Title : Nuclear and radio chemistry perspective: Development of FDM 3D-printed tissue-equivalent radiological phantom and alanine chemical dosimetry for radiotherapy
Abstract:
In recent decades, the incidence and fatality rate of cancer have been at a high level worldwide. With the development of therapeutic technology and equipment, radiotherapy has become one of the important means for the control and treatment of cancer due to its high cure rate. The accuracy of tumor target dose in radiotherapy is directly related to the effect of radiotherapy and the occurrence of accidental medical irradiation. In order to improve the cure rate of radiotherapy and avoid accidental medical exposure, strict quality assurance needs to be implemented during radiotherapy. According to the need for precise control of absorbed dose in the quality assurance of radiotherapy, a new tissue equivalent radiological anthropomorphic phantom was developed using Fused deposition modeling (FDM) 3D printing technology, and the anatomical information of that was derived from the CT image of the human body. The exterior outline and the structure of the internal organs were designed to simulate the real human body. Different organs and tissues were made from different materials which are tissue equivalent to themselves in X-rays and gamma rays. After developed, the effective atomic number and electron density per unit mass of the phantom materials were calculated. The density, element composition ratio and mass attenuation coefficient were verified by experiments. The mass attenuation coefficient was obtained based on Monte Carlo simulation. And the above parameters were compared with the standard values. The results show that the materials are tissue equivalent well. Different from the traditional water phantom, the radiological anthropomorphic phantom is mainly used to study the energy deposition distribution of radiotherapy X-ray and γ-ray in human tissues and organs. Alanine chemical dosimeters can be placed in the phantom for dose measurement. Alanine is an amino acid. When irradiated by ionizing radiation (such as X-rays, γ-rays, etc.), its molecular structure undergoes stable free radical changes. This change has a clear quantitative relationship with the absorbed radiation dose. The signal intensity of free radicals can be detected by electron paramagnetic resonance (EPR) technology, and then the radiation dose absorbed by alanine can be inferred. The study of energy deposition and distribution of different radiations in organs and tissues of human body by using the radiological anthropomorphic phantom. This work provides an important research basis for radiotherapy quality assurance technology and helps to accurately control the absorbed dose of target organs in radiotherapy, and provides a basis and reference for the formulation and implementation of radiotherapy plan.
