Irradiating Single Cells with Single Ions A Feasibility Study

Abstract: Background: To gain more knowledge of the mechanism behind the appearance of radiation induced cancer, the cellular response at low doses has to be studied. A Single Ion Hit Facility (SIHF) at the Lund Nuclear Microprobe Laboratory will be used for this purpose. The facility allows single MeV ions to hit single living cells.Purpose: The goals of this work were to i) design a suitable cell dish where the cells are attached during irradiation and investigate how the cells tolerate being ii) exposed to air, iii) placed in a vertically position and if it is possible to iv) determine the lineal energy and the specific energy both theoretically and experimentally.Results: It was shown that the specially designed cell dish, made of 200 nm thick Si3N4 glued on acrylic plastic fulfilled its purpose to fit in the irradiation chamber without any reconstructions of the sample holder had to be done, and it could easily be improved i.e. include more Si3N4 irradiation windows. This thesis shows that there is a linear relationship between time of air exposure and survival and consequently the time of exposure of air has to be considered when studying the cell response after irradiation. The lineal energy and the specific energy in cells were determined theoretically to be 13.9±2.7 keVμm−1 and 82±16mGy respectively. From irradiation two energy spectra were obtained, with and without cells. No significant difference were found between the spectra and therefore, no lineal energy or specificenergy could be calculated.Conclusion: To minimize cell damage other than from irradiation, the cells cannot be handled in open air. It was shown that cells positioned vertically move, which cannot be allowed when aiming at sub micrometer structures. A cell dish with five 200 nm thick Si3N4 windows, was constructed. V79 hamster cells were cultured on the dish before irradiation, from which two energy spectra were obtained, with and without cells. These two spectra were analyzed and the result could neither prove or discard the theoretical results due to no statistical significance.