Click here to


Are you sure ?

Yes, do it No, cancel

Microdistribution of Absorbed Dose From Alpha and Beta Emitters Contained Within the Blood Pool in a Bone Marrow Model

J Tranel1*, F Feng2, T A Hope1, S St. James2, (1) Department of Radiology, University of California San Francisco, San Francisco CA(2) Department of Radiation Oncology, University of California San Francisco, San Francisco CA


(Thursday, 7/16/2020) 11:30 AM - 12:30 PM [Eastern Time (GMT-4)]

Room: Track 3

Monte Carlo simulations were performed in an interface model between blood vessel and trabecular bone to quantify energy deposition differences among alpha (²¹¹As, ²²5Ac) and beta (?°Y, ¹77Lu) emitters used in targeted radionuclide therapy (TRT). This region is of interest when the radiation dose to the bone marrow is of concern.

Monte Carlo simulations were performed using GATE. A model with two compartments was assessed: the blood pool (1.06³) and trabecular bone (1.05³). The latter is considered as an organ at-risk. The radionuclide sources were located in the blood pool compartment. The whole energy spectra and daughters were considered for the radionuclides energy emissions. Two geometries were simulated. First, blood pool and trabecular bone interface were parallel in the XY plane and symmetric along the Z axis. Secondly, a model of a cylindrical blood vessel was created, similarly centered in the XY plane.Transverse and radial profiles were analyzed for both configurations.

For the parallel model, absorbed dose from alpha emitters is superior to beta emitters with a factor varying from 125 (²¹¹As vs ¹77Lu) up to 1082 (²²5Ac vs ?°Y). At 75 µm from the interface and in the trabecular bone area, ²²5Ac energy deposition decreases with a factor of 860, ²¹¹As decreases with a factor 18,437. For beta emitters, the decrease is less pronounced, with a factor of 6 for ¹77Lu and 3 for ?°Y.

Absorbed dose from alpha emitters demonstrated a lower radiation penetration in the trabecular bone (over a factor of 100) compared to beta emitters suggesting that toxic effects on bone marrow would be less when these isotopes are conjugated to agents that stay within the blood pool. Future work will help to define the maximum absorbed dose for alpha TRT of tumors, compatible with the tolerance of bone marrow.


Not Applicable / None Entered.


Not Applicable / None Entered.

Contact Email