Physics in Medicine and Biology · 1984 · 72 citations · 17 references
EngineeringNutritionNutritional SciencesHuman NutritionNuclear InstrumentationRadiation MeasurementBody CompositionDosimetry InstrumentationGamma-ray SpectroscopyNeutron Activation AnalysisNutritional AssessmentNutritional Status AssessmentBody Composition MeasurementDose Equivalent MeasurementGamma SpectroscopyNeutron ActivationNeutron Equivalent DosePrompt Gamma Activation AnalysisPrompt Gamma Neutron Activation AnalysisPrompt Gamma Spectroscopy
The quantitative assessment of protein, water, and fat is essential for studying metabolic and nutritional issues in critically ill patients in intensive care. The study describes constructing and calibrating a bilateral neutron irradiation facility using two 281 GBq 238Pu‑Be sources. Patients were scanned for 36 min while prompt gamma spectra were collected from two NaI(Tl) detectors on either side, and a nitrogen‑to‑hydrogen count ratio corrected for body habitus and background was used to estimate protein. The combined neutron‑prompt‑gamma and tritium‑dilution method estimates protein, water, and fat with 4.2 %, 1.5 %, and 6.3 % precision, respectively, at a dose below 0.5 mSv.
The quantitative assessment of the nutritionally-important components of body composition (protein, water and fat), provides a basic tool for research into the metabolic and nutritional problems of critically ill patients requiring intensive care. The construction and calibration of a facility that provides bilateral irradiation of patients with neutrons from two 281 GBq 238Pu-Be source is described. Patients are scanned over a 36 min period, and composite prompt gamma -spectra are collected from two 5 in*4 in NaI(Tl) detectors, placed on either side of the patient, using a conventional spectroscopy analysis system. A ratio of nitrogen to hydrogen counts corrected for body habitus and background is derived, from which protein can be estimated. This technique, combined with the measurement of water by tritium dilution, enables protein, water and fat to be estimated with precisions of 4.2%, 1.5% and 6.3% respectively, for a total dose equivalent (neutrons and tritium betas) of less than 0.5 mSv per examination.
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