1. In Vivo Neutron Activation Analysis
by Sarah Steinmetz and Amber Brouillette

2. Overview
What it is:
a group of related techniques involving in vivo neutron activation analysis (NAA) that estimate the amount of a range of chemical elements living in the human body
most other body composition studies generate tissue volume or density, but not chemical composition

3. Overview
Nearly all the major elements present in the body can be analyzed by in vivo NAA
including hydrogen, oxygen, carbon, nitrogen, calcium, phosphorus, sodium and chlorine
Some procedures measure specific elements that have concentrated in organs
cadmium, mercury and iodine
Mostly used to determine total body calcium and total body nitrogen

4. How it Measures Body Composition
Through different processes of radiation
atoms in the body are exposed to a neutron flux and and undergo nuclear reactions
when the atom catches a neutron it becomes radioactive and emits a signal
in gamma waves
special detectors sense the signal and are then analyzed

5. How it Measures Body Composition
Total body nitrogen by in vivo NAA
bombard patient in supine position with a low neutron flux from PuBe sources/cyclotron/neutron generator
N is converted to an excited state, and then quickly decays to its ground state releasing gamma waves
detected by sodium iodide detectors
detected gamma waves are proportional to the mass of total body nitrogen=measure of total body protein

6. Appropriate Population
Living Human Subjects
Ill/Chronic nutritional deprivation (HIV/AIDS patients)
Elderly Patients
Critically Injured

7. Appropriate Population, Cont.
This technique bypasses constancy assumptions that are central to traditional and indirect methods and that plague the extension of body composition methods of certain subjects in whom these assumptions are manifestly incorrect
Constancy assumption -- intervention group against placebo group in historical data assumed to be the same in current data/study

8. Strength
More information can be gained from total body neutron activation than by any other available method

9. Weakness High cost Need of skilled operator Lack of mobility
Use of radiation

11. Test Question
What is the biggest deterrent from using in vivo neutron activation analysis?

12. Answer
Cost
Even though there have been some concerns about possible radiation exposure, the risk is no greater than radiation seen in “every day” risk

13. References https://www.bcm.edu/bodycomplab/ivnamainpage.htm
Ma, Kaizong, Donald P. Kotler, Jack Wang, John C. Thornton, Ruimei Ma, and Richard N. Pierson. "Reliability of in Vivo
Neutron Activation Analysis for Measuring Body Composition: Comparisons with Tracer Dilution and
Dual-energy X-ray Absorptiometry." Journal of Laboratory and Clinical Medicine (1996): Web.
Lukaski, Henry C. "Methods for the Assessment of Human Body Composition:Traditional and New." The American
Journal of Clinical Nutrition 46 (1987): Web. 8 Nov
Ellis, Kenneth J. "American Physiological Society." Human Body Composition: In Vivo Methods 80.2 (2000):
Web. 8 Nov