Biomedical subjects
Publications and source records attributed to G I Harris.
The DANTE pulse sequence was modified to produce selective resonance saturation similar to that produced by the continuous wave (CW) technique. A combined DANTE and CW saturation technique can be used to perform multisite saturation transfer experiments because of the similar saturation produced by the two techniques.
A significant proportion of diagnostic medical procedures are used in response to public or private policy rather than in response to an individual patient-physician interaction. We have studied the system whereby such policies are developed and implemented in the case of employment-related chest and lumbar spine roentgenograms, which were found to account for about 11% of the total use of diagnostic radiographs in the state of Michigan. We observed that factors influencing formulation of policy are diverse and largely nonmedical, organizational policies developed in similar environments are often very dissimilar and are highly subject to external influence, and perceptions of policy success and examination utility are typically subjective and uncertain. It is concluded that considerable opportunity exists to enhance the efficacy of such radiographic examinations through leverage provided by their policy-driven nature.
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The physical decay characteristics of the short-lived radionuclide Ta-178 (half-life 9.3 min) appear to be suitable for use in conjunction with low-energy detection systems such as the multiwire proportional camera. This camera is inefficient for emissions with energies greater than 100 keV. The gamma-ray spectrum of Ta-178 is dominated by the characteristic hafnium x-rays (55--65 keV), emitted as a result of electron-capture decay. The parent nuclide, W-178 (half-life 21.7 d), was produced in the Michigan State University cyclotron by proton bombardment of stacked natural tantalum-foil targets. Optimum production was found to occur with an incident proton energy of 34 MeV at an effective activity of 1.1 mCi/muA-hr per MeV of target thickness. Tungsten-178 was chemically separated from the Ta foils with a yield of 98%.
We describe a chemical separation that may form the basis of a generator system for the short-lived radionuclide Ta-178 (T 1/2 = 9 min). The parent nuclide W-178 (T 1/2 = 21.7 days) is loaded on an anion-exchange column and the daughter eluted with a mixture of dilute hydrochloric acid and hydrogen peroxide. The yields of tantalum and the breakthrough of the tungsten parent as a function of the eluting conditions are discussed, and preliminary animal distribution data are presented for various treatments of the eluant solution.
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