Room: Exhibit Hall | Forum 1
Purpose: Targeted alpha particle therapy (TAT) agents used in internal radiotherapy show heterogeneous distributions in organs. This observation suggests that there are different toxicity risks to different organ structures following the administration of TAT. Using an alpha camera, the activity distribution can be acquired in organs of animal models in ex-vivo tissue sections. We have investigated the spatial distribution of our recently published TAT compound in rat kidneys and calculated the dose using Monte Carlo (MC) simulations in order to estimate the relative radiation toxicity risk for different regions of kidney.
Methods: We have investigated the distribution of 4 derivatives of our TAT in the kidneys of Sprague-Dawley rats (n=16). Animals were divided into four groups. Each animal was intravenously injected with 4 ÂµCi of activity. For each subject, animals were humanely euthanized and kidneys removed at 24 h post-injection, imaged in coronal plane using an alpha camera, and whole kidney activity was counted. MC simulations were performed using MCNP6.2. The kidney model represents two regions of the kidney: the cortex and the medulla. Absorbed dose was calculated from the energy deposition tally.
Results: The TAT spatial distribution in kidney was acquired for all 4 compounds and it was observed that the agents were primarily retained in the kidney cortex. The MC simulations showed that the absorbed dose to cortex was higher than that calculated for the whole organ using the standard methodology.
Conclusion: Since the standard method of averaging the radiation dose to the entire organ mass underestimated the actual dose being absorbed in the region of the cortex, our results demonstrate that greater detail is required to determine the regional dosing within organ sites. To accomplish this, high structural resolution data of rat kidney will be needed to serve as a voxelized model for MC simulations.
Not Applicable / None Entered.