Report Detailing a Breathing Experiment with Nitrogen 13 (Incomplete Document, Pages One Through Three Are Missing) (Redacted)

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BEST COPY AVA \ w cylinder bounded by the two czmera faces. Thus back q round radiation was reduced to below 1event / sec, even without the use of 3.ead cell imation necessary when Esinq s in q le photon isotopes. The geometric eff ice n cy of detection w.7as reduced, however, t o below ZSS ~'of t.he positron events within the field of the camera. direction of gamma emission is preferred,events were not 2e tec ted unless the en is sion was nearly zlcn? the axis connecting the centers of the camera crystals.1 The smaller eet ect or vas i! pair of crystals 13 cm diameter, 5 cn thick z nd connecteil t o simple electronic modules allowing manual over intervals vzrjring from 30 sec to5min, on count rate. -

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on which the positron was ann hi late d.In experiments 1-7 this detector was placed A-P over the subjects ' left upper lung lobe,left experiments the camera vas placed inan A-P position centered over the left knee. In this re Fort, only total activity detected by the caner? I-' is reporte2. Image recovery of the spatially resolved 1 9 concentration is a n extremely con pli cate ? n roc ess for the data of this stcdy, for example see ( 4 ! , (9). Vith the low count rates obtained i n tkis study, reasonc7hle pi.c ture s dnd reasonable kinetics cannot both be obtained from the data.Thus only kinetics of the full detector field

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adjusted needle valve t o maintain the circuit between C.2-0.4% 02 of the starting value. Yo noticeable breathing resistance vas reported by any of the su hj ect s. Each subject took three rapid, seep brest hs at kot ht ? ? est z rt artd finish of re breath in ? t o e::p?e?ite ri zinc in the circuit zn ct5e 1.uncjs. The study vas Cesianed t o measure "1'3- kinetics durinq a 30 Tin up tz ke of up t o 100 inin TOOT;: air breath in ? (FiF.2).This tine inter v zl vas considere2 the maximin possible study tine since it covere? 1 0 half - lives of 13-Y, i.e.a reduction in count rate of 7 H or Tore he fore Set ect crs reache? essential Iv backFrocn6 levels of rc c ict ion.

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350-450 nrad to the lun(rs and about half the lung dose t o the tre che a. Doses estimated for other internal organs both b17 positron ann hil ation Data anz lysis F iq ureA also shovs the ext rene dop in ance of 13-1: radiologic decay on the ex peri a en tal data. The desired in spira tory profile was a square vsve of 30min duration(solid tr sce at top). Py Se cay ill one, 2closed volume of 13-Y would be recorsed as the dec reas in q trend of triangles.Tissue 13-I? con cent rat i cns vo ul d be expected to show c mn ke the detected s iq nal follow the time ccurse indicated Sy squares. em one nti al c7cccy function vvith 2 1n.Q v in half - life. FTcte that tke

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count, then multiply by e~p(+lO.O*Tm/.693)~vhere Tn isthe sp pro pri ate mean time of the ssmple period. radioactive source i s observed from TO t o Tf vhile decFyirq vl it bF One can show that if e corresponds to the original quantity of isotope decayed s t 'If the sampling interval (Tf-TOI i s less than T/%,Tm is nearly the mid-point of the interval ; for lon aer intervals Tm is shifted t o earlier times, thus2ec reas in a the mannituse of the decsy correction. Pecause of the importance of isotope fieca~r, in sever zl a8d it i one ld

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effect,the de czy once again appesred t o be corpletely l3-€7, with an PRIVACY ACT MATERIAL REMOVED .

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FiGure 4 shows the degree of 02 anc7 13-Y control achieved clurinq the 30 min re bree thin a period of exp. 8. As seen inthe upper trace, the closed circuit Faint a in ed an Fi02 of 20.8 to 21.0% during the entire period. Pez r fy2s qood values vcr e Fchieved i n sll other experiments (data not shovn). The next Fortion of Fig. 4plots in s mares the raw counts of rs di ation recorc'ed over a section of in spira tory hose. Sone lag is seen in the first (1 min)point, but e smooth exponential fall is apparent thereafter. Decay correction of the hose activity is also ploted inFig.4. Overall constancy i n this run vas4% rns. The slight upvard bulae is not vel1 understood, but probablv includes effects of slight lee kaye, uptake of isotope into body tissues, and slight reaction of q as vith the scrubber. The data of ex?. 5' is similar. These neasurenents vere not per for red in ex?. 3-7; but all fol loved the sage ?!as nix jn can6in s pir sti on 5.nz taf rm as j a cent tis e inter v z lz vere cunr?ecl i f necessary t o ?.!Y counts vere rec or led from the :-.nee betveen 10L?.O an6 106.9 rin.

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Eo. 1. The approximate 1 EE uncertainty is 7.0 cpm calculated as the scruare root of t h e raw count. A 1 9 minute background check performed less than 1 hour later vith this cletector geve 2. counts in19min,for a rate of 0.16 & 0.09 (1SE) cpm. The net 13-P? knee activity is then of the data and background neasurements. Decay correction back tothe of the experiment for Trn = 105.0 min and = min is 1470, so the reported corrected knee activity is 1.44 si: 0.21(2SE) cpm a t Performing the same type of background and decay correction for ell the data of exp.2q ives the curve shown i n Fig. 6 . The initial rise inactivity continues throuqhout the measurement period, evPn more than1 hour after cessation of 13-E? breathing ! The un cert z in ty Sue t o strong background correction in cress es cont.inuously until the Gzta i s unusable heyon6 about 115 pin.P evert ke less,the relentless rise in corrected 13-1: activity is much greater th sn experiment21 vas used. The larger detectors(an3lesser 1ea.d shieldincj) used i n

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differences in detector tuning, and subject size and exzct location in the detector field.Vith the possible exception of exp. 7,all subjects ' knees had a n unrnistakeoble rj sein 13-11 activity after The marked rise in knee 13-1: levels relatively long after the end of radioactive gas inspiration is, t o put it mildly,quite a surprise. Ye had anticipated the possibility of very slow kinetics that would appear as a nearly linear rise for 30 min followed by a decrease so slight as to appear r.eerly horizontal. From figs. zpncrent that exchanue is even slov ~ er,resisting the q radi ent for excretion €or atleast an hour. this result is due to a specific technics3 artifact,then to discuss sy ci fic late rise could he observec?. 8. Possible technical artifacts vcr e exapined in Se teil. Openin? the Fnsniratory valve vas verifies repeat e ? ly, and there breath in q rebreztking. Y'icers sn6 enercp disc r in in at or s were e::amined reneate3l.y; the enerqv fi is cri mi nation circuits shoved A small amount

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(Vhen this occurs, gamma rays are frequently arriving E it the detector before a previous event has been s.nz.lyze6 for the proper enerpy; one o r both events are then specific conditions of exp. 1-7 show that even countinq gamma rays arriv in q not in coincidence (about 3-Fto tires greater than the coincidence rate) troulcl not put the knee 2et ect or s in a pile-up experiment wheR all 13-€? gas sources were vented outside an8 knee The danger became - vanishing ly small later in the events fell Icrelov 10 counts per second but cont-inued the 6ecay-corrected rise. :.'e note that the large detector in ex pts 1-7 anzlvsis of that data is ccnylicstet.3 by pile-up. The possibility of cjamna ray flux from non - knee cw.coulr3 / also give i! spuriously high count. !?cvever, i n siculstec? ex per in ents

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The very large decay correction required makes the decny rate of the gas an in portent ges tion. Repeated experiments t o measure decay of cas obtained from the same source r ani! prepsred inthe same manner consistently gave clean half-lives such as fig.3.Ifr for example, a substantial fraction of the ori uinal aas was a slower 2ecsyinq inappropriately increasincf curve. (T’ith the same accelerator and gas handling equipment, both 15-0 a n 6 11-C have been produced.) The oxygen would not become a problem because it decays a t a half-time of 2 min. Furthermore, none of the gas prepared for these experiments had even P measurable trace of ozone or nitrogen oxides; gases which have been detected when a source gas co ntz in in q oxygen is irradiated. The 11-C could be a problem since it decays (T1/2 = 20 min).The Foss i hil itv of 11-C contamination leadinq t o these results can be exsnined as fol lov, ~ .ASP LIE ~ th z t the 11-C i s calc u let i cns show th z tan origin;.,l fr z c tion of 5 - 30% (1% i n CS.E? of su hi ect 7) or’ the oriqina3 positron e pitting isotope vo ul2have to5e Arquing z qa in st this contaninant level are the f z ct5that : the nc?s

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activation cylinder and transfer lines vcr e kept under vacuum when not analysis could support a s much a s IO-? in original.11 - C fractional and that no half--%' activity. Other isotopic contaminants are even less likely because they would have to arise from the experimental m te rials,and be The most extreme forrr! of a contamination hypothesis v e can imagine isa conteminant of 1 1 - C in its maximun'measurable concentration, about lo-?? of 13-!?, The 1 1 - C would be chemically tied toa molecule whose synthesis is not out of the question in the extremely active environment of high - radiation field bombardment, and the chemical Eorn of the Il-C would have to be subject to extreme biological amplification : say IJC?'. The initial entry rate of the I?CY into the subjects v7o ~ l dbe proportion zl to its ??3uncls.ncer and nearly all of i t reaching the alvleolus i.:ccl$ he Ficked up in blood and delivered to tissue. 3s. cvenide is essentially irreversibly bound t o oxidative enz!,7ma in tissue,its r zte of biological excretion \-oulC! Pnproach Q. Thus it could recruit al nost every molecule 6ctlivere6 by: correction 8ot.m t o constent con cent rz tion rec;ior.s. This is also fr mother tissues does not sh ovt ke c tron q rise in concentration

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Vith confidence that the experiment actually measured 13-N inthe knee,it becomes necessaary to consider mechanisms for the observed results.First, ET2 vould need a long residence time i n some knee structure, such that excretion of labelled gas vould be very slov over periods of 1-2 hours. Such M2 “ sinks ” could be physical, chemical, o r physiological in character. One physical possibility is ac as bubble phase, that would hold gas long,since 172 i s about 7 0 times more soluble in air as in tissues like blood (20). Pome theories hold that humans always have astore of gas micro nuclei, which are available for subsequent enlargement as the cause of decompression sickness(22). Cas areas can form inthe body and persist a while without any major symptoms. This has been demonstrated i n humans after altitude decompression (171, and clinically in routine Y-ray o r CF-T ex ani nation (7). Tndeed most of our subjects are divers with a history of decompression that might conceivably have resulted in some persistent for periods of weeks to nonths, and knee Y-rsiTs of su hj ect s P,P sc??orted so knee joint traction f.’ss not 2 s severe a s use6 to el jc it CZE _nocl::ets in red io los ic alex an in z t ions0.