DNA strand break induction of aqueous plasmid DNA exposed to 30 MeV protons at ultra-high dose rate.

Radiation cancer therapy with ultra-high dose rate exposure, so called FLASH radiotherapy, appears to reduce normal tissue damage without compromising tumor response. The aim of this study was to clarify whether FLASH exposure of proton beam would be effective in reducing the DNA strand break induction. We applied a simple model system, pBR322 plasmid DNA in aqueous 1 × TE solution, where DNA single strand breaks (SSBs) and double strand breaks (DSBs) can be precisely quantified by gel electrophoresis.

Cell lines of the same anatomic site and histologic type show large variability in intrinsic radiosensitivity and relative biological effectiveness to protons and carbon ions.

Purpose: To show that intrinsic radiosensitivity varies greatly for protons and carbon (C) ions in addition to photons, and that DNA repair capacity remains important in governing this variability.

Methods: We measured or obtained from the literature clonogenic survival data for a number of human cancer cell lines exposed to photons, protons (9.9 keV/μm), and C-ions (13.

Cytoplasmic Radiation Induced Radio-Adaptive Response in Human Lung Fibroblast WI-38 Cells.

It has been reported that in cells exposed to low-dose radiation, radio-adaptive responses can be induced which make irradiated cells refractory to subsequent high-dose irradiation. However, whether adaptive responses are possible when only the cytoplasm, not the nucleus, of the cell is exposed to radiation is still unclear. In this study, using the proton microbeam facility at the National Institute of Radiological Sciences (Japan), we found that cytoplasmic irradiation activates radio-adaptive responses in normal human lung fibroblast WI-38 cells.