ with protdne. All of the~a modifieationa are co~tnmplated and enaaapasoed by the invention. 111eo, the vitrification process ~aay be used for ~4 aeolites bearing other radioisotopes such as palladium-lo3 and ytterbium-l69.
Although the invention has been described in conjunction with epaeitic embvaiments, it is evid~ant that many alternative$
and variations dill be apparent to those sxillaa in the art in light at the foregoing deeeri.ptier. Accordingly, the invet~tlor ie i,ntsnded to embracs a11 of the alternatives arid variations that fall within the spirit end scope of the eppnnded claims.
The above references are hereby incorporated by refer~nae.
Vl~
Claims (14)
1. A dry-proceed method for producing iodine-125 loaded substrate particles for use in radioactive sources comprising the steps of:
providing a plurality of substrate particles; and contacting the substrate particles with xenon-125 in gaseous form during the radioactive decay of the xenon-125;
wherein the substrate particles retain iodine-125 generated by the radioactive decay of the xenon-125.
providing a plurality of substrate particles; and contacting the substrate particles with xenon-125 in gaseous form during the radioactive decay of the xenon-125;
wherein the substrate particles retain iodine-125 generated by the radioactive decay of the xenon-125.
2. The method of claim 1 wherein the xenon-125 is produced in a nuclear reactor by means of irradiating with neutrons a xenon gas target comprising it excess of fifty per cent of a xenon-124 stable isotope.
3. A dry-process method for producing iodine-125 loaded zeolite particles for use in healed brachytherapy sources comprising the steps of:
providing a plurality of zeolite particles;
cooling the zeolite particles to a low temperature; and contacting the cooled zeolite particles with xenon-125 in gaseous form during the radioactive decay of the xenon-125;
wherein the cooled zeolite particles retain iodine-125 generated by the radioactive decay of the xenon-125.
providing a plurality of zeolite particles;
cooling the zeolite particles to a low temperature; and contacting the cooled zeolite particles with xenon-125 in gaseous form during the radioactive decay of the xenon-125;
wherein the cooled zeolite particles retain iodine-125 generated by the radioactive decay of the xenon-125.
4. The method of Claim 3 wherein the zeolite particles are doped with silver.
5. The method of claim 3 wherein the zeolite particles are spheres with diameters in the range of 0.2 to 2.0 millimeters.
6. The method of claim 3 wherein said low temperature is about -75°C which is approximately the sublimation temperature at atmospheric pressure of solid carbon dioxide (dry ice).
7. The method of claim 3 wherein the xenon-125 is produced in a nuclear reactor by means of irradiating with neutrons a xenon gas target comprising in excess of fifty per cent of the xenon-124 stable isotope.
8. A method for making a plurality of iodine-125 loaded substrates comprising the steps of:
(a) providing a source of xenon-125 in a cold trap;
(b) adding the plurality of substrates to a decay vessel, (c) cooling the decay vessel to reduce the temperature of the substrate particles for improving xenon gas absorption efficiency of the substrates;
(d) interconnecting the cold trap and the decay vessel;
(e) warming the cold trap to cause the xenon-125 to expend in a gaseous state into the decay vessel;
(f) for a predetermined period of time, permitting radioactive decay of the xenon-125 to iodine-125 while in the gaseous state and in contact with the substrate particles, the iodine-125 being retained by the substrate particles;
(g) disconnecting the cold trap and the decay vessel; and (h) removing the iodine-125 loaded substrate particles from the decay vessel.
(a) providing a source of xenon-125 in a cold trap;
(b) adding the plurality of substrates to a decay vessel, (c) cooling the decay vessel to reduce the temperature of the substrate particles for improving xenon gas absorption efficiency of the substrates;
(d) interconnecting the cold trap and the decay vessel;
(e) warming the cold trap to cause the xenon-125 to expend in a gaseous state into the decay vessel;
(f) for a predetermined period of time, permitting radioactive decay of the xenon-125 to iodine-125 while in the gaseous state and in contact with the substrate particles, the iodine-125 being retained by the substrate particles;
(g) disconnecting the cold trap and the decay vessel; and (h) removing the iodine-125 loaded substrate particles from the decay vessel.
9. The method of claim 6 wherein step (a) includes irradiating xenon gas enriched in stable isotope xenon-124 with neutrons to form the source of xenon-125.
10. The method of claim 8 wherein step (a) includes irradiating a xenon gas target containing stable xenon-126 with protons to form tho source of xenon-125.
11. The method of claim 8 wherein the substrate particles cash comprise zeolite.
12. The method of claim 8 wherein the substrate particles each comprise charcoal.
13. The method of claim 8 wherein the substrate particles each comprise silver.
14. The method of claim 8 further comprising the step (I) of heating the zeolite spheres with adsorbed iodine-125 to the temperature at which the zeolite structure collapses and vitrification occurs.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7454998P | 1998-02-12 | 1998-02-12 | |
| US60/074,549 | 1998-02-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2261444A1 true CA2261444A1 (en) | 1999-08-12 |
Family
ID=22120158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2261444 Abandoned CA2261444A1 (en) | 1998-02-12 | 1999-02-11 | Method for making iodine-125 loaded substrates for use in radioactive sources |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU2507299A (en) |
| CA (1) | CA2261444A1 (en) |
| WO (1) | WO1999041755A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113351017A (en) * | 2021-06-23 | 2021-09-07 | 中国核动力研究设计院 | Extraction device for gaseous iodine in loop for producing iodine-125 |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1946797A3 (en) * | 2001-12-12 | 2009-03-11 | The Univ. of Alberta, The Univ. of British Columbia, Carleton Univ., Simon Fraser Univ. and The Univ. of Victoria | Radioactive ion |
| CA2470006A1 (en) * | 2001-12-12 | 2003-07-03 | The University Of Alberta, The University Of British Columbia, Carleton University, Simon Fraser University And The University Of Victoria, Coll | Radioactive ion |
| BE1023882B1 (en) * | 2016-06-28 | 2017-09-04 | Inst Nat Des Radioéléments | METHOD FOR PRODUCING A XENON RADIOISOTOPE FRACTION, IN PARTICULAR XE-133, XENON RADIO-ISOTOPE FRACTION, PARTICULARLY XE-133 |
| CN110648779A (en) * | 2019-07-04 | 2020-01-03 | 中国原子能科学研究院 | Circulation loop for preparing I-125 by reactor irradiation |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4447353A (en) * | 1979-08-06 | 1984-05-08 | The United States Of America As Represented By The United States Department Of Energy | Method for treating a nuclear process off-gas stream |
| US4323055A (en) * | 1980-04-08 | 1982-04-06 | Minnesota Mining And Manufacturing Company | Radioactive iodine seed |
| US4729903A (en) * | 1986-06-10 | 1988-03-08 | Midi-Physics, Inc. | Process for depositing I-125 onto a substrate used to manufacture I-125 sources |
| US5633900A (en) * | 1993-10-04 | 1997-05-27 | Hassal; Scott B. | Method and apparatus for production of radioactive iodine |
-
1999
- 1999-02-11 CA CA 2261444 patent/CA2261444A1/en not_active Abandoned
- 1999-02-11 WO PCT/CA1999/000127 patent/WO1999041755A1/en active Application Filing
- 1999-02-11 AU AU25072/99A patent/AU2507299A/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113351017A (en) * | 2021-06-23 | 2021-09-07 | 中国核动力研究设计院 | Extraction device for gaseous iodine in loop for producing iodine-125 |
| CN113351017B (en) * | 2021-06-23 | 2022-04-08 | 中国核动力研究设计院 | Extraction device for gaseous iodine in loop for producing iodine-125 |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2507299A (en) | 1999-08-30 |
| WO1999041755A1 (en) | 1999-08-19 |
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