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A syringe needle-type proton-induced monochromatic X-ray source was proposed to solve the issue that could occur in practical brachytherapy, such as loss of seed sources and radiation exposure to surgical staff. This paper discusses comparison between experimental results and a Monte Carlo numerical simulation of the dose distribution around the needle. Some simulation results for different source designs are presented as a first step of the design optimization.

In this paper, we have proposed monochromatic X-ray microbeams, produced by a proton-induced X-ray technique and a polycapillary X-ray half lens, as a tool for micro-X-ray fluorescence (XRF) analysis. A 30 μm thick planar Cu target was irradiated by a 2.5 MeV proton beam to produce Cu Kα X-rays (8.0 keV), and a polycapillary X-ray half lens was utilized to focus the X-rays emitted behind the Cu target. The focal spot size of the focused X-ray beam was 250 μm at full width at half maximum, which was verified using a knife-edge scanning method. The output focal distance and the depth of focus of the optics were measured to be 47 mm and 1 mm, respectively. A square grid pattern of Co thin films, formed on a thick Cu substrate by thermal evaporation, was used as a test sample for evaluation of the analytical performance of the micro-XRF setup. Two-dimensional mapping of the Co distribution on the Cu substrate was successful, and the spatial resolution was consistent with the beam spot size. For this Co layer, a minimum detection limit of 2.3 ng was achieved.

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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.