基于多层硅像素芯片的质子断层辐射成像研究OA

To address the range uncertainty in proton therapy arising from the conversion of hounsfield units(HU)to relative stopping power(RSP)in conventional X-ray CT,this study proposes and constructs a high-resolution proton computed tomography(pCT)detection system based on multi-layer silicon pixel detectors.By using the Geant4 Monte Carlo platform,the tomographic imaging process of a 230 MeV clinical proton pencil beam was simulated with a radial scanning step of 0.1 mm.Performance evaluations regarding RSP accuracy and image quality were conducted using the Catphan 600 series phantom.The results indicate that the system exhibits excellent linear response characteristics in measuring the RSP of 7 materials in CTP404 module with varying densities(R2=0.999 72).Through linear calibration,RSP reconstruction deviations for various tissue-equivalent materials—including bone-equivalent material(RSP≈1.84)—were maintained within 1%.In validation tests using a human tissue-equivalent phantom(customized CTP515 module),the system successfully distinguished between muscle and lens tissues with a density difference of only～2%,demonstrating superior low-contrast resolution.Analysis of the high-resolution line-pair module(CTP528)revealed that,under the straight-line path assumption,multiple Coulomb scattering(MCS)effects induced an attenuation of approximately 38.4%in high-frequency signal amplitude,resulting in a modulation transfer function(MTF)of 10%at approximately 5 lp/cm.This study not only validates the technical feasibility of the multi-layer pixel detector architecture for achieving sub-millimeter,iso-source image-guided proton therapy,but also establishes a high-precision RSP quantification workflow that provides core algorithmic support and a viable solution for further reducing range uncertainty in proton therapy.