A Paired-Image Radiation Transport Model for Skeletal Dosimetry

Toxicity of the hematopoietically active bone marrow continues to be a primary limitation in radionuclide therapies of cancer. Improved techniques for patient-specific skeletal dosimetry are thus crucial to the development of dose–response relationships needed to optimize these therapies (i.e., avoid both marrow toxicity and tumor underdosing). Current clinical methods of skeletal dose assessment rely heavily on a single set of bone and marrow cavity chord-length distributions in which particle energy deposition is tracked within an infinite extent of trabec-ular spongiosa, with no allowance for particle escape to cortical bone. In the present study, we introduce a paired-image radia-tion transport (PIRT) model that can provide a more realistic 3-dimensional geometry for particle transport of the skeletal site at both microscopic and macroscopic levels of its histology. Methods: Ex vivo CT scans were acquired of the lumbar ver