Assessment of Radiation Burden on Organs and Tissues from the Aptamer-Based Radiopharmaceutical for PET/CT Imaging of Lung Cancer

Aptamers acting as the basis for radiopharmaceutical drugs based on carbon-11 have proven themselves to be highly sensitive and specific agents for imaging tumors and metastases. However, the lack of knowledge about the patterns of their metabolism in the body and the radiation exposure on organs significantly hinders their clinical use. To fill this gap, a study of the biodistribution of a radiopharmaceutical based on the carbon-11 radiolabeled aptamer LC-18, as well as an assessment of the radiation exposure on organs and tissues in vivo were carried out. Purpose: To evaluate the doses of radiation to organs, tissues and the whole body during intravenous administration of a radiopharmaceutical based on the carbon-11 radiolabeled LC-18 aptamer to obtain information on the safety of its further application in PET/CT diagnostics Material and methods: 11CH3-LC-18 complex was obtained in the laboratory of the Center for Nuclear Medicine of the FSRCC FMBA of Russia. Absorbed and effective doses of the drug accumulated in organs and tissues of mice were determined radiometrically. To calculate absorbed doses in organs and tissues data on the biodistribution of the 11CH3-LC-18 complex in mice were extrapolated to a model of the human body. Results: According to the calculations it was found that the highest absorbed doses after administration of 200 MBq of a radiopharmaceutical were noted in the small intestine (3.67 ± 0.40 mGy), kidneys (2.68 ± 0.32 mGy), liver (2.00 ± 0.16 mGy), spleen (1.42 ± 0.17 mGy) and on the walls of the stomach (1.35 ± 0.14 mGy). The lowest accumulation was observed in the skin (0.48 ± 0.05 mGy), brain (0.51 ± 0.06 mGy) and thyroid gland (0.58 ± 0.06 mGy). The extrapolated absorbed doses do not exceed the thresholds noted by the UNSCEAR and ICRP. Conclusion: The calculated predictive values of the absorbed doses in organs and tissues allow us to draw a conclusion about the safety of the studied radiopharmaceutical based on the carbon-11 labeled aptamer LC-18.