Detection of lead via lead-207m using cyclic activation and a modified sum-coincidence system.
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Activation Analysis↗
Biomedical subjects
N M Spyrou
Publications and source records attributed to N M Spyrou.
Tomography and elemental analysis of biological systems.
The various forms of tomography, expressed as transmission and emission modes using gamma rays and neutrons, are generally discussed in terms of providing information nondestructively about the distribution of elemental composition in a plane through an object. The combination of the principles of tomography with neutron activation analysis is the basis for neutron-induced gamma-ray emission tomography. The concept of detection limit in induced gamma-ray emission tomography, as proposed, incorporates a further factor that is a measure of the quality of the image produced. A specific example is given for the elemental analysis and imaging of a bone specimen.
Gamma Rays↗
Fluorine concentrations in bone biopsy samples determined by proton-induced gamma-ray emission and cyclic neutron activation.
Fluorine concentrations in bone biopsy samples taken from the iliac crest of subjects, divided into four groups depending on the length of dialysis treatment, and aluminium levels in blood and bone pathology, in terms of osteoporosis, were determined by two instrumental methods. Proton-induced gamma-ray emission (PIGE), making use of the resonance reaction of 19F(p, alpha gamma)16O at 872 keV, and cyclic neutron activation analysis (CNAA), using the 19F(n, gamma)20F reaction in a reactor irradiation facility, were employed. Rutherford backscattering (RBS) was used to calculate the volume, and, hence, mass of the sample excited in PIGE by determining the major element composition of the samples in order to express results in terms of concentration. From this preliminary investigation, a relationship is suggested between fluorine concentrations in bone and aluminium levels in the system.
Aluminum↗
Major and trace element concentration differences between the right and left hemispheres of the "normal' human brain.
The brain can be divided into many anatomical regions, and the minor and trace element distribution across these regions has been shown to be heterogeneous. The various functions of the brain such as memory and language have been associated with different brain regions, and attempts to correlate brain function with elemental composition have been made. Establishing "normal" concentration values is a complex task due to the variability of factors such as age, sex, dietary intake, environmental exposure, and smoking habits. In establishing the elemental concentration of a particular brain region, a mean value from the right and left hemispheres of different brains is often used. This is usually due to the lack of availability for analysis of the same brain regions from both hemispheres of one individual. However, it is known that the right and left hemispheres have different functions. Thus, it may be expected that they may have different trace element concentrations as well. In this study 13 brain regions were sampled from both hemispheres of six elderly individuals, and their major element composition was determined by Rutherford backscattering (RBS) analysis, whereas the minor and trace element concentrations were obtained by particle induced X-ray emission (PIXE) analysis.
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