DANB Radiation Health and Safety (RHS) Practice Exam

The process that directly causes DNA damage when exposed to ionizing radiation is direct ionization. This occurs when the high-energy photons or particles from ionizing radiation interact directly with the molecules in the DNA, resulting in the removal of tightly bound electrons. This ionization can lead to the formation of free radicals and other reactive species, which can then cause breaks in the DNA strands or alter the molecular structure of the nucleotides.

Direct ionization is significant because it can lead to various types of DNA damage, including single-strand breaks, double-strand breaks, or lesions that can affect the integrity of the genetic material. Understanding this process is crucial for assessing the biological effects of radiation exposure and the associated risks of potential mutations or cancer development.

In contrast, while other processes like indirect ionization and radiation absorption also have roles in radiation interactions, they do not involve a direct impact on DNA molecules. Indirect ionization typically refers to interactions that involve secondary particles created by radiation, leading to biological effects through intermediary processes, rather than through a direct hit on the DNA itself.