How does an increase in linear energy transfer (LET) affect biological damage?

An increase in linear energy transfer (LET) is linked to a rise in biological damage due to the nature of how energy is deposited in biological tissues. LET refers to the amount of energy that a radiation particle transfers to the material it traverses per unit distance. Higher LET radiation, such as alpha particles or heavy ions, transfers energy more densely along its path. This higher density of energy deposition can lead to more significant damage to cellular structures, including DNA, because the radiation causes more ionizations and excitations in a concentrated area.

As a result, tissues exposed to high LET radiation are at greater risk of cellular injury, which can manifest as mutations, cancer, and other health issues. In contrast, low LET radiation, such as gamma rays and X-rays, typically results in less concentrated energy deposition and consequently less biological damage, highlighting the direct relationship between increased LET and heightened biological effects. Recognizing this relationship is vital in fields such as radiation therapy, where the goal is to maximize damage to cancer cells while minimizing harm to surrounding healthy tissue.