Fat to Muscle Ratio Measurements with Dual Energy X Ray Absorbtiometry
  Accurate measurement of the fat-to-muscle ratio in animal model is important for obesity research. An efficient way to measure the fat to muscle ratio in animal model using dual-energy absorptiometry is presented in this paper. A radioactive source exciting x-ray fluorescence from a target material is used to provide the two x-ray energies needed. The x-rays, after transmitting through the sample, are measured with an energy-sensitive Ge detector. Phantoms and specimens were measured. The results showed that the method was sensitive to the fat to muscle ratios with good linearity. A standard deviation of a few percent in the fat to muscle ratio could be observed with the x-ray dose of 0.001 mGy. 
A. Chen, A. Wang, C. Broadbent, J. Zhong, A. Dilmanian, F. Zafonte,   and Z. Zhong
physics.med-ph