Radiosensitisation Effects Of Gold Nanoparticles Evaluation Using Cell Survival Curve Models For Radiotherapy
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Date
2016-04
Authors
Ab Rashid, Raizulnasuha
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Introduction: Gold nanoparticles (AuNPs) have been experimentally proven to induce the radiosensitisation effects in radiation therapy. Generation of copius secondary electron and high LET Auger electron due to the increase in photoelectric interaction cross section promotes escalation on the biological damage that significantly reduces the cell survival. Cell survival described by radiobiological models could be used to predict the detrimental response of cells to radiation due to the presence of AuNPs. In this study, the linear quadratic (LQ), multi-target (MT) and repairable conditionally-repairable damage (RCR) cell survival curve models were used to describe the cell survival with and without AuNPs. The applicability of these models to give accurate description on the radiosensitisation effects by AuNPs to cell survival was investigated.
Methods: HeLa cells were irradiated using photon and electron beams including HDR Brachytherapy source at different doses. Standard clonogenic assay were used to determine the cell survival. The experimental data were then fitted to the LQ, MT and RCR model using OriginPro 9.2 software. Sensitisation enhancement ratio (SER) were calculated from the fitting curves generated from these models. Results and Discussion: Fitting curve of the LQ, MT and RCR models for cell survival with and without AuNPs were found to be close to the experimental data.
Sensitisation effect proven in all the curves fitted, those showed the steep initial slope and small shoulder for irradiation with AuNPs. The MT model was found to be the best agreement with the experimental cell survival especially for the cell survival with high doses range, with SER calculated from LQ, MT and RCR curves showed value range from 1.05% - 2.8%. All the predictions of sensitisation and enhancement occurred were visualized by the parameters from the models used. LQ model showed a larger α and α/β ratio, while for MT model showed a smaller n, D1, D0 and Dq and the RCR model depicted the enhancement and cell damage occurred by higher values of a, b and c. The parameterisation of LQ, MT and RCR showed correlation with the SER which indicate the applicability of these models to predict the effects of radiosensitisation by AuNPs. Conclusion: The results showed that the radiosensitisation effects are highly dependent on beams energy and on the concentration of AuNPs, as showed the enhancement up to 3 fold. The low energy range is the most suitable for maximum dose enhancement. However megavoltage photon and electron beams also produce a slightly effective radiosensitisation. The LQ, MT and RCR models proven the capability for describing the biological response of the radiosensitisation effects accordingly to the doses range applied. LQ and RCR models able to evaluate the effect of radiosensitization at the early low dose given, range from 0 Gy to 4 Gy, while MT model able to evaluate at high doses range from 5 Gy to 10 Gy.
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Keywords
Gold nanoparticles , radiosensitisation effects in radiation therapy.