Comparison of estimated human effective dose of 67Ga- and 99mTc-labeled bombesin based on distribution data in mice

Internal absorbed dose calculation in body organs due to injection of Rhenium-188 labeled to Mu-9 antibody

The use of radiopharmaceuticals has gained a special place in the diagnosis and treatment of cancers and evaluation of the function of different organs of the body. In this study, the absorbed dose distribution of organs after injection of 188Re-Mu-9 has been investigated using MIRD method and MCNP-4C simulation code. The 188Re-Mu-9 labeled was injected the mouse body and the amount of 188Re-labeled accumulation was evaluated after 1, 4 and 2 4 h. Having a map of the distribution of radiopharmaceutical activity in the animal body, it is possible to convert it into a human model to obtain the internal dose received by 188Re-Mu-9 injection using the MIRD calculation method and the MCNP simulation code. According to the results of the study, the animal/human model can be acceptable method for dose estimation of antibody-based radiopharmaceuticals.

Human Dose Assessment of 68Ga-NODAGA-RGD-BBN Heterodimer Peptide based on Animal Data

Aims

Calculation of the absorbed dose in human organs is one of the first steps for developing new radiopharmaceuticals. The aim of this study is to estimate the human absorbed dose of a newly developed 68Ga-NODAGA-RGD-BBN radiolabeled compound.

Materials and Methods

68Ga-NODAGA-RGD-BBN was prepared by varying different parameters at optimized conditions. The stability of the radiolabeled peptide in phosphate-buffered saline (PBS) and in human serum was evaluated for 120 min. Afterward, the biodistribution of the complex was assessed in normal and tumor-bearing mice, at least for 120 min postinjection. Finally, the human absorbed dose of 68Ga-NODAGA-RGD-BBN was estimated based on mice data using Radiation Dose Assessment Resource and Spark method.

Results

68Ga-NODAGA-RGD-BBN was produced with radiochemical purity of more than 98% (high-performance liquid chromatography/ radio thin layer chromatography (RTLC)) with high stability in PBS buffer and in human serum at least for 2 h. The complex demonstrated high uptake in gastrin-releasing peptide receptor-expressing tumors compared to other nontarget organs. Furthermore, the dose assessment for the complex showed that the kidneys receive the highest absorbed dose in comparison with other organs.

Conclusion

The result of this study showed that 68Ga-NODAGA-RGD-BBN is an effective and radiolabeled ligand for tumor detection, however more studies are still needed.

Internal dosimetry studies of 177Lu-BBN-GABA-DOTA, as a cancer therapy agent, in human tissues based on animal data

The goal of using radiopharmaceuticals for therapeutic purposes is twofold: first, the most damage to cancer cells and, second, the most negligible dose transfers to healthy tissues. As ¹⁷⁷Lu has the potential to cure a wide range of malignancies due to its varied range of beta energies, ¹⁷⁷Lu-BBN-GABA-DOTA has been developed for therapeutic applications. In addition, ¹⁷⁷Lu-BBN-GABA-DOTA can be over-expressed on gastrin-releasing peptide (GRP) receptors of the prostate, breast, small cell lung cancer, gastric, and colon tumors. The purpose of this study was to calculate the amount of dose absorption in human body organs using medical internal radiation dose (MIRD) and GATE code methods, after animal injection. In this study, the amount of absorbed dose in different organs (spleen, kidney, Lung, Pancreas, Heart, Adrenal, Intestine, Stomach, and Liver) were calculated for 1-MBq accumulation of ¹⁷⁷Lu-BBN-GABA-DOTA in source organs (spleen, kidney, Lung, Pancreas, Heart, Adrenal, Intestine, Stomach, and Liver) using Monte Carlo Simulation (GATE code) with Zubal phantom. Moreover, compared with MIRD method, the results of the simulation showed considerable consistency. It was estimated that a 1-MBq administration of ¹⁷⁷Lu-BBN-GABA-DOTA to the human body would result in an absorbed dose of 1.07E-02 mGy and 4.97E-02 (MIRD method) and 1.26E-02 mGy and 5.19E-02 (Gate code) in the Pancreas and adrenal 120 h after injection, respectively. The highest and lowest percentage differences between MIRD and Gate results are related to the Pancreas and spleen, respectively. Finally, the results showed that there is a good agreement between MIRD method and Gate code simulation for absorbed dose estimation.

Internal dosimetry studies of 170Tm-EDTMP complex, as a bone pain palliation agent, in human tissues based on animal data

Radiopharmaceuticals with therapeutic applications are designed to deliver high doses of radiation to target organs with minimizing unwanted radiation to healthy tissues. Owing to the potential of targeted radiotherapy to treat a wide range of malignancies, ¹⁷⁰Tm -EDTMP was developed for possible therapeutic applications. This study describes absorbed dose prediction of ¹⁷⁰Tm-EDTMP in human organs after animal injection which is determined via medical internal radiation dose (MIRD) and MCNP-4C code methods. It was estimated that a 1-MBq administration of ¹⁷⁰Tm-EDTMP into the human body would result in an absorbed dose of 37.9 mGy (MIRD method) and 38.02 mGy (MCNP-4C code) in the bone surface after 60 days post injection. Highest and lowest difference between MIRD and MCNP results are for lung and bone surface respectively. Finally, the results show that there is a good agreement between MIRD method and MCNP-4C simulation code for absorbed dose estimation.