Optimizing dose enhancement with Ta 2 O 5 nanoparticles for synchrotron microbeam activated radiation therapy

Abstract

Microbeam Radiation Therapy (MRT) exploits tumour selectivity and normal tissue sparing with spatially fractionated kilovoltage X-ray microbeams through the dose volume effect. Experimental measurements with Ta 2 O 5 nanoparticles (NPs) in 9L gliosarcoma treated with MRT at the Australian Synchrotron, increased the treatment efficiency. Ta 2 O 5 NPs were observed to form shells around cell nuclei which may be the reason for their efficiency in MRT. In this article, our experimental observation of NP shell formation is the basis of a Geant4 radiation transport study to characterise dose enhancement by Ta 2 O 5 NPs in MRT. Our study showed that NP shells enhance the physical dose depending microbeam energy and their location relative to a single microbeam. For monochromatic microbeam energies below ∼70 keV, NP shells show highly localised dose enhancement due to the short range of associated secondary electrons. Low microbeam energies indicate better targeted treatment by allowing higher microbeam doses to be administered to tumours and better exploit the spatial fractionation related selectivity observed with MRT. For microbeam energies above ∼100 keV, NP shells extend the physical dose enhancement due to longer-range secondary electrons. Again, with NPs selectively internalised, the local effectiveness of MRT is expected to increase in the tumour. Dose enhancement produced by the shell aggregate varied more significantly in the cell population, depending on its location, when compared to a homogeneous NP distribution. These combined simulation and experimental data provide first evidence for optimising MRT through the incorporation of newly observed Ta 2 O 5 NP distributions within 9L cancer cells. Disciplines Engineering | Science and Technology Studies Publication DetailsEngels, E., Corde, S., McKinnon, S., Incerti, S., Konstantinov, K., Rozenfeld, A., Tehei, M., . Optimizing dose enhancement with Ta2O5 nanoparticles for synchrotron microbeam activated radiation therapy. Physica Medica: an international journal devoted to the applications of physics to medicine and biology, 32 (12)

Investigation of track structure and condensed history physics models for applications in radiation dosimetry on a micro and nano scale in Geant4

“…The results of this research have significant impact on studies which intend to investigate the physics mechanism at the basis of the radiobiological effects of radiation at cellular and sub-cellular level in radiotherapeutic applications (Incerti et al 2016), such as the investigation of dose enhancement produced by high-Z nanoparticles (e.g. (Sakata et al 2016, Douglass et al 2013, Engels et al 2016, McKinnon et al 2016a, McKinnon et al 2016b), the characterisation of radio-emitters for Targeted Particle Therapy (e.g. (Huang et al 2012)), the study of the effect of radiation in cellular targets other than the nucleus (e.g.…”

Radiosensitizing high-Z metal nanoparticles for enhanced radiotherapy of glioblastoma multiforme

“…10 b, c) [ 117 ]. The same group also reported the dose enhancement effect of the NPs under a synchrotron beam with the energy range of 50–150 keV in 9L gliosarcoma cells [ 118 ].

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Microbeam radiation therapy — grid therapy and beyond: a clinical perspective

“… 60 Dose enhancement was looked at in relation to MRT, especially with nanoparticles. 61 , 62 Advice was produced for the optimal energy spectrum to be used in any clinical trials of MRT. 26 , 63 …”