Exposure to which type of radiation produces the least ionization in biological tissues?

Gamma radiation produces the least ionization in biological tissues compared to alpha, beta, and X-ray radiation. This is primarily due to its high penetration ability and low mass. Gamma rays are electromagnetic waves and interact with matter differently from charged particles.

When gamma radiation passes through biological tissues, it has a lower likelihood of interacting with atoms to cause ionization, which is the process that leads to cellular damage. In contrast, alpha particles, being heavy and positively charged, have a high probability of ionizing atoms in their immediate vicinity, leading to more significant biological effects. Beta particles, which are electrons or positrons, also have a relatively higher ionization potential than gamma rays because they are charged, allowing them to interact more readily with biological tissues.

X-rays strike a balance between penetration and ionization capacity; they cause ionization but are not as damaging as alpha particles. Therefore, among the four types, gamma radiation is responsible for the least ionization within biological tissues, making it the correct answer.