Which radiation type has the highest linear energy transfer (LET)?

Which radiation type has the highest linear energy transfer (LET)?

• A. Beta
• B. Gamma
• C. Alpha
• D. Ultraviolet

Answer: (C)

LET, or linear energy transfer, is the energy a radiation particle deposits per unit length as it travels through matter. High LET means energy is dumped very densely into a small region, causing more localized and often more severe damage. Alpha particles are heavy, doubly charged helium nuclei, so their electric field creates a dense cluster of ionizations over a short track in tissue, giving them a much higher LET than the lighter beta particles or the photons such as gamma rays and ultraviolet light. Because photons interact more sparsely and deposit energy along longer paths, their LET is much lower.

LET, or linear energy transfer, is the energy a radiation particle deposits per unit length as it travels through matter. High LET means energy is dumped very densely into a small region, causing more localized and often more severe damage. Alpha particles are heavy, doubly charged helium nuclei, so their electric field creates a dense cluster of ionizations over a short track in tissue, giving them a much higher LET than the lighter beta particles or the photons such as gamma rays and ultraviolet light. Because photons interact more sparsely and deposit energy along longer paths, their LET is much lower.