Microscopic evaluation of nanoparticle dose enhancement by inverse Compton scattering source using Monte Carlo simulation

Abstract

Radiotherapy with nanoparticles has been widely investigated, showing an energy dependence performance. A Compact radiotherapy facility providing energy-tuneable X-rays is highly demanded. Inverse Compton Scattering (ICS) sources can offer quasi-monochromatic and continuous energy-tuneable X-rays, enabling optimization of radiation enhancement effect for various nanomaterials. This study simulated enhanced radiotherapy with an ICS source using the Geant4 at microscale. The radiation enhancement effect of a typical nanomaterial, i.e., gold nanoparticles (GNPs), was evaluated and compared with the conventional X-ray tube. An improved model of tumors was built to evaluate the microscopic dose enhancement factor (DEF) of different nanoparticles, including GNPs and hafnium oxide nanoparticles. DEF of nanoparticles showed an energy dependence and the largest DEF of GNPs was 17.89 at 36 keV with monochromatic beams. The ICS source displayed a similar performance in terms of DEF (17.77 at 38 keV), which was higher than the 80 kV X-ray tube (12.80), due to the narrow bandwidth. The improved simulation method showed that the DEF was 22.8 for GNPs at 30 keV and 9.5 for hafnium oxide nanoparticles at 25 keV. The implementation of the ICS source, with a higher DEF at optimal energy, is feasible for enhanced radiotherapy. The continuous energy-tuneable property makes it a promising equipment for the application of enhanced radiotherapy with different nanomaterials.