Room: AAPM ePoster Library
Purpose: To construct and optimize a DNA-based detector for quantifying DNA single strand and double strand breaks (SSBs and DSBs, respectively) due to ionizing radiation.
Methods: We constructed phantoms from polycarbonate with cylindrical cavities ranging from 2 to 5 mm diameter and 1 to 4 mm depths. The range of cavity sizes were used to test the ease of pipetting commercial plasmid DNA, pBR322 (Thermo Fisher Scientific), into the cavities for subsequent exposure to ionizing radiation and for removal from the cavities for analysis. Cavities sizes were also tested for their ability to retain 3 ul of DNA solution without a seal at three phantom orientations (upright, upside-down, and sideways) with surface tension for times ranging from one hour to one day. Different materials (e.g., Parafilm and wax-paper) and designs (e.g., air-gap between the cavity surface and overlying seal) were tested for their ability to seal the cavities and prevent spillage of the DNA sample during transport. The DNA-based detector was irradiated to 20 and 30 Gy and agarose gel electrophoresis was used to analyze the DNA damage.
Results: The optimal cavity dimensions with minimum depth to contain the DNA without a seal were found to be 2 mm in diameter and depth. Parafilm and Wax-paper combination with a 1 mm air gap between it and the DNA solution in the cavity provided the optimal seal design. Irradiation of the detector showed that it can be transported and used in the clinic and later analyzed to assess DNA SSB and DSB damage.
Conclusion: We have constructed and optimized the design of a DNA-based detector for quantifying DNA damage. This detector would be useful in clinical radiotherapy applications (e.g., heavy charged particle beams and/or FLASH therapy) that would benefit from assessing DNA damage due to both radiation dose and radiobiological effects.