What is the primary characteristic of radiation that determines the depth of tissue response?

The primary characteristic of radiation that determines the depth of tissue response is the energy or quality of radiation. This is crucial because higher energy radiation, such as gamma rays and x-rays, can penetrate deeper into tissues compared to lower energy radiation. The quality, or energy level, affects how much energy is deposited in the tissue and how far the radiation can travel before being absorbed or scattered.

For example, low-energy radiation tends to be absorbed quickly and does not penetrate deeply into biological tissues, which limits its impact. In contrast, high-energy radiation can pass through tissue layers, leading to a greater likelihood of ionization events occurring at varying depths within the tissue. This relationship highlights why understanding the energy of radiation is essential for assessing potential risks and managing exposure effectively in both diagnostic and therapeutic contexts.