Triple photon absorptiometry cannot correct for fat inhomogeneities in lumbar spine bone mineral measurements.

In vivo fat inhomogeneities can cause significant errors in measurements of lumbar spine mineral mass using dual photon absorptiometry. Extension to a triple photon technique to correct for the presence of fat is not possible because of the unacceptable increase of about a factor of 3,000 required in the radiation dose to yield sufficient transmitted photons for adequate precision.