Biological Effectiveness of Accelerated Protons for Chromosome Exchanges.

Area of Science:

• Radiation biology
• Human cell research
• Genetics

Background:

• Understanding the biological effects of proton radiation is crucial for radiation protection and therapy.
• Chromosome aberrations are key indicators of radiation-induced DNA damage.

Purpose of the Study:

• To investigate chromosome exchanges induced by protons of varying energies (5-2500 MeV) in human lymphocytes.
• To determine the relative biological effectiveness (RBE) of these proton beams.
• To assess the impact of shielding on proton-induced DNA damage.

Main Methods:

• Human lymphocytes were irradiated in vitro with seven proton energies.
• Chromosome damage was analyzed using three-color fluorescence in situ hybridization (FISH) chromosome painting.
• Relative biological effectiveness (RBE) was calculated relative to gamma rays.

Main Results:

• All proton energies induced a higher percentage of complex-type chromosome exchanges than acute gamma rays.
• The linear dose-response term for chromosome exchanges was consistent across proton energies.
• Shielding showed minor differences, with lower RBE values for shielded compared to unshielded high-energy proton beams.

Conclusions:

• Proton radiation, particularly at higher energies, induces significant complex chromosome exchanges.
• Findings have implications for optimizing radiation protection in space and refining proton therapy techniques.
• The balance between linear energy transfer (LET) and secondary particle production influences biological response.