Hi'CT: a pixel sensor-based device for ion tomography

• Published in: Nuclear science and techniques Vol. 34; no. 7; pp. 61 - 71
• Main Authors: Chen, Yi-Lun, Wang, Hong-Kai, Zhang, Shi-Yu, Yang, Hai-Bo, Zhao, Cheng-Xin
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.07.2023; School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100049,China; Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China; Advanced Energy Science and Technology Guangdong Laboratory,Huizhou 516003,China%Department of Radiation Oncology,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing 100021,China
• Subjects: Beam Physics; Nuclear Energy; Particle Acceleration and Detection; Particle and Nuclear Physics; Physics; Physics and Astronomy; Image-guided; Tracking; Computed tomography; Monte Carlo; Phantoms; Heavy-ion imaging; Radiotherapy; Silicon pixel detectors
• ISSN: 1001-8042; 2210-3147
• DOI: 10.1007/s41365-023-01251-x

Carbon ions, commonly referred to as particle therapy, have become increasingly popular in the last decade. Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion radiotherapy. Range uncertainty is currently the largest contributor to dose uncertainty in normal tissues, leading to the use of safety margins in treatment planning. One potential method is the direct relative stopping measurement (RSP) with ions. Heavy-ion CT (Hi′CT), a compact segmented full digital tomography detector using monolithic active pixel sensors, was designed and evaluated using a 430 MeV/u high-energy carbon ion pencil beam in Geant4. The precise position of the individual carbon ion track can be recorded and reconstructed using a 30 μm × 30 μm small pixel pitch size. Two types of customized image reconstruction algorithms were developed, and their performances were evaluated using three different modules of CATPHAN 600-series phantoms. The RSP measurement accuracy of the tracking algorithm for different types of materials in the CTP404 module was less than 1%. In terms of spatial resolution, the tracking algorithm could achieve a 20% modulation transfer function normalization value of CTP528 imaging results at 5 lp/cm, which is significantly better than that of the fast imaging algorithm (3 lp/cm). The density resolution obtained using the tracking algorithm of the customized CTP515 was approximately 10.5%. In conclusion, a compact digital Hi'CT system was designed, and its nominal performance was evaluated in a simulation. The RSP resolution and image quality provide potential feasibility for scanning most parts of an adult body or pediatric patient, particularly for head and neck tumor treatment.