[en] Recent technical advances and unique approaches to calibration now allow for improved calibration of in vivo measurement systems. The new approach utilizes Monte Carlo calculational techniques along with a library of Magnetic Resonance images consisting of 32 human or human-like phantoms. The library of whole body images is the largest of its kind currently available and a prime resource for expanded DOE efforts in worker health and safety. This technique will save user facilities time and funds in the calibration of in vivo measurement systems while at the same time allowing greater flexibility in the selection of calibrations appropriate for a subject's physical stature