Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Includes bibliographical references.

<p>The non-invasive measurements of the mass of bone is a clinically relevant problem. The bone is one component of a composite system. At the spine it may include fat, lean and bone material. At a hip prosthesis it may include soft tissue, bone material and metal. The measurements of the attenuation of photons of different energies can be used to determine the mass of one or all of the components of the composite system.</p> <p>The first system is currently measured using only two photon energies by assuming that it is a two component system. A model was developed which predicts the effect of the third component, fat, and was validated using phantom measurements. Typical parameters for the volume and spatial distribution of fat in vivo were determined using CT scans. In combination with the model a median error if 8% is introduced by the third component. The feasibility of using a third energy to correct for the error was investigated. A model for the variance of the bone measurement normalized to emitted photon flux was developed. The optimal set of photon energies yielded a minimum value for the variance. However, this variance was excessively high, requiring a radiation dose 3000 times that for dual photon absortiometry.</p> <p>For the second system a triple photon absorptiometry technique was developed using the isotopes 203-Hg and 141-Ce. The technique was shown to be valid, but the variance was high due to cross-over of high energy photons in the detector and by scattering. In order to make measurements with a precision of 1%, counting times of 70 hours are required. Monte Carlo simulations were performed to determine the optimal geometry to reduce cross-over cannot be reduced sufficiently with 203-Hg and 141-Ce. A three isotope source is required to make clinical bone measurements at a prosthesis.</p> / Thesis / Doctor of Philosophy (PhD)

Thesis (doctoral)--Katholieke Universiteit te Nijmegen.

Thesis (doctoral)--Katholieke Universiteit te Nijmegen.

The non-invasive measurement of the mass of bone is a clinically relevant problem. The bone is one component of a composite system. At the spine it may include fat, lean and bone mineral. At a hip prosthesis it may include soft tissue, bone mineral and metal. The measurement of the attenuation of photons of different energies can be used to determine the mass of one or all of the components of the composite system. The first system is currently measured using only two photon energies by assuming that it is a two component system. A model was developed which predicts the effect of the third component, fat, and was validated using phantom measurements. Typical parameters for the volume and spatial distribution of fat 𝘪𝘯 𝘷𝘪𝘷𝘰 were determined using CT scans. In combination with the model a median error of 8% is introduced by the third component. The feasibility of using a third energy to correct for the error was investigated. A model for the variance of the bone measurement normalized to emitted photon flux was developed. The optimal set of photon energies yielded a minimum value for the variance. However, this variance was excessively high, requiring a radiation dose 3000 times that for dual photon absortiometry. For the second system a triple photon absorptiometry technique was developed using the isotopes 203-Hg and 141-Ce. The technique was shown to be valid, but the variance was high due to cross-over of high energy photons in the detector and by scattering. In order to make measurements with a precision of 1%, counting times of 70 hours are required. Monte Carlo simulations were performed to determine the optimal geometry to reduce cross-over from scattering. However, cross-over cannot be reduced sufficiently with 203-Hg and 141-Ce. A three isotope source is required to make clinical bone measurements at a prosthesis. / Thesis / Doctor of Philosophy (PhD)

Thesis (M.S..)--Cornell University, May, 2008. / Vita. Includes bibliographical references (leaves 77-92).

Bone disease and metabolic bone disorders are characterized by decrease in bone mineral content (BMC) and the vertebrae are primarily affected in osteoporosis. Thus it is essential to monitor changes in BMC due to disease, growth or therapy. Dual photon absorptiometry (DPA) is as yet the most efficient method for BMC determination in the lumbar vertebrae; most previous investigators have used ¹⁵³Gd which is generally accepted as possessing the ideal dual photon energy combination. Davis and Webber (1978) developed a method for routine production of ¹⁵³Sm which emits photons of nearly the same energy as ¹⁵³Gd and suggested its use in DPA. In the present study using ¹⁵³Sm, measurements with aluminum standards immersed in water resulted in errors of 4% and 4.5% in accuracy and precision respectively for mass of Al in the range 0.4-1.8 g.cm⁻². These results were obtained using different volumes of water, verifying that bone mineral mass determined by this method is independent of soft tissue content. Experiments with bone mineral phantoms gave values which correlated highly (r=0.97) with results obtained on a commercially available clinical densitometer using ¹²⁵I. Considering that these results are comparable with those obtained earlier using ¹⁵³Gd, that ¹⁵³Gd is scarcely available and several hundred times the cost, ¹⁵³Sm promises to be the potential source for routine clinical measurement of osteopenia in the lumbar spine by DPA. However, further invitro and invivo studies are necessary before it can be used regularly in nuclear medicine departments. / Thesis / Master of Engineering (ME)

No description available.

PURPOSE: To establish the reliability of anthropometric and dual energy X-ray absorptiometry(DXA) techniques used to assess percent body fat (% BF)in female athletes; to establish limits for detecting the smallest real change in % BF associated with anthropometric and DXA testing;to evaluate the validity of commonly used % BF prediction equations recommended by national certification programs along with equations derived from Multicompartment (MC), and DXA, in female athletes; and to create a new DXA based regression equation for elite female athletes. METHODS:Female athletes aged 17-31 were recruited into the study and participated in the establishment of anthropometric reliability (N=20), DXA reliability (N=32), and /or skinfold validity (N=95) testing. Anthropometric testing consisted of measurements of skinfolds,circumferences, and breadths. DXA measurements were conducted using a GE Lunar Prodigy DXA which served as the criterion measure (% BF DXA). RESULTS: Excellent reliability for both anthropometric sum5 skinfolds (ICC= .997, %TEM=0.9 %) and DXA (ICC =.996, CV =1.13% BF) techniques allows for detection of smallest real differences of 2.2 mm and 721g in summed skinfolds (sum5) and fat mass respectively. The DXA based equation of Ball et al.(2004) displayed the greatest validity of existing equations R=.874, total error (TE) 2.9% BF, and Bland Altman Limits of Agreement -4.7to 6.5 % BF. The newly created regression equation demonstrated a non-linear characteristic and displayed similar predictive ability R= .840, TE 3.0%BF, and Bland Altman Limits of Agreement of -6.1to 6.1 % BF. CONCLUSIONS: Anthropometric equations derived from various criteria yielded dissimilar results. Long utilized popular equations advocated in national accreditation schemes (ACSM, CSEP) show considerable bias compared to modern values obtained by current DXA technology. A new regression equation was created for female Canadian athletes 17-31yrs of age using skinfolds taught in the Canadian national professional certification program (CSEP).

PURPOSE: To establish the reliability of anthropometric and dual energy X-ray absorptiometry(DXA) techniques used to assess percent body fat (% BF)in female athletes; to establish limits for detecting the smallest real change in % BF associated with anthropometric and DXA testing;to evaluate the validity of commonly used % BF prediction equations recommended by national certification programs along with equations derived from Multicompartment (MC), and DXA, in female athletes; and to create a new DXA based regression equation for elite female athletes. METHODS:Female athletes aged 17-31 were recruited into the study and participated in the establishment of anthropometric reliability (N=20), DXA reliability (N=32), and /or skinfold validity (N=95) testing. Anthropometric testing consisted of measurements of skinfolds,circumferences, and breadths. DXA measurements were conducted using a GE Lunar Prodigy DXA which served as the criterion measure (% BF DXA). RESULTS: Excellent reliability for both anthropometric sum5 skinfolds (ICC= .997, %TEM=0.9 %) and DXA (ICC =.996, CV =1.13% BF) techniques allows for detection of smallest real differences of 2.2 mm and 721g in summed skinfolds (sum5) and fat mass respectively. The DXA based equation of Ball et al.(2004) displayed the greatest validity of existing equations R=.874, total error (TE) 2.9% BF, and Bland Altman Limits of Agreement -4.7to 6.5 % BF. The newly created regression equation demonstrated a non-linear characteristic and displayed similar predictive ability R= .840, TE 3.0%BF, and Bland Altman Limits of Agreement of -6.1to 6.1 % BF. CONCLUSIONS: Anthropometric equations derived from various criteria yielded dissimilar results. Long utilized popular equations advocated in national accreditation schemes (ACSM, CSEP) show considerable bias compared to modern values obtained by current DXA technology. A new regression equation was created for female Canadian athletes 17-31yrs of age using skinfolds taught in the Canadian national professional certification program (CSEP).