| Exposure (X) |
Coulomb/kg (C/kg), roentgen (R) |
The amount of charge liberated per unit mass of air |
| Absorbed dose (D) |
Gray (Gy), radiation absorbed dose (rad) |
The amount of energy absorbed per unit mass of the absorbing medium |
| Equivalent dose (HT) |
Sievert (Sv), roentgen equivalent man (rem) |
The absorbed dose equivalent, accounting for the type of radiation: absorbed dose multiplied by a radiation weighting factor (WR), accounting for differences in biologic effect per unit of absorbed dose. For photons and electrons, WR is 1 |
| Effective dose (HE) |
Sievert (Sv), roentgen equivalent man (rem) |
A calculated quantity used to express and compare risk, where WT is the assigned tissue weighting factor representing the relative radiation sensitivity of that tissue. Current WT values can be found in ICRP3 Report 103 |
| Air kerma |
Gray (Gy) |
The kinetic energy released in air; at photon energies used for diagnostic imaging, this quantity is very close to the absorbed dose in air |
| Air kerma at the interventional reference plane (Ka,r) |
Gray (Gy) |
The air kerma determined at the interventional reference plane, generally defined as 15 cm toward the X-ray tube from the isocenter of the fluoroscope c-arm gantry. This is the quantity displayed on most modern fluoroscopes |
| Peak skin dose (Dskin,max) |
Gray (Gy) |
The highest absorbed dose to the skin |
