Which statement reflects LET comparison between alpha and gamma radiation?

• A. Alpha radiation has higher LET than gamma radiation
• B. Gamma radiation has higher LET than alpha radiation
• C. Beta radiation has higher LET than gamma radiation
• D. Neutrons have higher LET than alpha radiation

Answer: (A)

LET, or linear energy transfer, is the energy deposited per unit length as radiation travels through matter. Alpha particles are heavy and carry a +2 charge, so they interact strongly with atoms and create a dense cluster of ionizations over a very short path. In tissue, this means a large amount of energy is deposited in a tiny volume along a short track. Gamma rays are photons with no charge and interact much less frequently, spreading their energy over longer distances with much sparser ionization. Because of this, alpha radiation deposits energy at a much higher rate per unit length than gamma radiation. So the statement that alpha radiation has higher LET than gamma radiation is correct.