What is the quality factor for alpha (ray) particles?

The quality factor for alpha particles is 20. This factor is a crucial component in radiation protection as it quantifies the biological impact of different types of radiation based on their ability to cause damage to living tissue.

Alpha particles are heavy, positively charged particles that are relatively large compared to other types of radiation, such as beta particles or gamma rays. Due to their mass and charge, when alpha particles interact with matter, they have a high linear energy transfer (LET), meaning they can deliver a significant amount of energy over a short distance. This high energy deposition capability can lead to substantial biological effects, particularly when alpha-emitting materials are ingested or inhaled, as they can cause serious cellular and tissue damage at the atomic level.

The quality factor is used to convert the absorbed dose of radiation (measured in grays) into an equivalent dose (measured in sieverts), which reflects the biological effects of the radiation. For alpha particles, the high quality factor reflects their significant potential for damaging tissue, hence why it is set at 20. This makes them far more biologically impactful on a per unit dose basis than lower LET radiation types, highlighting the importance of appropriate safety measures when handling materials that emit alpha particles.