Induced nuclear reactions: processes – systems – and elements – Nuclear transmutation – By neutron bombardment
Reexamination Certificate
1997-09-16
2001-11-06
Behrend, Harvey E. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Nuclear transmutation
By neutron bombardment
C250S390040, C250S390060
Reexamination Certificate
active
06314152
ABSTRACT:
BACKGROUND OF THE INVENTION
Body composition and specifically percent body fat detection is relevant in a number of different contexts. For the individual, it can be used as a predictor of cardiovascular disease. In studies, it is useful to characterize and determine the mechanisms of sarcopenia, defined as the muscle loss with age, and other catabolic conditions. For example, in populations undergoing drug therapy to stall or reverse the effects of wasting diseases such as AIDS, body composition assessment can be used to quantify the efficacy of those drugs.
A number of techniques exist for detecting percent body fat in animals. Hydrodensitometry, bioelectrical impedance analysis (BIA), and dual energy absorptiometry (DXA) are examples based upon the influence of body fat or hydration on physical properties of the body, such as density, electrical impedance, and photon attenuation properties. Other techniques for single compartment body composition analysis are available, some of which are correlated to percent body fat. Body water can be measured by isotope dilution using D
2
O,
3
H
2
O or H
2
18
O. Body protein is measured by direct measurement of total body nitrogen (TBN) using prompt-gamma neutron activation. Body cell mass, a compartment overlapping with both water and protein, is measured by gamma counting of the natural radioactivity of the body's
40
K.
SUMMARY OF THE INVENTION
In general these existing techniques for determining percent body fat, although being widely available and in most cases inexpensive, can sometimes fail to yield the accuracy required. In many cases, their assessment of body composition is indirect and subject to a series of assumptions that may vary in their validity across populations of diseased patients. In contrast, the most reliable method is Hydrodensitometry which provides a direct application of the two compartment model using assumptions on the densities of lean and fat tissue. This technique, however, is many times inappropriate, especially in very diseased and older patients since it requires immersion of the patient. Moreover, it typically requires lung volume tests.
The present invention is directed to a technique for determining percent body fat using neutron inelastic scattering. It relies on a correlation between a carbon-oxygen ratio in the body and the percent body fat with corrections made for a level of patient hydration in the lean tissue. This technique provides accuracy approaching that achieved with Hydrodensitometry with only small radiation doses between 5 and 20 millirem, but without any requirements for immersion. It can also measure regional body fat and fat distribution, which is generally not possible using Hydrodensitometry.
In general according to one aspect, the invention features a method for determining proportion of body fat in an animal body. The method includes determining a proportion of body fat as a function of a ratio of carbon and oxygen and levels of hydration. The animal body is then irradiated with neutrons having sufficient energy to inelastically scatter off of carbon and oxygen. The resulting gamma rays are detected and counted. The ratio of the detected gamma rays and hydration are then related to a proportion of fat in the animal body.
In specific embodiments, the level of hydration is preferably directly measured using isotope dilution, for example. Alternatively, the hydration may be estimated based upon the diseased state of the animal body and population statistics relating hydration to the diseased state. Finally, previous hydration tests on a specific individual may be used. However, the technique is not particularly sensitive to the level of hydration.
In other aspects of the embodiment, the proportion of body fat as the function of the ratio of carbon and oxygen includes estimating a portion of detected oxygen that results from water, protein, and fat, and possibly including bone and glycogen, and the corresponding stoichiometries. Similarly, a portion of detected carbon that results from protein and fat is estimated, with the possible inclusion of bone and glycogen.
Where relevant, gamma rays from different regions of the animal body may be detected and separately accounted. This enables the determination of the proportion of fat in those regions.
According to another aspect, the invention features system for determining proportion of body fat in an animal body. The system includes a neutron source, such as a D-T generator, for generating and directing neutrons at the animal body. A gamma ray detector (preferably BGO) detects gamma rays indicative of excited carbon and oxygen atomic nuclei. The controller receives an indication of the detected gamma rays from the gamma ray detector and an input level of hydration for the animal body and determines a proportion of body fat for the animal body.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.
REFERENCES:
Nucl. Instrum. and Methods in Physics Research A, vol. 353, pp. 444-447, Kehayias et al (I), 1994.*
Proc. SPIE—Int. Soc. Opt. Eng., vol. 2339, pp. 524-528, Kehayias et al (II), 1994.*
Biol. Trace Elem. Res., vol. 26-07, pp. 423-428, Mitra et al, 1990.*
Basic Life Sciences, vol. 60, pp. 49-52, Kehayis et al III, 1993.*
Medical Physics, vol. 20, No. 4, pp. 1129-1134, Sutcliffe et al, Jul./Aug. 1993.*
The American J. of Clinical Nutrition, vol. 61, No. 5, pp. 1110−, Aloia et al (I), May 1995.*
BNL-49461, pp. 1-6, Ma et al, 1993.*
Phys. Med. Biol., vol. 29, No. 3, pp. 209-218, Vartsky et al, 1984.*
Int. S. Nucl. Med. Biol., vol. 4, No. 2, pp. 133-137, Biggin et al, 1977.*
European J. of Clinical Nutrition, vol. 47, pp. 863-874, Ryde et al (I), 1993.*
Metabolism, vol. 34, No. 6, pp. 509-518, Streat et al, 1985.*
Basic Life Sciences, vol. 60, pp. 367-370, Ryde et al (II), 1993.*
J. of Nucl. Med., vol. 36, No. 8, pp. 1392-1397, Aloia et al (II), Aug. 1995.*
Am. J. Physiol: Endocrinology and Metabolism, vol. 24, No. 2, pp. E190-E198, Heymsfield et al, Aug. 1991.*
Phys. Med. Biol., vol. 27, No. 6, pp. 805-817, Kyere et al, 1982.*
J. Radioanal. Nucl. Chem., vol. 160, No. 1, pp. 159-168, Ellis et al, 1992.*
J.J. Kehayias et al (IV) and H. Zhuang, “Use of the Zetatron D-T Neutron Generator for the Simultaneous Measurement of Carbon, Oxygen, and Hydrogen in vivo in Humans,” Nuclear Instruments and Methods in Physics Research Elsevier Science Publishers B.V., NIMB B79 (1993) 555-559.
Joseph J.Kehayias et al (V), “In Vivo Determination of Body Fat by Measuring Total Body Carbon1−3, ”Am J Clin Nutr1991; 53:1339-44.
Richard B. Mazess et al., “Dual-Energy X-ray Absorptiometry for Total-Body and Regional Bone-Mineral and Soft-Tissue Composition1−2,”Am J Clin Nutr1990; 51:1106-12.
Kenneth R. Foster and Henry C. Lukaski, “Whole-Body Impedance—What Does it Measure1−2,”Am J Clin Nutr1996; 64(suppl.):388S-96S.
Behrend Harvey E.
Hamilton Brook Smith & Reynolds P.C.
Trustees of Tufts College
LandOfFree
Body composition detection using neutron inelastic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Body composition detection using neutron inelastic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Body composition detection using neutron inelastic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2586599