Improvement ofin vivoneutron activation analysis of Mn using a 4p NaI(Tl) detector array

Summary Manganese contents in hand phantoms were analyzed by in vivo neutron activation analysis using a 4p NaI(Tl) detector array. Solution-type phantoms with varying amount of Mn and fixed amounts of physiological normal elements (Na, Cl, Ca) were prepared in a cylindrical shape to simulate fisted hands and were irradiated with the ⁷Li(p,n) neutron beam. The proton energy and polyethlyene cavity were set at optimized conditions established before. The g-ray spectra were accumulated under the anticoincidence mode. The calibration was done both for the 847 keV full-energy peak area and for the total area of ⁵⁶Mn, which is defined as the total number of counts anywhere in the g-ray spectrum from ⁵⁶Mn. From the analysis of the 847 keV peak, the Mn detection limit has been improved by a factor of 1.6 compared to the previous feasibility test thanks to a significant gain in the g-ray detection efficiency. Further improvement by a factor of 1.2 was identified when the total area of ⁵⁶Mn was used for the calibration. The final sensitivity and detection limit for a 20 mSv hand dose reached 12,050 counts/mg Mn, and 86 mg, respectively. The overall improvement achieved in this study will be a considerable contribution toward realization of the clinical application.     

The in vivo neutron activation analysis of calcium in the skeleton of normal subjects,with hypokinesia and bone diseases

A facility developed for the in-vivo neutron activation analysis (IVNAA) of calcium in some parts of tubular limb bones, in the hand, foot and spine is described. The⁴⁸Ca(n, )⁴⁹Ca reaction is used, the gamma-rays of⁴⁹Ca (E=3.08 MeV, T_1/2=8.8 min) are measured. The irradiation is carried out with five of ten²³⁸Pu–Be neutron sources with a source stength of 5·10⁷ n s^–1 each arranged in a bath filled with water. NaI(T1) detectors (from 2 to 4 in number) of 150×100 mm size supplied with lead and shadow shielding are used in the counting unit. The construction of the facility started in 1972 and has been in operation since 1974. It has been used for the examination of patients suffering from limb bone tumors, of children with rickets-like and similar diseases and for studies in space medicine.     

Detector shielding in the study of osteoporosis by in vivo neutron activation analysis

Calcium may be measured in vivo by neutron activation analysis /IVNAA/, observing the 3.1 MeV -ray from the decay of⁴⁹Ca. Normally the detection of this -ray is done in a heavily shielded whole body counter. It is shown that the use of shielding is unnecessary. As a result, the cost of building an IVNAA facility for Ca is very much reduced.     

Small sample in-vivo neutron activation analysis using californium sources

This work describes an in vivo neutron activation analysis facility for small samples, such as rats or human hand, using two 100 g²⁵²Cf neutron sources. The irradiation area is a cylindrical space, of 12 cm diameter and about 15 cm length, with fairly uniform neutron flux distribution. Experimental data on the reproducibility, effects of volume and other conditions for in vivo measurements are given. Comparative atomic absorption data on calcium measurements on rats are reported. The facility is now used for animal experiments as well as human hand irradiations in clinical investigations involving calcium metabolism and bone diseases.     

Calibration strategies for quantifying the Mn content of tooth and bone samples by LA-ICP-MS

There is a growing interest in using biomonitoring of tooth and bone specimens to assess human exposure to manganese (Mn). Information on historical exposure to Mn can be obtained through micro-spatial analysis of such specimens by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The principal aim of this study was to compare several calibration strategies for determining Mn content in tooth and bone by LA-ICP-MS including: (a) a six-point calibration curve based on synthesized hydroxyapatite (HA) materials, and single-point calibrations based on (b) NIST SRM 1400 Bone Ash, (c) NIST SRM 1486 Bone Meal, and (d) NIST SRM 612 Trace Elements in Glass. Performance was similar between different ICP-MS platforms (quadrupole ICP-MS, dynamic reaction cell ICP-MS, and sector field ICP-MS). Data based on calibration using the ⁵⁵Mn count rate were compared to that based on using the ⁵⁵Mn/⁴³Ca count rate ratio to obtain results as the Mn mass fraction. Reasonable performance was obtained by calibration using either SRM 612 or SRM 1400, in combination with the ⁵⁵Mn/⁴³Ca count rate ratio and using either the synthesized HA standards or SRM 1400 as calibrators, combined with ⁵⁵Mn count rate. By contrast, calibration based on SRM 1486 resulted in a systematic low bias. While there are several options for quantifying the Mn content of tooth and bone using LA-ICP-MS, users should be aware of the potential for strong matrix effects that may affect results. Overall, determining the ⁵⁵Mn/⁴³Ca count rate ratio, rather than the mass fraction, may represent a better approach for reporting the content of Mn in tooth and bone by LA-ICP-MS.     

Mapping of neutron flux gradient at NIST reactor to optimize neutron activation analysis of53Mn

Determination of⁵³Mn in meteorites by neutron activation analysis requires a thermal neutron flux high enough to ensure adequate production of⁵⁴Mn from⁵³Mn with a sufficiently low fast neutron component to minimize its production through fast neutron reactions. Thermal and fast neutron fluxes were mapped as a function of sample position within the NIST research reactor in order to determine the optimum position for irradiation of⁵³Mn.     

Determination of232Th in human tissues by pre-concentration neutron activation analysis with yield determination using227Th

The accurate and precise determination of²³²Th in biological samples is very important for the development of biokinetic models for thorium and for improving our knowledge on its distribution in human tissues. Radiochemical neutron activation analysis has long been one of the most sensitive methods for the determination of²³²Th. However, these determinations suffer in reliability because recovery information following the separation is not typically available. This information is particularly important for difficult matrices such as human bone where recoveries may be significantly less than unity. Also, the separation of difficult matrices following neutron activation may involve relatively high personal dose from the co-activated matrix. A novel approach for the determination of radiochemical yield has been developed which employs the use of a readily available, gamma-emitting isotope of thorium,²²⁷Th.²²⁷Th, obtained by radiochemical separation from²²⁷Ac, is added to each, dissolved sample prior to separation and the chemical yield determined by gamma-ray spectrometry following the separation. This pre-concentration step is then followed by neutron activation and the²³²Th determined via²³³Pa using gamma-ray spectrometry. Detection limits were approximately an order of magnitude lower than obtained by alpha-spectrometry.     

Hot atom chemistry in oxyanion targets,part II1: Recoil behaviour of56Mn in permanganates

Fractional precipitation techniques have been utilized to separate the lower valent and parent forms of⁵⁶Mn in permanganate targets and an attempt is made to study a few aspects of chemical stabilization of recoil⁵⁶Mn in permanganates. Ammonium permanganate, recoil behaviour of which has not been studied previously, is chosen as one of the targets along with the potassium permanganate for initial retention and also for isothermal annealing.⁵⁶Mn initial retentions of about 12% and about 4% are obtained for potassium and ammonium permanganate, respectively, by activation from a Ra–Be neutron source. A usual trend for KMnO₄ and the reduction of recoil fragments by ammonium ions in NH₄MnO₄ are seen through the isothermal annealing study.     

Determination of manganese in ores by activation analysis using a californium-252 neutron source

A²⁵²Cf neutron source has been used to analyse manganese in ores such as pyrolusite, rodonite (manganese silicate) and blends used in dry-batteries. Samples with about 150 mg and standards of manganese dioxide were irradiated for about 20 min and counted using a well-type NaI(Tl) scintillation counter and scaler, with or without pulse-height discriminator between the detector and the scaler. The interferences of nuclear reactions⁵⁶Fe(n,p)⁵⁶Mn and⁵⁹Co(n,α)⁵⁶Mn were studied, as well as problems in connection with neutron shadowing during irradiation, gamma-rays attenuation during counting and influence of granulometry of samples. Some of the samples were also analysed by wet-chemical method (sodium bismuthate) in order to compare results.     

Anion exchange behaviour of the transplutonium elements in hydrochloric acid-alcohol media at elevated temperature

The use of instrumental neutron activation analysis (INAA) in determining selected elements in biological materials has been reported by numerous authors. Some of these have detailed the use of INAA to determine an elemental analysis in tobaccos of various geographical origins. This paper describes the first use of INAA to measure the distribution of selected inorganic elements within the tobacco leaf at a single plant stalk position for one tobacco curing routine. Three replicate plots of a common bright tobacco cultivar were grown under normal cultural conditions characteristic for the bright variety. The tobacco leaves were sampled at selected positions in the leaf. The brigh tobacco was cured in a conventional flue-curing barn using standard practices. Immediately after collection, each individual sample was freeze-dried, crushed and sampled. The leaf midrib samples were prepared using a similar procedure. A subsample of about 100 mg was taken from each sample, sealed in a polyethylene bag, irradiated in a thermal neutron flux of 2×10¹⁷ n·m^–2·s^–1 in a pneumatic rabbit system, and subsequently counted to obtain the reported data. A standard reference material was used as a comparator to yield relative elemental concentrations for Ca, Mg, Mn, Na, K, Cl and Br. The data show that chlorine, potassium, sodium and calcium have definite concentration trends within the tobacco leaf. The data also show that some elements, e.g. Mn, were more uniformly distributed throughout the leaf.     

Experimental and Monte Carlo simulation on new manganese bath facility for absolute neutron source emission rate measurement at ENEA-INMRI

This work deals with the absolute measurement of the neutron emission rate from a ²⁴¹Am–Be source by means of the manganese sulphate bath technique, which is the principal method for the absolute determination of the neutron emission rate from radionuclide neutron sources. The facility consists of a spherical container filled with an aqueous solution of manganese sulphate with a ²⁴¹Am–Be neutron source placed at the center. As well known, neutrons from the source, after having been thermalized by the aqueous solution, undergo neutron capture by hydrogen, manganese, sulphur, and oxygen nuclei, thus inducing a certain activity to the solution. Subsequent gamma spectrometry measurements of ⁵⁶Mn activity generated by ⁵⁵Mn neutron activation allows to determine the neutron emission rate of the source, The experimental activity has involved a variety of measurement techniques and calculation procedures, ranging from neutron reactor activation to liquid scintillation counting and Monte Carlo calculations. Neutron activations of ⁵⁵Mn samples has been carried out with the TRIGA reactor of the ENEA-Casaccia Research Centre, and ⁵⁶Mn activated samples were subsequently characterized by liquid scintillation counting, in order to obtain reference standards for the calibration of the NaI(Tl) scintillation detectors utilized to record gamma-ray emission from ⁵⁶Mn. Monte Carlo calculations, carried out by the MCNPX code, were required to calculate neutron transport within the sulphate manganese bath, in particular to determine ⁵⁵Mn neutron capture probability, and (n, α) and (n, p) concurrent reactions, as well as the neutron leakage. Such a procedure has allowed to maintaining the neutron emission rate uncertainty well below 1 %. All the measurements have been carried out at the ENEA-Casaccia Research Centre by the Italian National Institute of Ionizing Radiation Metrology.     

In vivo measurement of the Ca/P ratio by local activation with isotopic neutron sources

In connection with the study and the treatment of generalised demineralising bone diseases, the amount of phosphorus and calcium has been determined in the hand by “in vivo” neutron activation analysis using²⁵²Cf and²³⁸Pu−Be isotopic neutron sources. The statistical accuracy of the induced radioactivity measurement carried out on the hand of a normal subject is about 2% for P and Ca, while the standard deviation over a series of 10 analyses performed on a same phantom remains within 3% for both P and Ca. The results are normalized and expressed in grams of P or Ca per cm³ of bone. The values observed on a group of 55 normal subjects and on some osteoporotic patients are given.     

Preliminary study of trace elements in human brain tumor tissues by instrumental neutron activation analysis

Elemental profiles of brain tumor tissues from 15 patients of astrocytomas (grade I–III) and normal human brain tissues of 23 male age matched autopsies as controls have been studied by instrumental neutron activation analysis. The SLOWPOKE reactor with a thermal neutron flux of 8·10¹¹n·cm^–2·s^–1 and swimming pool type reactor with a thermal neutron flux of 1·10¹³n·cm^–2·s^–1 were used for short and long irradiation of samples, respectively. Spectrophotometry was only used for analyzing phosphorus. A total of 18 elements Se, Na, K, Br, Cl, Mn, Mg, S, Ca, Cu, Hg, Cr, Fe, Rb, Zn, Co, Sc and P has been determined for this purpose. The reliability of methods has been checked by analyzing biological standard reference materials horse kidney (IAEA H-8) and bovine liver (NBS SRM 1577a). The analytical results showed that compared with the normal brain tissues, concentrations of Ca, Fe, Cu, Zn, Se, Mn, Br and Sc were significantly higher in tumor tissues (P<0.01) and concentrations of Rb, K and P were lower, while no differences for contents of Mg, S, Cr, Hg, Na and Cl were observed. A negative correlation between P and Ca in malignant and normal brain tissues was observed.     

Rapid separation of mercury,arsenic, thallium and chromium species

Radiochemical neutron activation analysis is the only method to determine the galactic cosmic ray (GCR) produced radionuclide⁵³Mn (T=3.8·10⁶) in small meteorite samples. A large number of such samples was analyzed using extremely thermalized neutrons of the DIDO reactor at the KFA Jülich. The detection limit of 10^–14 g/g was recently achieved in our laboratory through the improvement of pre- and postirradiation chemistry. The main purpose of our studies of meteorite finds from Antarctica and the Southwestern United States is to establish their exposure ages up to 12·10⁶ a by means of⁵³Mn. Especially in the case of Antarctic meteorites terrestrial ages up to several 10⁵ years have been observed by combining⁵³Mn and²⁶Al (T=7.2·10⁵ a) measurements.     

Estimation of fast neutron fluence released by the Tokai-mura criticality accident from 54Mn in soils collected from the JCO grounds

To estimate fast neutron fluence released by the JCO criticality accident in Tokai-mura, ⁵⁴Mn, which is produced by the ⁵⁴Fe(n,p)⁵⁴Mn reaction, was determined in soil samples by ultra low background g-ray spectrometry after radiochemical separation. Activities of ⁵⁴Mn, using 30-200 g soil samples were detected in soil samples from 13 points in all directions within a 20 m zone from the precipitation vessel we have used. The levels of ⁵⁴Mn ranged from 0.015 to 2.12 mBq/g soil. By using these data and MCNP, the fast neutron fluences were estimated.     

The determination of silicon in steel by 14-mev neutron activation analysis

A fast (2–5 min) non-destructive determination of silicon in steel by 14-MeV neutron activation is described. The 1.78-MeV ²⁸Al activity, induced by the reaction ²⁸Si(n,p)²⁸Al, is counted on a NaI(Tl) detector. An oxygen flux monitor is used to normalise to the same neutron flux.Two methods are described to correct for the ⁵⁶Mn activity (2.58 h), induced into the iron matrix via ⁵⁶Fe(n,p)⁵⁶Mn. Nuclear interferences of phosphorus and aluminium have been examined. Special attention has been paid to stainless steels. A sensitivity of 0.02 to 0.05% of silicon is obtained. The precision is 2 to 3% for steels containing above 1% silicon, and 7% for 0.1% of silicon.     

Impact of In-Vivo Neutron Activation and Related Techniques in the Understanding and Treatment of Bone Diseases of the Elderly

In-vivo neutron activation analysis (IVNAA) has been used in this laboratory, approximately for the past twenty years, to determine the bone status of humans. For this purpose, the total body calcium (TBCa) is assayed and that is indicative of the bone mineral concentration of the individual. We have effectively used this method to diagnose, understand and monitor the treatment of osteoporosis among elderly women, particularly in post-menopausal women. This paper summarizes the technique and our experience in dealing with osteoporosis.     

Internal standard activation analysis of silicon in steel

Non-destructive 14-MeV neutron activation analysis for silicon in steel has been applied with ⁵⁶Mn as internal standard.⁵⁶Mn is formed from the iron matrix via the ⁵⁶Fe(n,p)⁵⁶Mn reaction. Several methods of internal standardisation via⁵⁶Mn are discussed. The 0.84-MeV photopeak of ⁵⁶Mn is recommended if steel samples of about the same composition are to be analysed. Chemically analysed steel samples are used as silicon standards. A precision of 0.7% was obtained for an analysis plus standardisation time of 13 min. Special attention was paid to interferences produced by concentration changes of impurity elements. Several possible sources of errors were investigated.     

Isotopic ratios of129I/127I in mammalian thyroid glands in Japan

The isotopic ratios of¹²⁹I/¹²⁷I in cattle thyroid glands collected from various areas of Japan were measured by neutron activation analysis with combustion pre-treatment. Pig and human thyroid glands were also analyzed by the same method. The iodine isotopic ratio in cattle thyroid glands in Japan is comparable with that observed in Europe. The isotopic ratio in human thyroid glands in Japan is remarkably lower than that in Europe, which has been reported to be comparable to that of cattle. The isotopic ratio in pig thyroid glands is also lower than that in cattle.     

INAA application in the age dynamics assessment of Ca, Cl, K, Mg, Mn, Na, P and Sr in the cortical bone of human femoral neck

The effect of age and sex on eight elements in cortical bone of femoral neck of 78 relatively healthy 15-55 years old women (n = 33) and men (n = 45) was studied. Mass fraction of Ca, Cl, K, Mg, Mn, Na, P, and Sr in intact bone samples were determined by instrumental neutron activation analysis using short-lived radionuclides. The obtained results were in good agreement with the literature data with the exception of Mn and Sr. The mean value of Mn mass fraction was an order of magnitude lower and Sr mean mass fraction was in 1.5-5 times higher than the reference values. No age- and sex-related differences in bone composition were detected. This revised version was published online in August 2006 with corrections to the Cover Date.