Selective internal radiotherapy using proton-induced monochromatic X-rays and cancer-targeting nanoparticle sensitizers

In this paper, we propose a highly-selective radiotherapy based on monochromatic X-rays and cancer-targeting gold nanoparticle (GNP) sensitizer. In order to deliver the low-energy monochromatic X-rays which selectively ionize the Au L-shell into the cancerous tissue deep inside the patient’s body, we employ a syringe-needle type X-ray source driven by an MeV proton beam. From a simple numerical evaluation, we found that optimization of the primary X-ray energy was essential to enhance the dose around the nanoparticle. In order to confirm the above idea qualitatively, we performed a simulation experiment in the atmosphere, where 100 nm Au foils were used instead of the GNPs. The experimental result showed that the dose around the Au foils was much higher than that at positions away from the foils, owing to short-range secondary electrons from the foils.