DNA Dosimeter Measurement of Relative Biological Effectiveness for 160 kVp and 6 MV X Rays

Area of Science:

• Radiation Biology
• Biophysics
• Medical Physics

Background:

• Assessing the biological impact of different radiation qualities is crucial in radiotherapy and radiation protection.
• Existing methods for measuring DNA damage and biological effectiveness can be complex and time-consuming.

Purpose of the Study:

• To develop and validate a DNA dosimeter for detecting DNA double-strand breaks (DSBs).
• To evaluate if the DNA dosimeter can accurately reflect the relative biological effectiveness (RBE) of low-energy (160 kVp) versus high-energy (6 MV) X-rays.

Main Methods:

• A DNA dosimeter was constructed using 4-kb DNA strands on magnetic beads, labeled with fluorescein to detect DSBs.
• DNA dosimeters, cell lines (mNs-5, HT-22, Daoy), and comet assays were exposed to calibrated 160 kVp and 6 MV X-rays.
• Relative biological effectiveness (RBEDSB, RBEcell survival, RBEcomet assay) was calculated by comparing responses at equivalent doses.

Main Results:

• The DNA dosimeter demonstrated RBE values for 160 kVp X-rays that were in agreement with cell survival and comet assay results.
• Measured RBE values for the DNA dosimeter at 9 Gy were 1.21 ± 0.24.
• Comet assay RBE at 3 Gy was 1.32 ± 0.16, showing consistency with the DNA dosimeter.

Conclusions:

• The developed DNA dosimeter effectively measures changes in radiobiological effects caused by different X-ray energies.
• This DNA dosimeter shows potential as a reliable tool for assessing radiation quality and biological effectiveness.
• The findings support the use of this dosimeter for quantifying DNA damage and RBE in radiobiology research.