What does the term "linear energy transfer" refer to?

Linear energy transfer (LET) is a crucial concept in radiation physics that quantifies how much energy is deposited by radiation as it travels through a medium. The term specifically refers to the rate at which energy is transferred to the material per unit length of the radiation's path, or track length, through the absorber.

This means that when charged particles, such as alpha or beta particles, pass through a biological tissue or other materials, they deposit energy continuously along their path. The higher the LET, the more energy is deposited in a given distance, which is particularly important in understanding how different types of radiation interact with biological tissues. High LET radiation tends to cause more significant biological damage because it produces more ionizations and excitations within the tissue, making it particularly relevant in fields like radiation therapy and radiobiology.

Other options describe different aspects of interactions with radiation but do not capture the essence of what linear energy transfer specifically refers to—energy deposition per unit distance. For example, while the total energy absorbed by a tissue or the total number of ionizations created pertains to overall effects or outcomes, they do not directly describe the rate of energy deposition, which is the core of the LET concept. Additionally, while efficiency in energy transfer in radiation therapy is related