What are the common units for dose rate and dose, and how are they related mathematically?

• A. Dose rate: Gy/h; Dose: Gy; Dose = Dose rate × exposure time.
• B. Dose rate: Sv/h (or Gy/h); Dose: Sv (or Gy); Dose = Dose rate × exposure time.
• C. Dose rate: rem/h; Dose: Gy; Dose = Dose rate × time.
• D. Dose rate: Sv/h; Dose: Gy; Dose = Dose rate / time.

Answer: (B)

Dose rate tells you how much dose accumulates each hour, while dose is the total amount accumulated. In radiation protection, the absorbed dose is measured in gray (Gy) and the biologically weighted dose in sievert (Sv). The rate can be expressed as Gy/h or Sv/h, and the total dose is found by multiplying that rate by the exposure time, D = (dose rate) × (time), assuming the rate is constant. If the rate varies, you’d integrate it over the exposure time.

For example, 0.5 Gy/h for 4 hours yields 2 Gy; 0.4 Sv/h for 5 hours yields 2 Sv. The same relationship holds if you use Sv/h with Sv or Gy/h with Gy—the units stay consistent and you multiply by time to get the total dose. Other options mix incompatible units or imply dividing by time, which doesn’t produce the total dose.