How do you convert absorbed dose to dose equivalent for different radiation types?

• A. H = D × Q, where Q is the radiation-type quality factor (gamma/beta ~1, alpha ~20).
• B. H = D / Q
• C. H = D × energy
• D. H = D × safety factor 2

Answer: (A)

The key idea is converting absorbed dose into a risk-adjusted value by accounting for how damaging different radiation types actually are. Absorbed dose D tells you how much energy is deposited in tissue, but not all energy depositions have the same biological effect. The dose equivalent H adjusts D with a quality factor Q that represents how biologically effective the radiation is. Multiply D by Q to get H. Since gamma and beta radiation have Q around 1 and alpha radiation has a much higher Q (about 20), the same energy deposition from alpha particles poses a far greater biological risk, and this is reflected in a higher dose equivalent. So the correct relation is H = D × Q.

Dividing by Q would underestimate risk for high-LET radiations; multiplying by energy or applying a generic fixed factor isn’t how dose equivalent is defined.