Potential application of slice heavy ion beam radiography by energy difference method for future theranostic of carbon ions therapy

Carbon ions therapy has become a globally prevalent treatment due to its highly efficiency in tumor eradication by including DNA double-strand breaks within the Bragg peak region, while avoiding the need for invasive surgery. A pre-treatment assessment using X-ray technology is necessary to draw the tumor morphology for carbon ions impinging. However, metal implants adjacent to tumor area often generate heavy artifacts during CT scans, compromising accurate tumor evaluation. We propose a radiography method utilizing high-energy carbon ion beams, which exhibit stronger penetration and density sensitivity compared to X-ray. In this study, we investigate the important physical properties of marginal range (where Bragg peaks location) radiography by using high energy carbon ions beams incidence different morphology targets at the Heavy Ion Research Facility in Lanzhou (HIRFL). By modulating the beam energy, the detailed interior structures of targets are visualized slice-by-layer. The results demonstrated that the marked copper plate and the CPU targets achieved density resolution of about 1.6 % at 10.9 g/cm² and spatial resolution of 500 $\mu$ m. For the ball-point pen, the sequence radiographs of different depth features are presented. An agreement is found between the Geant4 simulation and the experimental results. Both low-Z and high-Z material components in the ball-point pen are distinctly differentiated, and a three-dimensional visual target is reconstructed. Through in vitro experiment, we validate the important physical properties of marginal range radiography and extending its application to tumor cases with high Z metal implants. The excellent resolution power is expected to solve the tumor morphology caused by metal artifacts in CIRT treatment. Such combination of marginal range radiography with Bragg peak cancer therapy provides a unique solution for the future development of carbon ion theranostic.