Dosimetry in intrathecal radiogold therapy. 4

The radiation dose absorbed depends on the distribution of the 198Au colloid, its physical properties and the applied activity as well as on the anatomy of the source and the target. These methodic fundamentals were studied. Assuming a homogeneous distribution on the surface of the source organ the radiopharmaceutical in 24 children suffering from acute leukemia the effective dose was calculated to be (296 +- 137 rads) for the intracranial subarachnoid space, (1648 +- 823 rads) for the spinal cord and (35 +- 26 rads) for the liver following administration of 1.5 - 3 mCi 198Au colloid. The sources of error caused by the complicated anatomy of the CSF space and by differences in the detailed distribution of the 198Au colloid are discussed. The advantages of this method - good compatibility and intactness of the nervous tissues - can be explained by the sharp decrease of the dose absorbed. (author)