Advances in Computational Models of Bone Marrow Radiation Dosimetry Through Microimaging

Date(s) - 12/06/2010
5:00 pm - 6:00 pm

Dr. Wesley Bolch (Nuclear Science)

The tissues of the hematopoietic bone marrow are among the most radiosensitive tissues of the human body for both stochastic cancer risk and acute deterministic effects.  As a consequence, bone marrow toxicity is frequently an issue in radionuclide therapies, and strategies must be in place to either avoid dose-limiting levels of marrow irradiation, or provide for stem cell rescue.  Dose-response models are also needed to allow the nuclear medicine physician to anticipate the onset of marrow toxicity, and for these models to be robust, accurate and patient-specific estimates of marrow dose must also be calculated.  Due to the highly heterogeneous and microscopic features of trabecular spongiosa regions of the human skeleton, this level of dosimetry is a tall order.  The 3D shape of bone trabeculae and the adjacent marrow cavities must be fully modeled in all regions of the skeleton, and patient-specific features of skeletal stature, bone mineral status, and marrow fat content should – ideally – be fully known and folded into the dose assessment.  In this presentation, we will review the history bone dosimetry models – starting with the early studies at the University of Leeds in the UK, and ending with recent work performed at the University of Florida, the latter involving ex-vivo CT and microCT imaging of cadaveric bone, MR mapping of marrow cellularity, and spatial mapping of the hematopoietic stem and progenitor cells across the marrow cavities.  The work performed at UF is quickly becoming the international standard for marrow dosimetry for use in both medical dose assessments and those for radiological protection of workers and members of the general public.