Absorbed Dose (SQA National 5 Physics): Revision Note

Absorbed dose

• Ionising radiation carries energy that can be transferred to matter when absorbed, potentially resulting in damage to biological tissues

• The absorbed dose is defined as:

The amount of energy absorbed during radiation exposure per unit mass of tissue

• The absorbed dose can be calculated using the following relationship:

$D=\frac{E}{m}$

• Where:

  • $D$ = absorbed dose, measured in grays (Gy)

    • $1\mathrm{Gy}=1\mathrm{J}{\mathrm{kg}}^{-1}$

  • $E$ = energy, measured in joules (J)

  • $m$ = mass of tissue, measured in kilograms (kg)

• Absorbed dose is a measure of the amount of energy deposited in the exposed tissue

• It does not reflect the varying biological impacts of different radiation types on the body

  • The same absorbed dose from different kinds of radiation can cause different levels of biological damage

• The potential biological harm from radiation exposure depends on:

  • the absorbed dose

  • the type of radiation

  • the specific organs or tissues affected

• People who work with radiation, such as medical imaging or nuclear power, wear dosimeter badges to measure their absorbed dose over time

A dosimeter badge