Current progress of the biological single-ion microbeam at FUDAN |
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Authors: | X F Wang J Q Li J Z Wang J X Zhang A Liu Z J He W Zhang B Zhang C L Shao L Q Shi |
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Institution: | (1) Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai, China;(2) Key Laboratory of Applied Ion Beam Physics (Fudan University), Ministry of Education of People’s Republic of China, No. 220. Handan Road, 200433 Yangpu District, Shanghai, China;(3) Institute of Radiation Medicine, Fudan University, No. 2094, Xietu Road, 200032 Xuhui District, Shanghai, China |
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Abstract: | A biological microbeam for precisely positioned single-ion/single cell irradiation is built in the Institute of Modern Physics
in Fudan University, Shanghai, China, based on the tandem accelerator (2 × 3MV) in the laboratory. In this paper, the developing
progress of the FUDAN microbeam is reported, including the newly constructed beam line, the microbeam collimator, the ion
detection system, and the cell-imaging and targeting systems. Statistical models are proposed for evaluating the spatial resolution
and dosage precision of the microbeam. By taking the collimated ions as a Gaussian beam, the spatial resolution can be evaluated
by the full width at half maximum of the 2-D Gaussian distribution, which is determined by fitting the proportions of peripheral
pits outside specific radii in the pit clusters etched on ion track detectors to a 2-D Gaussian distribution. In the preset
hitting of defined ion number, by taking the real delivered number of ions as an independent identically distributed random
variable (iidrv), according to the Law of Large Numbers and Central Limit Theorem, the expected value μ and standard deviation
σ of the real delivered ion number in a preset N-ion hitting can be determined by approaching the normal distribution of N (μ, σ
2/n) with the proportions of the mean counts of pits in multiple pit clusters on ion track detectors. By the values of μ, σ and additional assumptions, statistical dosage precision evaluations can be made on the preset hitting. From the linear fit
curve of μ(N) and the power function fit curve of σ(N) on different preset ion numbers, characteristic factors k, b, A, p can be extracted for a precision evaluation independent of the specific preset ion number. |
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