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The radiosynthesis of [18F]DCFPyL on 2 distinct automated platforms with full regulatory compliant quality control specifications is described. The radiotracer synthesis was performed on a custom-made radiofluorination module and the Sofie Biosciences ELIXYS. The radiofluorination module synthesis was accomplished in an average of 66 minutes from end of bombardment with an average specific activity at end of synthesis (EOS) of 4.4 TBq/μmol (120 Ci/μmol) and an average radiochemical yield of 30.9% at EOS. The ELIXYS synthesis was completed in an average of 87 minutes with an average specific activity of 2.2 TBq/μmol (59.3 Ci/μmol) and an average radiochemical yield of 19% at EOS. Both synthesis modules produced large millicurie quantities of [18F]DCFPyL while conforming to all standard US Pharmacopeia Chapter acceptance testing criteria.

Irradiated natural tin target and 12-tungstocerate gel matrix were used for preparing a 113Sn and 124,125Sb sealed source. The distribution coefficients of 113Sn/113mIn and 124,125Sb ions on 12-tungstocerate gel matrix were determined in relation to HCl concentration. 12-Tungstocerate gel matrix was loaded with 113Sn/113mIn and 124,125Sb by equilibrating an irradiated Sn(IV) solution with 0.5 g of the matrix at pH 1 (HCl) for 24 h at 25 ± 1°C. A mixed sealed source of 113Sn/113mIn and 124,125Sb was prepared by packing 105 mg of the loaded matrix in the cylindrical cavity of a Chinese artelone capsule. The activity of the source was in the millicurie range. The source successfully passed quality control tests.

…the character of thorium radioactivity is unaltered by chemical treatment… It is well established that this property [radioactivity] is the function of the atom and not of the molecule. Uranium and thorium, to take the most definite cases, possess the property [radioactivity] in whatever molecular condition they occur... So far as the radioactivity of different compounds of different density and states of division can be compared together, the intensity of the radiation appears to depend only on the quantity of active element present. It is not at all dependent on the source from which the element is derived, or the process of purification to which it has been subjected, provided sufficient time is allowed for the equilibrium point to be reached…radioactivity is at once an atomic phenomenon and accompanied by…changes in which new types of matter are produced, these changes must be occurring within the atom, and the radioactive elements must be undergoing spontaneous transformation…Radioactivity may therefore be considered as a manifestation of subatomic…change.

Sealed 252 Cf sources in the microCurie to milliCurie range are routinely used in industry and research. At present, no reliable analytical method is available for precise determination of the activity. Very strong sources can be analyzed by neutron counting but the error is large. We propose to use γ-ray spectroscopy for such analysis. In particular, high-energy γ rays (above 1 MeV ) of fission fragments in equilibrium with the source are very convenient because they have little absorption in materials surrounding the source. It is found that the 1435.8-keV γ-ray of 138 Cs and the 1596.5-keV γ-ray of 140 La are well isolated and sufficiently above the background under these peaks. We have measured the γ/α ratio for the 252 Cf with an uncertainty of better than 5%. The experiment involved the preparation of several thin 252 Cf sources, alpha pulse height analysis, determination of α decay rate, and the measurement of γ singles spectrum with a well-shielded germanium spectrometer. The measured ratio and the γ-ray spectroscopy of unknown samples can provide the activity of 252 Cf in these samples.

A procedure is described for the large scale production of radiochemically and radionuclidically pure153Sm economically, from neutron irradiated natural Sm targets. Cation-exchange chromatography using 200–400 mesh Dowex-50×8 resin in the elution mode was used with 0.2M α-hydroxyisobutyric acid (α-HIBA) as the eluent at pH 4.7±1 and at 26±1 °C for this purpose. Typical decontaminations of carrier-free(155+156)Eu radioactive impurities, of the order of 5×102, could be achieved in individual fractions, from millicurie amounts of153Sm activity produced in milligram quantities of heavily neutron-irradiated natural Sm targets. Even though the153Sm yields were at about 3% at these decontamination levels of impurities, the yields increased to an average of about 50% at about 95% level of decontamination of these impurities. It has been shown that the method is successful for producing radiochemically and radionuclidically pure153Sm in sufficiently high radioactive concentrations for its probable conversion into153SmEDTMP complex, a potential radiopharmaceutical useful in the palliative therapy of metastatic bone cancer.

55Co is a positron emitting isotope that is of interest to the nuclear medicine imaging community. 55Co was produced by the 58Ni(p,α)55Co reaction and purified by chromatography. Our method has produced 55Co in millicurie quantities with a final recovery of 78% and an effective specific activity of 28μCi/μmol. The only radioactive impurity recovered with 55Co is 57Co(271.8d) and is at a concentration of ∼0.182% that of 55Co.

This paper describes a method for producing millicurie quantities of 4.48-h 85m Kr by neutron irradiation of natural krypton in the core of a nuclear reactor. The target gas was contained in a half-liter aluminum vessel residing in the reactor core. Irradiation at 1 megawatt for 1 h at a pressure of 40 psig (206 cm Hg) yielded a total 70 mCi of 85m Kr in a volume of 1660 cm 3 .

The178m2Hf nucleus, with its long half-life (31 y) and high-spin isomeric state (16+) is desired for new and exotic nuclear physics studies. The Los Alamos Radioisotope Program irradiated a kilogram of natural tantalum at the Los Alamos Meson Physics Facility in early 1981. After fifteen years of decay, this target was ideal for the recovery of178m2Hf. There was more than a millicurie of178m2Hf produced during this irradiation and there has been a sufficient period of time for most of the other hafnium radioisotopes to decayed away. Traditionally, separation techniques for recovering hafnium isotopes from tantalum targets employ solvent extractions with reagents that are considered hazardous. These techniques are no longer condoned because they generate a mixed-waste (radioactive and hazardous components) that can not be treated for disposal. In this paper we describe a new and unique procedure for the recovery of hafnium radioisotopes from a highly radioactive, proton irradiated, tantalum target using reagents that do not contribute a hazardous waste component.

Integration of betavolatics with radioisotope-powered piezoelectric micropower generators (RPG) operating in new resonant modes, attains nuclear-electrical conversion efficiencies of up to 30%, generating 1 to 10muW peak power with 1 to 10 milliCurie of Nickel-63. A 20mV-voltage-drop ac-to-dc rectifier employing radioactively biased MOSFETs is developed for efficient conversion of RPG-generated low-amplitude power signals

This paper presents theoretical and experimental studies on betavoltaic microbatteries using low-level radiation from 1/spl sim/100 milliCurie /sup 63/Ni thin films. The model indicates that powers of hundred nanowatts are possible with 50-100 milliCurie radioisotope sources. Two types of betavoltaic microbatteries are developed and tested. One is the planar silicon pn-diode with electroplating of /sup 63/Ni thin film, and the other is the bulk micromachined pn-junction structure with the inverted pyramid array. The obtained power is on the scale of one-nanowatt with an open circuit voltage of 128 millivolts, and a short circuit current of 2.86 nA. The output power can be increased using greater activity and efficient collector designs.

Terbium-152 (Tb-152) is of potential value as a radiotracer for radiolanthanides in positron emission tomography. We report the production of Tb-152 by heavy ion reactions at the ANU Tandem accelerator, and by the spallation method at the CERN proton accelerator using the on-line ISOLDE separator, obtaining microcurie and millicurie yields, respectively. After purification, a phantom image in PET is obtained which shows the feasibility of using Tb-152 for monitoring the kinetics of Tb-149 and other radiolanthanides. However, the current availability of this radioisotope will be restricted to major nuclear physics research centres.

UDP-GlcN[1-14C]Ac was synthesized in a single enzymatic reaction from [1-14C]acetate and commercially available precursors on both a microcurie (micromole) and a millicurie (millimole) scale. The reaction was catalyzed by the action of acetyl coenzyme A synthetase, inorganic pyrophosphatase, and the bifunctional Escherichia coli GlmU protein. Within 2 h 86 to 94% reaction is attained, and it approaches 99% completion overnight. GlmU protein was prepared in the form of a fusion suitable for nickel chelate affinity chromatography. Several methods were developed for rapid purification of UDP-GlcN[1-14C]Ac: an HPLC method handled micromole (microcurie) loads. Alternatively, ion exchange chromatography over DOWEX AG1 X-2 using a batch elution procedure was compatible with millimole (millicurie) amounts of radiolabel and yielded both chemically and radiochemically homogeneous UDP-GlcN[1-14C]Ac. These methods allow laboratories to quickly produce and purify microcurie to millicurie quantities of N-acetyl-labeled UDP-GlcNAc by a choice of methods from relatively inexpensive precursors.

The development of tritium nuclear magnetic resonance spectroscopy now makes it possible to determine the tritium distribution in virtually any organic compound at the millicurie level of radioactivity. Results of catalytic experiments show that in some cases a remarkable degree of specificity can be achieved when using procedures that are expected to produce generally labelled compounds. Conversely there are instances where specific labelling procedures are less than 100% successful.

The first use of the172Hf−172Lu generator system in industry is reported. Millicurie quantities of172Lu have been utilized for radiotracer studies of oil pipeline flow rates, refinery column residence times, and the performance of a coal liquefaction pilot plant.

A simple procedure is described for the preparation of millicurie quantities of the cancer chemotherapeutic agent, BCNU, labeled in the nitroso group with 13N.

SUMMARY In order to provide further information on radiation doses to the brain and meninges following intrathecal injection of 169Yb DTPA, 85 cisterno scans were reviewed here. It was found that a slow rate of clearance of 169Yb DTPA existed and that maximum doses of 10–70 rad to the brain tissues per millicurie administered could be expected in patients who showed a long-term retention of the radionuclide.

The x-ray system used was a Columbia Scientific Industries Corporation Portable X-Ray Fluorescence Analyzer Minilab 700 with a ten millicurie curium 244 source. This source was chosen instead of the available 30mCi Pu-238 or the 30mCi Cm-244 source because it could be supplied under a general radioactivity materials license. The XRF analyzer could be powered by a variety of power supplies, either AC or DC. All data were evaluated and best curves were selected utilizing the Honeywell Time Sharing System. Programs from the statistical library were used with minor modifications.

The primary purpose of a medical cyclotron is to improve the diagnostic value of Nuclear Medicine through the production of clinical quantities of desirable radionuclides. A medical cyclotron in the 15 MeV to 20 MeV energy range can produce 10 to 100 millicurie quantities of intermediate and short-lived radionuclides. A medical cyclotron in the 25 MeV to 30 MeV energy range can produce curie to multicurie quantities of intermediate and short-lived radionuclides. The considerations for selecting a medical cyclotron used for radionuclide production are radionuclidic purity and production capabilities. The influence of nuclear reactions, particle energy and isotopic enrichment of target material on these considerations is discussed.

A nomogram is presented to estimate the radiooctivity of99mTc in99Mo−99mTc generators, based on equations of radioactive equilibrium. Since the parent element decays through two isomeric states of the daughter, the ratio of the total mass of technetium per millicurie of99mTc is a function of the time elapsed between two consecutive elutions. Values of the amount of99mTc expressed as a mole fraction or in moles or grams of total technetium per millicurie of99mTcm are also presented.

Three commercial Na125I solutions (Amersham, New England Nuclear, and Union Carbide) have been examined with respect to multiple parameters affecting their use in the radioiodination of three representative peptides (insulin, growth hormone, and gastrin): % of radioiodine incorporation in protein; immunoreactivity and non-specific binding properties of the radiolabeled proteins; pH, volatility, and radionuclidic purity of radioiodine solutions; and vial construction with respect to multidose use. All three commercial Na125I produced radioiodinated proteins of good quality for use in radioligand assays. The radioiodines differed with respect to the amount of iodine released during initial vial opening as a consequence of different pH levels: 15 nCi/mCi (pH 12.5) to 1.0 microCi/mCi (pH 7.5). Two of the three products were shipped in vials with poor construction with respect to multidose use. Selection of a radioiodine was therefore reduced to the secondary considerations of iodine volatility and vial construction. The volatilized radioiodine observed during the spill of millicuries quantities of unbuffered pH 7.5 Na125I was 14 microcuries per millicurie within the first 30 minutes. One thickness of rubber gloves reduced potential skin contamination from an accidental spill to insignificant levels: 20-30 picocuries per microcurie. Common good housekeeping procedures: i.e. rubber gloves, laboratory coat and a fume hood were found to be sufficient protection to eliminate most radioiodine volatility and contamination hazards associated with protein radiolabeling procedures.

A tube is described for the utilization of the D — D reaction in the production of neutrons. A capillary arc ion source and a target of heavy ice are employed. The activation in Ag by the neutrons produced with 280 microamperes of unresolved ions at 200 kv was ten times that obtained when a 200 millicurie radon beryllium source was substituted.

Internal bombarding technique to produce high specific activity on small samples being used for 25-MeV betatron at Tohoku University is described. The samples are placed inside the doughnut at the end of a blind cylinder inserted from outside; thus samples are bombarded under one atmosphere, just behind the bremsstrahlung target where the X-ray density is extremely high. Design and the operational characteristics as well as some examples of its application are presented. More than 1 millicurie of Cu62 was produced and the specific activity becomes 500 times compared with external bombardment.

A sensitive real-time airborne dust mass monitor has been developed. Its operation is based on the measurement of beta-radiation absorption by aerosol particles collected onto a small area by means of inertial impaction. The device collects particles of unity density larger than 0.3 µm in diameter with nearly 100% efficiency at a flowrate of 20 liters/minute. A typical atmospheric mass concentration of 100 µg/m3 can be evaluated in less than one minute, using a one millicurie C14 source.

Radioactive sucrose, in millicurie amounts, was prepared by feeding a detached sugar beet leaf C14O2in air for 15 to 20 minutes followed by 5 to 20 minutes additional photosynthesis in air. The low endogenous sucrose in the leaf coupled with the improved tracer yield effected by the displacement technique gave sucrose with high specific activity. This sucrose-C14, hydrolyzed by 1% invertase, was a good source for radioactive glucose and fructose. Paper chromatographic procedures were used for the isolation and purification of the sugars.

The feasibility of using technetium-99m as a pertechnetate or strontium-87m to visualize and localize the placenta with the gamma-ray scintillation camera was demonstrated in a previous communication (2). It was shown that a frontal and lateral view of the placenta can be accomplished within eight minutes of an intravenous injection of one millicurie of radioactivity and be accurately localized relative to a radionuclide marker over the symphysis pubis. Large areas of reduced or absent perfusion of the placenta may be detected, particularly when implanted on the anterior wall of the uterus. An extension of this early study is presented in this report. The uterus was scanned in various stages of pregnancy, in the presence of fibroids, and in a single case of hydatidiform mole. Method and Material The results to be reported were selected from 150 scans of the uterus in the first, second, and third trimesters of gestation. All were performed either with technetium-99m pertechnetate (99mTcO4) or strontium-87m...

FROM a technical standpoint, radiation therapy may be divided into two general methods, namely, external and interstitial. The purpose of both methods is to produce within living tissue the identical biological effect. In certain instances either one may be indicated to the exclusion of the other, but, in general, they are complementary and offer two technical means to the same end. Ordinarily they can best be utilized when employed together. The present discussion deals exclusively with the problems of dosage in interstitial radiation and, therefore, the advantages of external radiation as an important adjunct have been purposely omitted. The determining factor in successful radiation therapy is the “tissue dose” or the quantity of radiant energy reaching all parts of a volume of neoplastic tissue. The term “tissue dose” is not to be confused with the millicurie, millicurie-hour, or milliampereminute doses. The latter deal only with the physical qualities of the radiating source. Due to the physical natu...

A method for extracting P32 from neutron-irradiated sulphur has been developed. The sulphur is melted under a mixture of acetic acid and acetic anhydride at boiling temperature, and the P32 is recovered from the residue left after distilling the acid. An apparatus for carrying out the process by remote control is described. It has been used for production of 100 millicurie amounts of carrier-free P32 at the Chalk River laboratories.

Due to the annihilation radiation of the positron emitting oxygen-15, H215O has great potential for tracer studies. The method of preparation utilized the fast exchange reaction between carbon dioxide and carbonic acid. It was found that the rate of exchange depended on the temperature, the solution used and the dynamic state of the solution. Utilizing this exchange reaction, water with a specific activity of 80 mCi/cc was prepared.

Placental imaging with 113mIn-transferrin correctly localized the placental site in 94 of 100 patients. There were 3 false-positives and 3 false-negatives; these errors are attributed to examination before the thirty-fifth week of gestation and to variable situs of the internal cervical os. The fetal radiation dose was 8 mrads per millicurie administered. The authors consider 113mIn to be the agent of choice for placental localization and imaging.

Equations are developed for nondestructively determining the thickness of a slab of material of arbitrary composition and density. The equations for determining the accuracy of the principle, the optimum distance between detector positions, and the required source intensities are also developed. For the particular case of measuring the thickness of reinforced concrete pavement a 1.32 millicurie source of 0.662 MeV gamma rays or a 0.782 millicurie source of 1.33 MeV gamma rays is required. This is to obtain a measurements standard deviation of 0.125 in when a 9-in thickness is measured with a 1-in radius by 2-in thick sodium iodide crystal and when 1-min counting times are employed.

Pregnant female albino rats were given graded doses of radiophosphorus after 14 or 17 days of gestation and sacrificed at intervals after injection through birth. One millicurie or less of P-32 did not increase prenatal mortality after administration on either of these two days. Two millicuries produced prenatal deaths when administered after 14 days of gestation but not after I7 days; some deaths attributable to the trauma of parturition were noted in both cases. A depression of the growth curve and of birth weight was produced by doses of 0.4 mc and larger after 14 days and by doses of 0.6 mc and above after 17 days of gestation. The curves of accumulated radiation dose to the whole fetus and to various organs and systems as interpolated to one millicurie are presented and discussed. (auth)

The reactor production of Rb84 by the Sr84(n,p)Rb84 reaction was measured, and millicurie amounts were found to be readily obtainable from isotopically enriched Sr84 targets. The fission-neutron cross-section for this reaction is reported here to be 0.0056 barn. The Rb84 was separated from the strontium targets by a previously unreported ion exchange method utilizing Bio-Rex-70 cation exchange resin. The Rb84 products were found to be free of detectable radiocontaminants.

Millicurie amounts of 55-hr 66Ni were produced by utilizing a flux of 2·45 × 1015 n/cm2/sec for the successive capture of neutrons by 64Ni. Yields of 39 mc, 55 mc, and 66 mc of 66Ni were obtained from 50 mg targets of 98·56 per cent isotopically enriched 64Ni for 48-, 72-, and 96-hr irradiations, respectively. The 66Ni was isolated as a purified product by precipitating the 110mAg contamination, electroplating the 66Ni away from 24Na, and by removing 58Co and 60Co by anion exchange chromatography. The cross-section for the 64Ni(n, γ)65Ni reaction has been remeasured in the ORR Reactor and the BSR Reactor by Lyon and Emery, and Lyon's original value of 1·5 b was confirmed. Based on the present work, the cross section for the 65Ni(n, γ)66Ni reaction is estimated to be 60–70 b.

The paper describes the principles involved in the application of coincidence counting to problems in nuclear physics, and gives details of the various methods of approach to the solution of nuclear level schemes, with some of the difficulties encountered. It is shown that the maximum source strength which can be used is inversely proportional to the coincidence resolving time and that the method of experiment has the great advantage over most other methods in that it can be used with very weak sources (sources having an activity of about 10−5 millicurie). An accurate knowledge of the absolute net efficiency of a Geiger counter for all types of radiation is required in the interpretation of the coincidence rates, and the method of achieving this at the same time as information is obtained about nuclear level schemes is explained. Further, it is pointed out that the method makes possible a simple and rapid determination of the total energy of disintegration of β‐radioactive nuclei and therefore of the mass differences between parent and daughter nuclei.

Joshi effect (±δi) an almost instantaneous and reversible photo-variation of the discharge current (i), is studied in various types of discharge vessels, charged with air, H2 and I2 vapour, and excited by fields due to continuous and alternating potentials (V). t was observed by a counter-sealer, and/or a galvanometer after rectification. +δi was observed under β-rays from a 50 millicurie Ra-Be source, and various frequency bands of the visible. The intensity (I) was varied over 30 times using the former, and 500 times with the latter. A 100% negative effect is observed near and above the threshold Vm; it decreases with increase of V. ± δi (disfavoured by a prolonged discharge) occurs within a restricted range of conditions, viz. low J and V. As these are increased, a sharp inversion equation follows which is fully reversible in respect of I and V. The minimum inversion intensity and the inversion potential vary in the order: violet < blue < green < yellow < red and, I2 H2 < air. ±δi is independe...

The use of radium and its emanation radon in the treatment of malignant growths depends upon the discovery that the cells of which these growths are composed are destroyed by exposure to gamma radiation. The sensitiveness of the cells of different growths is variable, but it is usual to take as the amount of radiation required that amount which is received by a cell at a distance of 0·5 centimetre from the source, during the destruction of 1 millicurie of emanation. This statement depends upon the clinical observation that 1 millicurie of emanation is able, in the course of its decay, to destroy all malignant cells of a sensitive type within a distance of 0·5 cm. As it has been definitely shown that the action is limited to each cell and is not transmitted from cell to cell, it is obvious that cells near the source will receive an excessive dose, whilst those at the periphery will receive one which is just adequate for the purpose. As the cells of the normal tissues are themselves vulnerable, though not t...

Studies were made to determine how to introduce radioactive phosphoric acid (P/sup 32/) into both larvae and adult mosquitoes in amounts that would be detectable with radioactive measuring devices. Aedes sticticus (Meig.) and A. vexans (Meig.) mosquitoes gave 544 to 897 cpm above background after they had been allowed to feed on the blood of rats that had received 0.375 millicurie of P/ sup 32/ in aqueous solution intraperitoneally 24 hours earlier. In three dissected specimens an average of 72 per cent of the radioactivity was found in the abdomen and 4 per cent in the legs. Second- and third-instar larvae of Culex tarsalis (Coq.) reared in water having an unknown concentration of P/sup 32/ had radioactivity ranging from 184 to 417 cpm. Fifteen per cent of this radioactivity was present in the legs and 45 per cent in the abdomen. Aedes sticticus females fed on water having an unknown concentration of P/sup 32/ gave readings of 577 to 1,192 cpm 1 to 13 days later. The legs had approximately 9 per cent and the abdomens 41 per cent of the total radioactivity. Aedes sticticus and A. vexans adults reared from the second-stage larvae in water containing 0.05 mu cmore » of P/sup 32/ per milliliter gave average readings of 41,147 cpm for females and 39,072 cpm for males. In later tests dosages of 0.01, 0.001, and 0.0001 mu c per milliliter gave 14,911, 1,612, and 522 cpm, respectively, for the females. It is suggested that a concentration of approximately 0.0001 mu c of radioactive phosphoric acid per milliliter may be a practical dosage for the treatment of larvae in flight studies of adults. Since adults may be readily tagged by feeding them sugar solutions containing small amounts of P/sup 32/, the use of this method may be desirable in many studies.« less

The preparation of 67Cu by the 67Zn(n, p) 67Cu reaction in a nuclear reactor was studied. Millicurie amounts were obtained from isotopically enriched 67Zn targets, and the fission-neutron cross section for the reaction was found to be 0·82 ± 0·04 mb. The 67Cu was separated from zinc and cobalt by a combination of anion exchange and chelate resin techniques.

Very simple radiation monitors can be constructed using only a cadmium sulphide cell, a battery and a microammeter. The construction of a versatile prototype unit is described, together with the development of monitors for detecting the transfer of radioactivity in radiochemical processes and portable ratemeters for localizing millicurie quantities in vivo. The limitations of the direct current use of CdS cells are discussed and some further applications within these limitations are listed.

Millicurie quantities of carrier-free 55 Fe and 59 Fe were obtained from irradiated cobalt and nickel targets. The fission-neutron cross sections were determined to be 3.30 ± 0.39 mb for the 58 Ni( n , α) 55 Fe reaction, 1.06 ± 0.12 mb for the 59 Co( n, p ) 59 Fe reaction, and 0.111 ± 0.013 mb for the 62 Ni( n , α) 59 Fe reaction based on a value of 61 mb for the 54 Fe( n, p ) 54 Mn reaction. The uncertainties quoted are the standard errors at the 95% confidence level.

The fluorod dosimeter system was used to measure the gamma exposure dose from mc levels of I131 to the neck, stomach, small intestine, kidney, bladder, and gonads of euthyroid and thyroidectomized dogs. The retention kinetics of these levels of I131 were found to differ from that of tracer observations; as a result of I131 thyroid ablation, large amounts of the radionuclide rapidly, left the body. The retention in extrathyroid regions, representing 76 per cent of the total effective retention, was not appreciably affected by the range in initial thyroid status represented. The measured gamma exposure doses were several times higher than predicted by the usual models. This was attributed to heterogeneity in I131 distribution within the extrathyroid regions.

1) It is now possible to predict the strontium-90 concentration in the world population for specified modes of atmospheric contamination with moderate reliability. For example, the average adult bone level in the eastern United States 5 years after the detonation of a specified quantity of fission products into the lower polar stratosphere can probably be estimated to better than ± 50 percent. 2) The concentration of strontium-90 in fetuses reached a maximum of 1.2 micromicrocuries of strontium-90 per gram of calcium in eastern North America and began to decrease significantly in 1960 and 1961. The ratio of the strontium-90 level in the fetus to the level in the average diet of the adult is about 0.08. 3) The average rate of turnover of strontium and calcium in the adult skeleton appears to be about 2.5 percent per year, although there is considerable difference among the various bones of the body. 4) The standard deviation for strontium-90 concentration in a population of urban adults appears to be about 40 percent of the mean. The distribution curve for an interval of from 60 to 0.1 percent of the population may be approximated by the log-normal function. In urban populations of Western culture the concentration for 5 percent of the population will exceed twice the mean, that for 0.1 percent will exceed four times the mean. 5) Cities in the Southern Hemisphere showed levels in bone about half those for cities of Western culture in the Northern Hemisphere in 1960, yet the fallout in the Southern Hemisphere is only one-fourth that in the Northern Hemisphere. This is attributed to differences in diet, with a higher milk component in the Northern Hemisphere. 6) A simple model for the strontium-90 concentration in the bones of young people as a function of their age appears to fit the experimental data. 7) The coefficients of the equation describing the relative contributions of the rate of fallout (direct absorption) and the cumulative deposit (soil up-take) to the strontium-90 concentration in milk have been calculated from the observed data for 1959 and 1960. They are as follows: rate factor A = 0.65 micromicrocurie of strontium-90 per gram of calcium in milk per millicurie of strontium-90 per square mile during the growing season; cumulative-deposit factor B = 0.12 micromicrocurie of strontium-90 per gram of calcium in milk per millicurie of strontium-90 per square mile at the midpoint of the growing season. The predicted levels in milk for 1958 obtained with these coefficients are in excellent agreement with the observed levels. In 1958 and 1959 about half the strontium-90 in milk was attributable to the rate factor, whereas in 1960 the contribution of the rate factor dropped to about 15 percent. 8) Future levels of strontium-90 in man are given (i) for the next decade as a result of the nuclear tests through 1961 and (ii) under the assumption that 1.0 megacurie of strontium-90 is added to the stratosphere of the Northern Hemisphere each year. 9) The radiation doses to the skeleton to be expected from world-wide fallout on the basis of a 3000-megaton (fission yield) war are also given.

Strontium-90, administered orally to dogs in a dose of 1 millicurie/kg caused disturbances in the carbohydrate metabolism of the liver, changes in the hepatic tissue, and a reduction in bile formation and bile excretion. Pathomorphological investigations demonstrated injury to the liver tissue, dilatation of the vessels (which was more marked in the center of the lobules), and early necrobiosis of individual hepatic cells. The total dose built up by the administration of Strontium-90 (in 180 days) was equal to 10–15 rads.

An internal probe technique of producing strong gamma‐n and gamma‐p activities with a betatron is described. Sources approaching 1 millicurie in strength of Cu62 have been realized. A typical specific activity of Cu62 produced in a piece of half‐mil copper 2 mm×24 mm is 7 mc/g.

Injections of 150–200 mc of colloidal radioactive gold into the intraperitoneal space and 75–100 mc intrapleurally have been found from clinical experience to be of considerable radiotherapeutic value. It is of importance to consider how far this experience in the millicurie injection required can be transferred to similar treatments with other isotopes, and in particular to the use of colloidal 90Y considered in Section I of this paper. A calculation of the probable doses given, in terms of rads, for some of the various conditions that may occur in practice may provide some contribution to the further development of this type of treatment. The integral dose delivered can readily be calculated from the half-lives of the isotope and the average β energy, but the actual dose delivered to individual tissues will depend as well on the volume of fluid in the cavity and the depth below the surface of the point considered. This variation will generally be different for different isotopes. Doses to the peritoneal...