DISTRIBUTION OF RADIOACTIVE GALLIUM IN THE TEETH AND JAWS OF EXPERIMENTAL ANIMALS

¹ Naval Medical Research Institutte, Bethesda, Md.

Radiogallium in the form of soluble gallium lactate (pH 7.0 to 7.4) was injected subcutaneously into rats and rabbits. The dosage was 0.2 to 0.4 millicuries of Ga⁷² per kilogram of body weight (6 mg./kg.), which is well below the toxic level. The animals were killed in six hours and thin sections (50 to 100 µ) were made of the bone and teeth by cutting with high speed abrasive discs and grinding to the desired thickness against an abrasive wheel. These thin sections were placed next to special x-ray film for 24 to 48 hours. The rays emanating from the radioactive isotope affected the film just as do the rays from an x-ray tube. The developed negatives were compared with transillumination photographs which were subsequently made from the ground sections. By this means it was determined that radiogallium is predominantly deposited in endosteum, periosteum, tooth pulp, and peridontium. There is a moderate deposition in cancellous bone. Cortical bone and the dentin of the root portion of teeth take a barely perceptible amount of radiogallium, whereas coronal dentin and enamel give no indication that any radiogallium is deposited. The main advantages of this method over those using the electroscope or Geiger counter for determining the radioactivity are that fractional portions of teeth and bone are not required, and the visual localization is rapid and effective. The relative distribution of the radioactive substance in each anatomic area is apparent; however, accurate quantitative measurements were not attempted in this study.