Which statement best describes the potential for biological harm per unit energy among radiation types?

Which statement best describes the potential for biological harm per unit energy among radiation types?

• A. 1 megavolt of alpha particles
• B. 1 megavolt of gamma rays
• C. 1 megavolt of x-rays
• D. 1 megavolt of beta particles

Answer: (A)

High linear energy transfer (LET) is what makes a given amount of energy more biologically damaging. Alpha particles have the highest LET among common radiation types, so they deposit energy very densely over a short distance in tissue. That dense ionization causes complex, clustered DNA damage that is harder for cells to repair, leading to greater biological harm per unit energy than beta particles or photons. Gamma rays and X-rays are low-LET photons that spread energy more sparsely, while beta particles have intermediate LET but still less harm per unit energy than alpha. So, for the same energy, alpha radiation carries the greatest potential for biological harm.

High linear energy transfer (LET) is what makes a given amount of energy more biologically damaging. Alpha particles have the highest LET among common radiation types, so they deposit energy very densely over a short distance in tissue. That dense ionization causes complex, clustered DNA damage that is harder for cells to repair, leading to greater biological harm per unit energy than beta particles or photons. Gamma rays and X-rays are low-LET photons that spread energy more sparsely, while beta particles have intermediate LET but still less harm per unit energy than alpha. So, for the same energy, alpha radiation carries the greatest potential for biological harm.