Estimation of Human-Absorbed Dose of 99mTc-MAA, Using MIRD Method Based on Animal Data and Comparison with MCNP Simulation Code

99mTc-Macro Aggregated-Albumin (99mTc-MAA) has been evaluated as a useful perfusion study agent. In this study, the human absorbed dose of 99mTc-MAA was estimated with MIRD and MCNP methods based on animal biodistribution data and finally compared with ICRP publication data.

In this study, for investigating the biodistribution of 99mTc-MAA, after radiolabeling of MAA with Technetium-99m, it was injected to mice via the tail vein. After 1-120 min post injection, the mice were sacrificed and some of their tissues dissected and counted for calculating the percentage of the injected dose per gram (% ID/g) and the absorbed dose. Then, the obtained data was converted to equivalent data in human for each tissue.

Dose prediction shows that the highest absorbed dose is observed in the lungs (MIRD: 6.8E-2 mGy/MBq, MCNP: 6.32E-2 mGy/MBq). There is good agreement between the results obtained from MIRD and MCNP simulation for lungs.

According to the present results and comparison with ICRP publication data, animal dissection model and simulation MCNP code can be useful tools for internally-absorbed dose estimation of pulmonary radiopharmaceuticals.