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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #83162
Title: TOTAL BODY FAT MASS BASED ON THE 4.4 MEV CARBON PEAK IN THE IN VIVO PROMPT-GAMMA SPECTRUM OF THE HUMAN BODY USING 241AM,BE NEUTRONS

Author
item Ellis, Kenneth
item SHYPAILO, ROMAN - BAYLOR COLL. OF MEDICINE

Submitted to: Journal of Radioanalytical and Nuclear Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Various methods have been used to evaluate human body composition to determine the body's fat and fat-free mass, information which is very useful in the field of nutrition. One such method is called in vivo neutron activation analysis, which uses low-dose radiation to provide a chemical profile of the human body. Neutron activation analysis can be used to measure body carbon to assess total body fat. We had already developed a prompt-gamma activation analysis (PGAA) instrument to measure body nitrogen, and we theorized we could also use PGAA to measure the body's carbon content. We ran tests on 33 young women, age 24-40 years. Our results showed this method is effective in measuring body fat, and obtains the same values as those obtained from dual- energy X-ray absorptiometry (DXA, another state-of-the-art technique). However, PGAA has an advantage in that it can measure the body's fat mass at the same time as protein mass. Thus, PGAA can provide two important body composition yardsticks of the nutritional status of an individual. That should prove helpful to nutritionists and scientific investigators in future studies.

Technical Abstract: We examined the feasibility of measuring total body carbon (TBC) based on the 4.4 MeV peak produced by in vivo prompt-gamma activation analysis (PGAA) of the human body when using a 241Am, Be neutron source. TBC was derived on the basis of the ratio of net counts in the 4.4 MeV peak to those in the 2.2 MeV peak from hydrogen, and an estimate of total body hydrogen based on body weight. Preliminary analyses of the PGAA spectra for 33 healthy pre-menopausal women (ages: 24-40 yr) indicated a mean TBC value of 7.1 kg (SD = +/- 4.4 kg), which is consistent with the value reported for a reference adult female. The mean body fat mass obtained by PGAA was 17.1 +/- 6.5 kg, or 27.9% +/- 7.9% of body weight. The values were comparable to those obtained using dual- energy X-ray absorptiometry. An advantage of the PGAA measurement is that total body fat mass can be obtained at the same time as total protein mass. Both body composition indices are useful for the nutritional assessment of an individual.