In silico dosimetry of low-dose rate brachytherapy using radioactive nanoparticles

PURPOSE Nanoparticles (NPs) with radioactive atoms incorporated within the structure of the NP or bound to its surface, functionalized with biomolecules are reported as an alternative to low-dose-rate seed-based brachytherapy. In this study, authors report a mathematical dosimetric study on low-dose rate brachytherapy using radioactive NPs. METHOD Single-cell dosimetry was performed by calculating cellular S-values for spherical cell model using Au-198, Pd-103 and Sm-153 NPs. The cell survival and tumour volume vs time curves were calculated and compared to the experimental studies on radiotherapeutic efficiency of radioactive NPs published in the literature. Finally, the radiotherapeutic efficiency of Au-198, Pd-103 and Sm-153 NPs was tested for variable: administered radioactivity, tumour volume and tumour cell type. RESULT At the cellular level Sm-153 presented the highest S-value, followed by Pd-103 and Au-198. The calculated cell survival and tumour volume curves match very well with the published experimental results. It was found that Au-198 and Sm-153can effectively treat highly aggressive, large tumour volumes with low radioactivity. CONCLUSION The accurate knowledge of uptake rate, washout rate of NPs, radio-sensitivity and tumour repopulation rate is important for the calculation of cell survival curves. The self-absorption of emitted radiation and dose enhancement due to AuNPsmust be considered in the calculations. Selection of radionuclide for radioactive NP must consider size of tumour, repopulation rate and radiosensitivity of tumour cells.Au-198 NPs functionalized with Mangiferin are a suitable choice for treating large, radioresistant and rapidly growing tumours.