Study of the dose and distribution of technetium-99m-MDP in various bones and tissues

The variation with time of the percentage uptake and retention of injected activity per gram of various bones and organs of rat were measured as part of a series of experiments designed to study the distribution and localization of the 99Tcsup(m)-MDP bone imaging complex. These values were used retrospectively to estimate the radiation dose absorbed in the human body. Although the results obtained were in fairly good agreement with those reported in the literature, those for bone were significantly higher, and therefore the calculation for the latter was repeated this time making use of in vivo dog data where the radiopharmaceutical was directly injected into the nutrient artery to the tibia. The absorbed bone radiation dose from the canine data was found to be in very good agreement with the value previously calculated from rat data. It was interesting to observe that percentage uptake and retention of injected activity per gram of various rat bones at two hours correlates with the inverse of the percentage of trabecular mineralization of the bone. The usual difficulties encountered in calculating blood dose values are also expressed. (author)