37. Radionucleotide Bone Imaging

When technetium 99m is bound to methylene diphosphonate, the resulting ­compound is called technetium 99m-MDP. Administered intravenously, as much as 60% of this substance will be taken up by the skeleton through a process called chemabsorption by which the tracer is actually incorporated into the calcium hydroxyapatite crystal matrix of bone or other calcium depositions. The remainder of the tracer is excreted via the urinary tract. Gallium, another radioactive material, is not used as a primary agent for bone scans now that MDP bone scanning is available (Fig. 37.1)