In Reply.—The data presented by Garn and Poznanski are interesting. However, I would like to point out a few benefits of photon absorptiometry compared with radiogrammetry. The dose of radiation in photon absorptiometry is comparable with that currently used in low-level radiogrammetry. However, the scan is very narrow, and only a one-eighth-in-wide section of the forearm is exposed. This contrasts to radiogrammetry, in which the entire hand is exposed. Photon absorptiometry is underutilized in surveys. The equipment itself is easily transported and would be ideal for field measurements, especially compared with the difficulty of conducting field surveys with a portable x-ray machine.
I am also curious about the variation of the radiogrammetry method that the authors describe—the SDs that they observed and the coefficient of variation. It has been previously reported1 that the accuracy of this method is decreased significantly by soft tissue and that the measurement of